Elecraft K3S User Manual

ELECRAFT

®

K3S

HIGH-PERFORMANCE

160 – 6 METER TRANSCEIVER

OWNER’S MANUAL

Revision A1, May 26, 2015

Copyright © 2015, Elecraft, Inc.

All Rights Reserved

2

Contents

A Note to K3S Owners .................................... 3!

Key to Symbols and Text Styles ...................... 3!

Quick-Start Guide ............................................ 4!

Introduction ...................................................... 7!

K3S Features ........................................................7!

Specifications ......................................................8!

Customer Service and Support ..........................10!

Front Panel ..................................................... 11!

Control Groups ..................................................11!

Display (LCD) ...................................................12!

LEDs ..................................................................13!

Front Panel Connectors .....................................13!

Primary Controls ...............................................13!

Multi-Function Controls ....................................14!

VFO Tuning Controls ........................................14!

Keypad ...............................................................15!

Memory Controls ...............................................16!

Message Record/Play Controls ..........................16!

RIT and XIT Controls .......................................16!

Rear Panel ...................................................... 17!

Connector Groups ..............................................17!

Control and Audio Connections ........................18!

Basic Operation ............................................. 23!

Receiver Setup ...................................................25!

Reducing Interference and Noise ......................27!

Transmitter Setup ..............................................28!

Voice Modes (SSB, AM, FM) ...........................30!

CW Mode ..........................................................32!

Data Modes ........................................................33!

Advanced Operating Features ........................ 35!

Text Decode And Display .................................35!

CW-to-DATA ....................................................36!

Tuning Aids: CWT and SPOT ..........................36!

Audio Effects (AFX) .........................................37!

APF and Dual-Passband CW Filtering ..............37!

Receive Audio Equalization (EQ) .....................37!

Transmit Audio Equalization (EQ) ...................37!

SPLIT and Cross-Mode Operation ....................38!

Extended Single Sideband (ESSB) ....................38!

General-Coverage Receive ................................38!

VFO B Alternate Displays .................................38!

Alarm and Auto Power-On ................................38!

Using the Sub Receiver .....................................39!

Receive Antenna In/Out ................................... 41!

Buffered I.F. Output for Panadapters ............... 41!

Using the 100-550 kHz Range .......................... 41!

Using Transverters ............................................ 41!

Scanning ........................................................... 42!

Main and Sub Receiver Antenna Routing ..... 43!

Preamp 2 Limitations ........................................ 45!

Remote Control of the K3S ............................ 46!

Options and Accessories ................................ 47!

Firmware Upgrades ........................................ 47!

Configuration ................................................. 48!

Crystal Filter Setup ........................................... 48!

Module Enables ................................................ 49!

Miscellaneous Setup ......................................... 50!

VFO A Knob Friction Adjustment ................... 50!

VFO B Knob Friction Adjustment ................... 51!

Real Time Clock Battery Replacement ............ 51!

Calibration Procedures ................................... 52!

Synthesizer ........................................................ 52!

Wattmeter ......................................................... 52!

Transmitter Gain ............................................... 52!

Reference Oscillator ......................................... 53!

Front Panel Temperature Sensor ...................... 54!

PA Temperature Sensor .................................... 54!

S-Meter and RF GAIN Control ........................ 54!

Menu Functions ............................................. 55!

MAIN Menu ..................................................... 55!

CONFIG Menu ................................................. 57!

Troubleshooting ............................................. 69!

Parameter Initialization ..................................... 72!

Module Troubleshooting .................................. 73!

Theory Of Operation ...................................... 77!

RF BOARD ...................................................... 77!

KAT3A (ATU) and KANT3 ............................ 79!

KIO3B (Audio/Digital I/O) .............................. 79!

Front Panel and DSP ......................................... 79!

KREF3 (Ref./2nd LO) ........................................ 81!

KSYN3A (Synthesizer) .................................... 81!

Firmware ........................................................... 81!

K3S Block Diagram .......................................... 83!

Appendix A: Crystal Filter Installation .......... 84!

Index .............................................................. 88!

3

A Note to K3S Owners

On behalf of our entire design team, we’d like to thank you for choosing the Elecraft K3S transceiver.

The K3S is the same size and weight (~9 lbs.) as its predecessor, the K3. Yet nearly all internal modules have
been redesigned, providing enhanced performance and many new features. These include:

• Ultra low-noise synthesizer for exceptional receiver dynamic range and transmit signal purity

• USB port for convenient, single-cable computer control and digital audio interface (an RS232 port is

provided, as well, for station compatibility and P3 interfacing); pg. 18

• Built-in second preamp for weak-signal work on 12, 10, and 6 meters; pg. 25

• Three attenuator settings (5/10/15 dB) to optimize performance in strong-signal conditions; pg. 25

• Improved audio circuitry for clean, low-distortion stereo speaker output; pg. 80

• Low-loss ATU option with a true bypass relay, maximizing efficiency with every antenna

• Accurate high-speed CW transmit timing, even when using SPLIT, RIT, and XIT

• 100-550 kHz coverage, including low-level 630-meter (472 kHz) transmit; pg. 41

Exterior changes include all-stainless-steel hardware, new display bezel, and a soft-touch VFO tuning knob.

With its unique combination of compact size and world-class performance, your new K3S can handle the most
demanding operating situations, whether you’re at home or halfway around the world.

73,

Wayne, N6KR
Eric, WA6HHQ

Key to Symbols and Text Styles

Important – read carefully

Operating tip

LSB

. .

LCD icon or characters

LED

Enter keypad function

XMIT

TUNE

Tap switch function (labeled on a switch)

Hold switch function (labeled below a switch; hold for 1/2 sec. to activate)

SQL

PWR

MON

Rotary control without integral switch

Tap switch function of rotary control (labeled above a knob)

Hold switch function of rotary control (labeled below a knob; hold for 1/2 sec.)

MAIN:VOX GN

Typical MAIN menu entry

CONFIG:KAT3

Typical CONFIG menu entry

4

Quick-Start Guide

To get started using your K3S right away, please read this page and the two that follow, trying each of the
controls. The text uses braces to refer to numbered elements in the front- and rear-panel illustrations below. For
example, {1} in the text refers to . Later sections provide greater detail on all aspects of K3S operation.

The first thing you need to know about the K3S is that most switches have two functions. Tap (press

briefly) to activate the function labeled on a switch. Hold for about ½ to 1 second to activate the function

labeled below the switch. In the text, tap functions are shown like this example: MENU . An example of a hold
function is CONFIG . Additional typographical conventions are shown on the previous page.

Try tapping MENU {8}. This brings up the MAIN menu. Rotating VFO B {19} selects menu entries, while
rotating VFO A {22} changes their parameters. Tap MENU again to exit the menu.

1

5

Connections

• Connect a power supply to the DC input jack {26} (see Specifications, pg. 8).

• On the K3S /100, a circuit breaker is provided on the fan panel for the 100-W stage {39}.

• You can power an accessory device from the switched DC output jack {40} (1.0 A max).

• Connect antenna to ANT1 {29} and ground {38}. With an ATU (pg. 24), you can also use

ANT2 {28}. AUX RF {27} is for the sub RX; see pg. 17. ANT3 {30} is used with the
internal 2-m module (K144XV). Connect an RX-only antenna to RX ANT IN {35}.

The Basics

• Press POWER {5} to turn on the K3S. If there are any error indications, refer to pg. 74.

• TAP and HOLD Functions: Tapping briefly activates the function labeled on a switch.

Holding for about 1/2 second activates the function labeled below a switch.

• Tap either end of BAND {7} to select a band, and MODE {6} for the mode. Set AF gain

using AF {2}. Set RF to max. Plug phones in at {3}. For SUB controls, see pg. 39.

• The large knob {22} controls VFO A (upper display, {10}). The medium knob {19}

controls VFO B (lower display, {11}). VFO A is main RX/TX except in SPLIT (pg. 38).

• CMP / PWR is one of four multifunction controls {24}. Each has two primary

functions, indicated by green LEDs. The knob has a built-in switch; tap it to select either

CMP (compression level) or PWR (power output). Hold the knob in to access its

secondary function, MONitor level. Tap again to restore the primary function.

Filter Controls

• Rotate the SHIFT / LO CUT and HI CUT / WIDTH controls {23} to adjust the filter

passband. Crystal filters FL1-FL5 are automatically selected as you change the band-
width. Tap either knob to select shift/width or hi cut/lo cut. (See filter info, pg. 85.)

• Hold SHIFT / LO CUT to NORMalize the bandwidth (e.g., 400 Hz CW, 2.8 kHz SSB).

• Hold HI CUT / WIDTH to alternate between two filter setups, I and II (per-mode).

• Tap X FIL {13} to select crystal filters manually; this also removes any passband shift.

Voice Modes

{1}

• Hold METER {8} to see CMP / ALC levels. While talking, set MIC {25} for 4-7 bars

of ALC, and CMP for the desired compression. Then return to SWR / PWR (pg. 30).

• Optional: Hold TEST {6} for TX TEST mode; allows off-air TX adjustments (pg. 13).

• Hold CMP / PWR {24} to set speech MONitor level; tap to return to CMP / PWR.

• Hold VOX {7} to select PTT or VOX. Hold SPEED / MIC to set VOX DELAY.

• Details: VOX, pg. 31; TX EQ, pg. 37; MIC SEL, pg. 55; SSB/AM/FM, pg. 30.

CW Mode

{37}

• SPEED {25} sets the CW keyer speed. Hold this knob to set semi-break-in DELAY.

Hold QSK {7} to select full QSK (pg. 32.). Hold VOX {7} to select hit-the-key CW.

• Hold PITCH {18} to set sidetone pitch. Hold CMP / PWR to set sidetone MON level.

• Tap CWT {18} for tuning aid {9} (pg. 36). With CWT on, SPOT auto-spots (pg. 32).

• To select CW text decode/display mode, hold TEXT DEC {18}; rotate VFO B (pg. 32).

• CW keying is converted to DATA in FSK D and PSK D modes (below and pg. 36).

• Hold APF {13} to turn on audio peaking (APF) or dual-passband filtering (pg. 32).

Data Modes

{33}

• Tap MODE {6} until you see the DATA icon turn on (see Data Modes, pg. 33).

• Hold DATA MD {18}. Use VFO B to select from: DATA A (PSK31, JT65, and other

soundcard-based modes), AFSK A (soundcard-based RTTY), FSK D (RTTY via data
input or keyer), or PSK D (PSK via data input or keyer). VFO A selects data baud rate
for internal encoder/decoder, if applicable. APF turns on an RTTY filter (DTF, pg. 34).

• Hold PITCH {18} to select mark tone and shift (for encoder/decoder and RTTY filter).

• Hold TEXT DEC {18} to set up text decode. CWT shows tuning aid (pg. 36).

6

VFOs
and RIT/XIT

• RATE {21} selects 10 or 50 Hz VFO/RIT tuning. See VFO menu entries, pg. 57.

• FINE {21} selects 1-Hz steps. COARSE selects large steps (MAIN menu, VFO CRS).

• Tap FREQ ENT {21} to enter frequency in MHz using numeric keypad & decimal point.

Tap return ( ) to complete the entry, or tap FREQ ENT again to cancel (pg. 15).

• Hold SCAN to start/stop scanning. SCAN must be preceded by a memory recall (pg. 42).

• The RIT and XIT offset knob {17} has LEDs that show -/0/+ offset (pg.16). Tap CLR

{16} to zero the offset. Hold CLR for > 2 sec. to add the offset to VFO A, then zero it.

Transmit,
ATU, and
Antenna
Controls

• The TX LED {4} indicates that the K3S is in transmit mode. The ∆ f LED turns on if the

RX and TX frequencies are unequal, e.g. SPLIT, RIT/XIT, cross-mode (pg. 13).

• XMIT {8} is equivalent to PTT {36}. TUNE puts out full CW power in any mode.

• ATU TUNE {8} initiates antenna matching (pg. 24). ATU enables or bypasses the ATU.

• ANT selects ANT1 or ANT2. RX ANT selects main or RX antenna (KXV3B module).

Preamp and
Attenuator

• Tap PRE {13} to turn on the preamp (pg. 25). On 12-6 m, preamp 2 can be used.

• Hold ATT {13} to turn on the attenuator (pg. 25). Hold ATT for 2 seconds to go into the

MAIN:ATTEN menu entry; per-band attenuation level can be set to 5/10/15 dB.

NB, NR,
and Notch

• Tap NB {12} to enable DSP and I.F. noise blanking. Hold LEVEL to set DSP NB level

(VFO A) and I.F. NB level (VFO B). Fully CCW is OFF in both cases. (Pg. 27.)

• Tap NR {12} to turn on noise reduction (saved per-mode). Hold ADJ to tailor noise

reduction for the present band conditions (pg. 27).

• NTCH {12} turns on auto-notch in SSB mode, manual notch in others. MAN turns on

manual notch in any mode, and is also used to adjust manual notch frequency (pg. 27).

SPLIT,
BSET,
and SUB

• Hold SPLIT {13} to enter split mode (RX on VFO A, TX on VFO B). If VFOs A and B

are on different frequencies in SPLIT mode, the Delta-F LED (∆ f ) will turn on (pg. 13).

• Hold BSET {13} to adjust VFO B / sub RX settings independently of VFO A (pg. 39).

• Tap SUB {20} to turn on the sub receiver (pg. 39). VFO B controls its frequency.

• Hold DIV {20} to engage diversity mode (pg. 40), which can reduce signal fading.

• VFO B can be linked (slaved) to VFO A using CONFIG:VFO LNK menu entry.

Memories,
Messages, and
DVR

• To store a frequency memory, tap V M {14}, then: tap M1-M4 {15} to save a per-band

quick memory; or tap 0 -9 to save a general-purpose quick memory; or rotate VFO A to
select from memories 0-99, then tap V M again to save. Tap M V to recall. (Pg. 16.)

• REC and M1-M4 {15} are also used to record & play voice/CW/DATA messages. The

KDVR3 option is required for voice messages and AF REC / AF PLAY (pg. 31).

Menus and
Switch Macros

• MENU & CONFIG {8} access the MAIN and CONFIG menus. VFO B selects entries;

VFO A changes parameters. In general, CONFIG menu entries are used less often.

• Tapping DISP {8} within menus shows information about each entry on VFO B (pg. 55).

• Menu entries can be assigned to programmable switches PF1 , PF2 {16} and M1-M4 {15}

(pg. 55). These switches can also be used to create custom SPLITs, etc. (macros, pg. 23).

Other
Features

• RX and TX EQ (MAIN menu) provide 8 bands of receive/transmit equalization (pg. 37).

• Tap AFX {18} to enable the selected audio effect (see CONFIG:AFX MD, pg. 55).

• Tap DISP {8} and use VFO B to show time, supply voltage, etc. on VFO B (pg. 38).

• The ALARM function (MAIN:ALARM menu entry) can be used to remind you about a

contest, net, or QSO schedule, and can even turn the K3S on at alarm time (pg. 38).

• The KIO3B module provides a rich set of AF {34} and digital {31-33} I/O (pg. 17).

7

Introduction

This comprehensive manual covers all the features
and capabilities of the Elecraft K3S transceiver. We
recommend that you begin with the Quick-Start
Guide (pg. 4). The Front Panel section (pg. 11)
and Rear Panel section (pg. 17) are for general
reference. Basic Operation (pg. 23) and Advanced
Operation (pg. 35) fill in the details.

Anytime you add new filters or options, refer to

Configuration (pg. 48) for setup instructions.

K3S Features

The K3S offers a number of advanced features to
enhance performance and versatility:

Receiver

• Up to five crystal roofing filters with

bandwidths as narrow as 200 Hz (pg. 25)

• Optional high-performance sub receiver,

also with up to five crystal filters, allows
true diversity receive (pg. 39)

• Second preamp for weak-signal work on

12-6 meters (pg. 25)

• Three attenuation settings (pg. 25)

• Narrow ham-band front-end filters, plus

wider band-pass filters for general-coverage
receive with KBPF3A option (pg. 47);
KPF3A also provides good sensitivity
down to 100 kHz, including 2200-m and
630-m bands (pg. 41)

DSP

• 32-bit I.F. DSP for advanced signal

processing, including full stereo and other
binaural effects (pg. 37)

• Passband tuning and programmable

DSP/crystal filter presets (pg. 14)

• 8-band transmit and receive EQ (graphic

equalization) (pg. 37)

• Versatile digital voice recorder (DVR)

option (pg. 31)

CW and Digital Modes

• Built-in digital-mode demodulation with

text displayed on the LCD (CW, RTTY,
PSK31/PSK63) (pg. 35)

• APF (audio peaking filter) for digging out

weak signals in CW mode (pg. 32)

• Internal CW-to-RTTY or CW-to-

PSK31/PSK63 encoding for casual digital­mode QSOs without a computer (pg. 36)

• CW decoded and displayed as you send –

great for improving CW skills (pg. 35)

• Automatic CW/data signal spotting and

manual fine-tuning display (pg. 32)

User Interface

• Dual VFOs with independent modes,

bands, and filter settings (pg. 14)

• 100 memories with alphanumeric labels,

plus 4 quick-memories per band (pg. 16)

• Dedicated message play controls for use in

CW, data, and voice modes (pg. 32)

• Real-time clock/calendar with alarm and

automatic power-on (pg. 38)

• Utility displays show voltage, current drain,

RIT/XIT offset, front panel temperature,
PA heat sink temperature, etc. (pg. 38)

• Built-in menu help text (pg. 23)

• Programmable switch “macros” to

automate often-used operations (pg. 46)

• Custom “power-on banner” can be

displayed on power-up (set up using the K3

Utility program)

Connectivity

• Remote control via USB or RS232 (pg. 46)

• Line-level analog audio jacks, plus digital

audio via the USB port (pg. 17)

• Firmware upgrades via the Internet (pg. 47)

• Front and rear mic and headphone jacks

• Full stereo audio with two speaker outputs

Options and Accessories (pg. 47)

• ATU, sub receiver, digital voice recorder,

100-W PA, 2-meter module, external
reference lock, and other internal options

• Fully integrated P3 Panadapter, 500+ W

KPA500 amplifier and KAT500 automatic
antenna tuner, K3/0-Mini remote control
panel, and other accessories

8

Specifications

Some specifications apply only if the corresponding option modules are installed (see Options, pg. 47).

GENERAL

Frequency Range

Main and Sub Receivers: 100 kHz - 30 MHz and 44-54 MHz (see receiver Sensitivity
spec). Transmitter: Amateur bands between 1.8 and 54 MHz (limits vary by country).
144-148 MHz with K144XV option. 630 m (472 kHz) at ~0.5 mW) with KBPF3A.

Expanded coverage of MARS allocations on request (U.S.).

Tuning Step Sizes

1, 10, 20, and 50 Hz fine steps; user-configurable coarse tuning steps (per-mode).
Direct keypad frequency entry in either MHz or kHz.

Frequency Memories

100 general-purpose memories; 4 scratch-pad memories per band.

Frequency Stability

+/- 5 ppm (0-50 C) TCXO standard; +/- 1 ppm TCXO opt. (+/- 0.5 PPM typ., 0-50 C).
K3EXREF option locks TCXO to an external 10-MHz reference (+/- 1 to 2 Hz typ.).

Antenna Jacks

50 ohms nominal. One SO-239 supplied (2nd ant. jack supplied with KAT3A ATU).
BNC jacks for RX antenna in/out and transverter in/out (on supplied KXV3B module).

Modes

USB, LSB, AM, FM, CW, DATA (FSK D [direct], AFSK A [Audio], PSK D [Direct]
and DATA A [Audio]). Built in PSK, RTTY, and CW text decode/display.

VFOs

Dual VFOs (A and B) with separate weighted tuning knobs

Remote Control Port

USB-B port and RS232 port (RJ45 jack plus supplied RJ45 to DE9 adapter). USB port
can also provide line-level audio in/out on the same cable.

Audio I/O

Line-level isolated TX/RX audio interface (mono in, stereo out); front (1/4”) and rear
(1/8”) stereo headphone jacks; stereo speaker jack.

Transverter Interface

Transmit, 0 dBm typ.; XVTR IN/OUT connectors (BNC) on supplied KXV3B
module. KXV3B also includes connectors for K144XV internal 2-meter module.

Buffered IF output

BNC connector (KXV3B); see pg. 41 for interface recommendations.

Other I/O

Key/Keyer/Computer, Paddle, PTT In, and KEY Out. Band information output via
binary interface and AUXBUS on ACC connector.

Real-Time Clock/Calendar

Accuracy: Approx. +/- 20 ppm (+/- 2 seconds/day). U.S. and E.U. date formats.
Battery: 3 V coin cell (see pg. 51 for replacement instructions).

Supply Voltage
and Current

13.8 V nominal (11 V min, 15 V max). 17-22 A typical in TX for K3S/100, 3-4 A
typical in TX for K3S/10. 1.0 A typical RX (less sub receiver). When using reduced
supply voltage (< 12 V), power output should be reduced (e.g. 70 W at 11 V).
Recommended supply: 13.8VDC @ 25A, continuous duty for K3S/100; 13.8VDC @
6A for K3S/10. For best results, use the supplied 5 foot (1.53 m) power cable. When a
battery is used, both sides of the battery cable should be protected by fast-blow fuses.

Accessory DC output

Switched, 1.0 A max; 13 V no-load, 12 V max load (@ Vsupply = 13.8 V)

Weight (K3S/100)

Approx. 8.5 lbs. (3.8 kg). With KRX3A sub receiver option, 9.5 lbs. (4.3 kg).

Size

Enclosure only, 4.0 x 10.7 x 10.0 in., HWD (10.2 x 27.2 x 25.4 cm). With projections,

4.4 x 11.1 x 11.8 in. (11.2 x 28.2 x 30.0 cm).

9

RECEIVER (Main and Sub)*

Sensitivity (MDS)

(Typical values, in
500 Hz bandwidth)

HF, Preamp off: -133 dBm. Preamp 1: -138 dBm. Preamp 2 (12/10/6 m): -145 dBm.

Reduced sensitivity near 8.2 MHz (first I.F.) and from 44-49 MHz. Sensitivity
decreases gradually below 1.8 MHz due to intentional high-pass response at the T-R
switch. (Use RX ANT input, XVTR IN, or sub receiver’s AUX input to avoid the
high-pass filter loss.) Note: KBPF3A option required for full general coverage
(including 100 to 1700 kHz). Sensitivity falls off below 200 kHz; MDS typically

-115 dBm at 137 kHz (2200 m band) using RX ANT IN or XVTR IN.

Dynamic Range

IMD3 at 5 and 20 kHz spacing, 500 Hz BW: ~100 dB. Blocking: ~140 dB.

Image and I.F. Rejection

> 70 dB

Audio Output

2.5 W per channel into 4 ohms; typ. 10% THD @ 1 kHz, 2 W

S-Meter

Nom. S9 = 50 µV, preamp 1 on; user-adjustable

Preamp

Preamp 1 (all bands): 10 dB; preamp 2 (12/10/6 meters): 20 dB

Attenuator

Main receiver: 5/10/15 dB levels, settable per-band. Sub receiver, 10 dB.

Noise Blanker

Adjustable, multi-threshold/multi-width hardware blanker plus DSP blanker

Receive AF graphic EQ

+/- 16 dB/octave, 8 bands

Filter Controls

IF Shift/Width & Lo/High Cut with automatic crystal filter selection

* Receive specifications are guaranteed only within ham bands. Dynamic range measurements based on 400-Hz, 8-pole
filter. See www.elecraft.com for full list of available crystal filters.

TRANSMITTER *

Output Power

K3S/100: 0.1 W –100 W typ. Suggested max from 51-52 MHz, 85 W; 52-54, 70 W.
K3S/10 (or K3S/100 with PA bypassed): 0.1 W –12 W, HF-10 m; 8 W max on 6 m.
XVTR OUT: HF, -10 to +1.8 dBm; at 472 kHz (630 m), -3 dBm (see pg. 41).
K144XV: ~10 W, 144-148 MHz.

Note: K3S/100 output can be set up to 110 W. However, IMD and spurious products
are specified at 100 W, the recommended maximum (lower on 6 m; see above).

Duty Cycle

CW and SSB modes, 100% 10-min. 100W key-down at 25 C ambient

True RF Speech Processor

Adjustable compression

Transmit AF graphic EQ

+/- 16 dB/octave, 8 bands

SSB TX Bandwidth

4 kHz max (> 2.8 kHz requires 6 kHz or 13 kHz crystal filter)

VOX

DSP-controlled, adjustable threshold, delay, and anti-VOX

Full and Semi CW Break-In

Adjustable delay; diode T/R Switching

SSB Carrier Suppression

> 50 dB

Harmonic / Spurious Outputs

> 50 dB below carrier @ 100W (> 60 dB on 6 meters)

CW Offset/Sidetone

300-800 Hz, adjustable (filter center frequency tracks sidetone pitch)

Mic Connector

Front panel, 8 pin; rear panel 3.5 mm; switchable DC bias

* Transmit specifications are guaranteed only within ham bands.

10

Customer Service and Support

Technical Assistance

You can send e-mail to [e-mail] and we will respond quickly – typically the same day
Monday through Friday. If you need replacement parts, send an e-mail to [e-mail]. Telephone
assistance is available from 9 A.M. to 5 P.M. Pacific time (weekdays only) at 831-763-4211. Please use e-mail
rather than calling when possible since this gives us a written record of the details of your problem and allows us
to handle a larger number of requests each day.

Repair / Alignment Service

If necessary, you may return your Elecraft product to us for repair or alignment. (Note: We offer unlimited email
and phone support, so please try that route first as we can usually help you find the problem quickly.)

IMPORTANT: You must contact Elecraft before mailing your product to obtain authorization for the
return, what address to ship it to and current information on repair fees and turn around times. (Frequently we
can determine the cause of your problem and save you the trouble of shipping it back to us.) Our repair location
is different from our factory location in Aptos. We will give you the address to ship your kit to at the time of
repair authorization. Packages shipped to Aptos without authorization will incur an additional shipping charge

for reshipment from Aptos to our repair depot.

Elecraft 1-Year Limited Warranty

This warranty is effective as of the date of first consumer purchase (or if shipped from the factory, the date the
product is shipped to the customer). It covers both our kits and fully assembled products. For kits, before requesting
warranty service, you should fully complete the assembly, carefully following all instructions in the manual.

Who is covered: This warranty covers the original owner of the Elecraft product as disclosed to Elecraft at the time
of order. Elecraft products transferred by the purchaser to a third party, either by sale, gift, or other method, who is
not disclosed to Elecraft at the time of original order, are not covered by this warranty. If the Elecraft product is being
bought indirectly for a third party, the third party’s name and address must be provided at time of order to ensure
warranty coverage.

What is covered: During the first year after date of purchase, Elecraft will replace defective or missing parts free of
charge (post-paid). We will also correct any malfunction to kits or assembled units caused by defective parts and
materials. Purchaser pays inbound shipping to us for warranty repair; we pay shipping to return the repaired
equipment to you by UPS ground service or equivalent to the continental USA and Canada. For Alaska, Hawaii, and
other destinations outside the U.S. and Canada, actual return shipping cost is paid by the owner.

What is not covered: This warranty does not cover correction of kit assembly errors. It also does not cover
misalignment; repair of damage caused by misuse, negligence, or builder modifications; or any performance
malfunctions involving non-Elecraft accessory equipment. The use of acid-core solder, water-soluble flux solder, or
any corrosive or conductive flux or solvent will void this warranty in its entirety. Also not covered is reimbursement
for loss of use, inconvenience, customer assembly or alignment time, or cost of unauthorized service.

Limitation of incidental or consequential damages: This warranty does not extend to non-Elecraft equipment or
components used in conjunction with our products. Any such repair or replacement is the responsibility of the
customer. Elecraft will not be liable for any special, indirect, incidental or consequential damages, including but not
limited to any loss of business or profits.

11

Front Panel

This reference section describes all front panel controls, the liquid crystal display (LCD), LEDs, and connectors.
Operating instructions are covered in later sections.

Control Groups

Primary Controls (pg. 13): These controls

provide basic transceiver setup, including power
on/off, band, operating mode, AF and RF gain and
squelch, ATU and transmit controls, display modes,
and menus.

Display (pg. 12): The LCD shows signal levels,
VFO A and B frequencies, filter bandwidth,
operating mode, and the status of many controls.
The VFO B display is alphanumeric, so it can show
decoded text from digital modes (CW, RTTY,
PSK31/PSK63), as well as menus, time and date,
help messages, etc.

Multi-Function Controls (pg. 14): The upper two
knobs set up receiver DSP filtering. The lower two
control transmit parameters, including keyer speed,
mic gain, speech compression, and power output
level. LEDs above each knob show which function
is active; tapping the knob alternates between them.
Pressing and holding these knobs (1/2 second or
longer) provides access to secondary functions.

Keypad (pg. 15): This group of switches is
numbered for use during memory store/recall and
direct frequency entry, but each switch also has
normal tap and hold functions. The upper row of
switches are VFO controls. The remaining rows
control receive-mode and miscellaneous functions,
such as noise reduction and text decode/display.

Memories (pg. 16): These switches control
frequency memory store/recall, message
record/play, and audio record/playback (with the
DVR). M1-M4 can also be used as up to eight
tap/hold programmable function switches.

VFOs (pg. 14): The large knob controls VFO A;
the smaller knob controls VFO B. The four
switches between the VFO knobs select tuning rates
and control related functions.

RIT/XIT (pg. 16): Three switches control RIT and
XIT on/off and clear (offset zero). The OFS knob
below the RIT/XIT switches selects the offset.

12

Display (LCD)

Multi-character displays: The 7-segment display

(upper) shows the VFO A frequency. The 13­segment display (lower) shows VFO B or text.

Bar graph, receive mode: The bar graph normally
acts as an S-meter. If CWT is turned on, the right
half of the S-meter becomes a tuning aid (pg. 36).

Bar graph, transmit mode: The bar graph
normally shows SWR and RF power output. The

RF scale will be either 5 and 10 (low power) or 50

and 100 (high power). In voice and data modes,
transmit scales can be changed to compression
(CMP) and ALC using METER.

VFO Icons: The TX icon indicates which VFO is
selected for transmit. In TX TEST mode, or when
TX is inhibited externally, TX flashes (see TEST).

Shows that VFO A or B is locked (see

LOCK

).

VFO A is the transmit VFO

VFO B is the transmit VFO; see

Filter Graphic: This shows the approx. bandwidth
and position of the receiver’s I.F. passband. See

Filter Passband Controls, pg. 25.

Filter Icons:

NTCH Notch filtering on (NTCH, pg. 27)

Manual notch (MAN, pg. 27)

I / II Shows selected preset (I/II, pg. 14)

XFIL Crystal filter selection (FL1-FL5)

Mode Icons:

Basic modes (LSB / USB, CW, DATA, AM, or

FM) are selected by tapping either end (Up/Down)

of MODE . Alternate modes (CW REV, DATA

REV, AM-S , FM +/-) are selected by holding

ALT. LSB and USB are alternates of each other.

+ icon on in SSB modes indicates ESSB (pg. 38).

T indicates FM/tone, CW/DATA text decode, or

AM-Sync auto-tracking.

Other Icons:

CWT CW/data tuning aid on (CWT, pg. 36)

DVR in use (AF REC / AF PLAY, pg. 16)

VOX VOX enabled (VOX, pg. 13)

QSK Full break-in CW enabled (QSK, pg. 32)

NB Noise blanker on (NB, pg. 15)

NR Noise reduction on (NR, pg. 15)

ANT Antenna 1 or 2 (ANT, pg. 13)

RX RX antenna in use (RX ANT, pg. 13)

ATT Attenuator on (ATT, pg. 15)

PRE Preamp on (PRE, pg. 15); flashes when

preamp2 is selected (pg. 25)

ATU ATU enabled (ATU, pg. 13)

RIT RIT on (RIT, pg. 16)

XIT XIT on (XIT, pg. 16)

SUB Sub receiver on (SUB, pg. 39)

SPLT Split mode in effect (SPLIT, pg. 38)

TX

A

TX

B

SPLIT

13

LEDs

TX [Red] Turns on in transmit mode.

∆ F [Yellow] The Delta-F LED turns on if

transmit and receive frequencies or modes are
different due to the use of SPLIT, RIT, or XIT.

[Green] Eight LEDs show which functions are

in effect for the Multifunction Controls (pg. 14).

(- )

(+) RIT/XIT OFFSET If the

OFS control is centered, or you tap CLR , the green
LED turns on (offset = 0). Otherwise, the yellow
(-) or (+) LED will be on, indicating the direction of
the offset. See RIT , XIT , and CLR .

Front Panel Connectors

PHONES You can use either mono or stereo

headphones at either the front- or rear-panel
headphone jack. Also see AFX (pg. 37).

MIC An Elecraft MH2, MD2, Proset-K2, or other
compatible mic can be used (see pinout below). To
select the front- or rear-panel mic, and to turn bias
on/off, use the MAIN:MIC SEL menu entry.

Bias must be turned on for electret mics (e.g. MH2,
MD2, Proset). It must be off for dynamic mics (e.g.
Heil mics using HC4 or HC5 elements).

Mic jack, viewed from front of K3

1 Mic audio, low-Z (~600 ohms)
2 PTT
3 DOWN button *
4 UP button *
5 FUNCTION button *
6 8V (10 mA max)
7, 8 Ground

* See CONFIG:MIC BTN menu entry.

FP ACC This connector (RJ-45, 6 pins) is located

on the bottom of the transceiver, near the VFO B
knob. At present it is used only for factory test.

Primary Controls

BAND Tap left/right end to move among ham

bands. CONFIG:BND MAP disables bands. For
“quick” band switching, see CONFIG:MEM 0-9.

VOX Selects voice-operated or CW keying-

operated transmit (VOX icon on), or PTT (VOX
icon off). Also see

DELAY (pg. 32) and CW

VOX auto-off control (CONFIG:CW WGHT).

QSK Selects either full break-in (QSK icon on) or

semi break-in keying, if VOX is selected in CW
mode. Also see

DELAY (pg.32).

MODE Tap the left or right end of this switch to

select the operating mode. When DATA is selected,
the DATA MD switch is used to specify DATA-A,
AFSK A, FSK D, or PSK D (pg. 33).

ALT In LSB mode, switches to USB (and vice-

versa). Also selects alternate modes, including:

CW REV, DATA REV, and AM-S (pg. 31). In
FM mode, selects + /- or simplex (pg. 31).

TEST Selects TX TEST (TX LCD icon flashing);

allows key/mic test without actually transmitting.

POWER Turns the K3S on or off. Note: To

ensure correct save of operating parameters,
turn the K3S off before turning the power supply
off.

MENU Displays MAIN menu (pg. 23).

CONFIG Displays the CONFIG menu (pg. 23).

XMIT Manually-operated transmit. Places the K3S

into transmit mode (same as PTT, pg. 28).

TUNE Puts out a carrier at the present power level.

Also TUNE Power Level (pg. 29).

RX ANT Enables the receive antenna (pg. 24). If

the sub RX is on, holding RX ANT alternates
between the sub’s MAIN / AUX antennas (pg. 39).

DISP Shows an alternate display on VFO B, such

as time, date, voltage, etc. (pg. 38).

METER Selects voice transmit bar graph modes:

SWR and RF, or CMP and ALC (pg. 30).

ATU TUNE Matches the antenna (transmitting at

up to 10 W) using the KAT3A ATU (pg. 24).

ATU Puts the ATU into normal mode (ATU icon

on) or bypass mode (pg. 24).

ANT Selects ANT 1 or 2 . In BSET mode with the

sub receiver on, selects MAIN or AUX antenna for
the sub receiver (pg. 39).

14

Dual-Concentric Potentiometers

AF — SUB AF gain controls for main
receiver (inner, or smaller knob) and sub receiver
(outer ring, or larger knob).

RF / SQL — SUB RF gain (and/or squelch)
controls for main and sub receiver.

Two menu entries are provided to control squelch
directly: CONFIG:SQ MAIN, and SQ SUB. They
can also be used to reconfigure the RF gain controls
as squelch for either receiver, and to select FM-only
or all-mode squelch. See Config Menu (pg. 57).

Multi-Function Controls

The upper two multi-function controls set up
receiver filtering. The lower two controls adjust
transmit settings. Each control has two primary
functions (white labels) and a secondary function
(yellow). Tap a control knob to alternate between
its primary functions, indicated by two LEDs. Hold
a knob (~1/2 second or longer) to select its
secondary function.

Filter Controls

The primary functions of the filter controls are:

SHIFT Shift passband either direction

LO CUT Adjust low-frequency response

HI CUT Adjust high-frequency response

WIDTH Adjust width of the passband

As these settings change, so does the filter graphic.
Crystal filters are selected automatically (or
manually using XFIL, pg. 15). Also see Filter
Passband Controls (pg. 25).

The secondary functions of these controls are:

NORM Normalize passband

Normalizing the passband sets the bandwidth to a
fixed, per-mode value (e.g. 400 Hz in CW mode)
and centers the passband. (Also see user-defined
normal settings, NORM1/2, pg. 26.)

I/II Select preset I or II (per mode)

Presets I and II each hold a continuously-updated
DSP/crystal filter setup (pg. 26).

Transmit Controls

The primary functions of the transmit controls are:

SPEED Keyer speed in WPM, 8-50 (8-100

if CONFIG:CW QRQ is ON)

MIC Mic gain
CMP Speech compression level
PWR RF output power in watts (pg. 28)

The present transmit mode determines which
primary functions normally apply; for example, in
CW mode, the SPEED / MIC control defaults to

SPEED . You can always tap a knob to override

the present selection.

The secondary functions of these controls are:

DELAY VOX delay (voice/data) or CW semi-

break-in delay, in seconds

MON Voice or data monitor level or CW

sidetone and alert tone level

You can optionally LOCK the MIC, CMP, and

PWR control settings; see CONFIG:PWR SET.

VFO Tuning Controls

VFO A controls the upper frequency display. This
is normally the RX and TX frequency. In SPLIT
mode, VFO B controls the transmit frequency (pg.

38). VFO B also controls the sub receiver (pg. 39).

The controls to the right of VFO A include:

FREQ ENT Direct frequency entry (pg. 15)

SCAN Start or stop scanning (pg. 42)

FINE Select 1 Hz tuning for both VFOs

and RIT/XIT offset

COARSE Select coarse tuning rate (pg. 24)

RATE Select one of two normal tuning rates

(10/50 or 10/20 Hz; pg. 24)

LOCK Lock VFO A (use BSET to lock B)

SUB Turn sub receiver on/off (pg. 39)

DIV Turn diversity mode on/off (pg. 40)

To link VFO B to VFO A, set CONFIG:VFO

LNK to ON. This is not necessary in diversity

mode, where VFO A always tunes both receivers.

VFO A can optionally be coarse-tuned using

the RIT/XIT offset control if both RIT and XIT are
off . See CONFIG:VFO OFS.

15

Direct Frequency Entry

To jump to any frequency within the tuning range
of the K3, tap FREQ ENT , then enter 1 to 3 MHz
digits, a decimal point, and 0 to 3 kHz digits.
Follow this with Enter ( . . ) to accept or

FREQ ENT to cancel. The decimal point is

optional if no kHz digits are entered, making it very
easy to get to the low end of most ham bands.

Examples:

1.825 MHz: FREQ ENT 1 8 2 5 . . .

1.000 MHz: FREQ ENT 1 .

50.100 MHz: FREQ ENT 5 0 . 1 .

For frequencies under 1 MHz, start entry with a
decimal point. If 4 or more digits are entered
without a decimal point, a value in kHz is assumed.

Keypad

Keypad switches have the tap and hold functions
listed below. They are also used for selecting quick
memories 0-9, and for direct frequency entry.

VFO Controls (Upper row)

The upper row of numeric keypad switches is used
to set up VFOs A and B. Their functions are:

A / B Exchange VFO A and B contents

BSET Set up VFO B and sub RX (see below)

REV Exchange VFO A and B temporarily

(repeater RX/TX swap in FM-RPT)

A B Copy VFO A frequency to VFO B;

tapping twice copies all other settings
(also see CONFIG:VFO B->A)

SPLIT Enable SPLIT receive/transmit

If cross-mode operation is not allowed for the
present VFO A and B modes, you’ll see SPL N/A
if you try to enable SPLIT. If cross-mode operation
is allowed, the mode icon for VFO B will flash as a
warning. Tap any switch to cancel the flash.

Holding BSET allows VFO B (and the sub
receiver, if on) to be set up directly (pg. 39). As
long as BSET is displayed, all VFO-related
controls and display elements apply to VFO B. An
alternative is to exchange VFOs with A / B , set up
VFO A, then exchange them again.

Receiver Control & Misc. (Lower Rows)

Receiver control functions normally apply to
VFO A/main receiver. If BSET is in effect, they
apply to VFO B (and the sub receiver if turned on).

PRE Preamp on/off; also selects preamp 2

if enabled on 12/10/6 meters (pg. 25)

ATT Attenuator on/off (5/10/15 dB, per-

band; hold switch for 2 seconds to go
directly to MAIN:ATTEN setting)

AGC AGC slow/fast (also see CONFIG:

AGC DCY, AGC HLD, and other

AGC menu entries)

OFF AGC off/on (when off, an AF limiter

is available; see CONFIG:AF LIM)

XFIL Select next available crystal filter

(see CONFIG:FLx ON)

APF CW: APF or Dual-passband filtering

(see CONFIG:DUAL PB);
RTTY: dual-tone filtering (pg. 32)

NB Noise blanker on/off (pg. 27)

LEVEL Noise blanker levels (pg. 27); use

VFO A knob to setup DSP blanker,
and VFO B to setup I.F. blanker

NR Noise reduction on/off (pg. 27)

ADJ Noise reduction parameter adjust; use

VFO B knob (pg. 27)

NTCH Notch filter auto/manual/off (pg. 27)

MAN Manual notch frequency (pg. 27); use

VFO B knob

SPOT Spot tone on/off (manual), or auto-

spot (if CWT is on; pg. 36)

PITCH CW sidetone PITCH, PSK pitch,

FSK / AFSK MARK tone and shift
(pg. 33), or FM tone setup (pg. 31)

CWT CW/data tuning aid on/off (pg. 36);

turn on to use auto-spot

TEXT DEC Text decode, CW or DATA (pg. 35);

use VFO B knob to select mode

AFX Audio effects on/off (pg. 37); use

CONFIG:AFX MD to set mode

DATA MD DATA mode selection (pg. 33); use

VFO B knob

16

Memory Controls

Frequency Memories

The K3S has 100 general-purpose memories (00-

99), plus per-band memories (M1-M4 on each
band). Each memory holds VFO A and B
frequencies, modes, filter presets, antenna selection,
and other settings. Each can have a text label of up
to 5 characters (A-Z, 0-9, and various symbols).

The Elecraft Frequency Memory Editor
software application can be used to simplify setup
and use of memories. Refer to our K3/K3S software
web page for details.

To store a general-purpose memory (00-99):
First tap V M (VFO to Memory), then locate the
desired memory using the VFO A knob. The VFO
A frequencies stored in each memory will be shown
as you scroll through them. When you reach the
desired memory number, tap V M again to store,
or tap M V to cancel the operation.

To recall a general-purpose memory: Tap

M V , then select memory 00-99 using VFO A.

Tap M V again to exit.

Memories 00-09 are quick memories, accessible
with just two switch taps. These could be used to
get to a starting point in each of 10 ham bands.
Memories M1 – M4 are per-band quick memories.
For example, you might set up M1 for each band’s
CW segment, M2 for the SSB segment, etc.

Memories 00-09 can act as if they were band

switches; see CONFIG:MEM 0-9.

To store or recall quick memories: Tap V M

or M V as before, but instead of rotating VFO A,
tap 0 - 9 or M1 - M4 .

To erase one or more memories: While scrolling
through memories to save or recall, tap CLR. Not
applicable to per-band quick memories (M1-M4 ).

To add or change a memory’s text label: First tap

M V , then select a memory (00-99) using VFO

A. Next, rotate VFO B to select each label position
in turn as indicated by the flashing cursor. Use VFO
A to change characters. After editing, tap M V
again. (Labels can be edited at any time, including
when you initially store a memory using V M .)

Adding an asterisk (*) at the start of a label
designates a channel-hopping memory (pg. 42).

Digital Voice/Audio Recorder (KDVR3)

The DVR can continuously record receive audio
(up to 90 seconds). To start/stop audio record, hold

AF REC . To start/stop playback, hold AF PLAY .

The

icon flashes during DVR use.

Playback position (0-90 sec.) is shown on the VFO
B display; “*” appears if you’re within the most
recent segment. Use VFO B to change the position.

For DVR voice message record/play, see pg. 31.

Message Record/Play Controls

Five switches provide record and playback of
outgoing messages: M1 , M2 , M3 , M4 and REC .
These switches provide single-tap play, hold-to­repeat, and other functions that are convenient for
contests and for sending often-repeated text or
voice messages during QSOs. CW messages can be
viewed and edited using K3 Utility, if desired.

For details on CW message record/play, see pg. 32.
The same messages can be used with CW-to-DATA
(pg. 36). For voice message record/play, see Digital
Voice Recorder (pg. 31).

M1 through M4 can alternatively be used as tap

or hold programmable function switches (pg. 23).

RIT and XIT Controls

RIT RIT (receive incremental tuning) on/off.

PF1 Programmable function switch (pg. 23)

XIT XIT (transmit incremental tuning) on/off.

PF2 Programmable function switch (pg. 23)

CLR Sets RIT/XIT offset to 0. Hold for 2

seconds to copy present RIT offset to VFO

A before clearing.

The RIT/XIT offset control sets the offset for RIT
and XIT. Three LEDs above the control show at a
glance whether an offset is in effect (pg. 11).

If CONFIG:RIT CLR is set to UNDO ON,

tapping CLR will alternate between 0.00 and the
last non-zero offset selected, if any.

17

Rear Panel

Connector Groups

The appearance of your rear panel may vary

depending upon the options installed.

Antennas: ANT1 (SO-239) is standard. ANT2

(SO-239) is supplied with the KAT3A ATU option,
which includes an antenna switch controlled from
the front panel. Both jacks are nominally 50 ohms
when the ATU is bypassed. AUX RF (BNC) is for
use with the KRX3A option; see pg. 39 and pg. 43.
ANT3 (BNC, on the KPA3A option panel) is the
antenna jack for the optional K144XV 2-m module.

DC: 12 VDC IN jack is an Anderson PowerPole
connector rated at 30 amps. (See Specifications, pg.
8, for detailed power requirements.)

12 VDC OUT (RCA/Phono) provides up to 1.0 A
(switched) for use with accessory devices.

Ground Terminal: A good station ground is
important for safety and to minimize local RFI.

KPA3A: This option panel is blank in the K3S/10
except for ANT3 (see above). In the K3S/100, the
blank panel is replaced with the fan panel shown,
which includes a circuit breaker.

KIO3B (pg. 19): Provides computer, auxiliary
control, and audio connections. The USB
connector handles both digitized line-level audio
and data (pg. 18). The RS232/P3 jack (RJ45) is
used with the P3 and/or for RS232 station control;
an RJ45-DE9 adapter is included (pg. 19).

KXV3B: Provides a variety of RF I/O signals,
including receive antenna in/out (pg. 41),
transverter in/out (pg. 41), a buffered I.F. output for
use with the Elecraft P3 (pg. 47), and internal I.F.
connections for the K144XV 2-m module. Preamp
2, for weak-signal work on 12/10/6 m, is also
included on this module (see pgs. 25 and 45).

External preamps such as the PR6-10 are not

needed with the K3S. See Preamp 2 (pg. 25).

Keying: PADDLE (1/4” jack) is the keyer paddle
input (see CONFIG:CW PDL). KEY (1/4” jack)
can be used with a hand key, external keyer,
computer, or other device. PTT IN (RCA/Phono) is
for use with a footswitch, etc. KEY OUT (RCA/
Phono) is the amplifier T-R relay keying output,
capable of keying up to +200VDC @ 5A.

REF IN (SMA): External 10-MHz reference input
for use with the K3EXREF option module (see
CONFIG:REF CAL and CONFIG:XVn OFS).

18

Control and Audio Connections

The K3S provides a full complement of station
control and audio interfaces on the KIO3B panel.
These interfaces are described in this section.

USB Port (Control and Audio)

The USB port can be used for computer-based
remote control. It also acts as the equivalent of a
built-in USB sound card, eliminating the need for
external converters and additional cables.

A single USB cable can handle all of these interface
requirements:

• commands from logging/contesting software

• line-level audio input/output (audio is digitized

by the KIO3B’s USB interface)

• PTT and CW keying (via “DTR” and “RTS”)

Most software applications will work with USB
instead of RS232. They will recognize the
transceiver’s USB port as a “COM” port, and/or as
a sound device, selectable from within the
application.

An Elecraft P3 Panadapter can be connected
directly to the K3S even when the USB port is used
with your computer. See details at right.

To connect a computer to the K3S via USB:

• Connect the supplied USB cable from the K3S

to any available USB port on your computer.
(See illustration below.)

• If you also have a P3, connect it to the

RS232/P3 port as shown, using an Elecraft
model CBLP3Y cable.

• Set the CONFIG:RS232 menu parameter to

USB. Exit the menu.

• With the USB cable plugged in and the K3S

turned on, determine which COM or sound
device ports have been assigned to the K3S.
This can be done from within applications. On
Windows PCs, an alternative is to locate the
Device Manager (Start > Control Panel >
System > Hardware), and view its list of Ports.
When you plug in the USB cable from the K3S,
a new COM port will appear in the list.

• If you plan to do PTT or CW keying from the

computer, see PTT and Keying (next page).

Optional: Using LINE IN/OUT jacks with USB

We recommend using the digital audio line-in/out
capability provided by the USB cable. The analog
LINE IN/OUT jacks can then remain unconnected.
See pg. 22 for further details on LINE IN/OUT.

19

RS232 / P3 Panadapter Port (RJ45)

The RS232/P3 port can be used with an Elecraft P3
Panadapter, or with a computer’s RS232 interface.

In most cases it is preferable to connect the
computer to the transceiver’s USB port as described
on pg. 18. However, RS232-only installations can
also be used, as discussed on this page.

An adapter cable to convert RJ45 to DE9 (RS232
standard, female) is supplied with the K3S (Elecraft

#E980297). This adapter allows you to connect the

K3S to a P3, or to a computer via a user-supplied
RS232 cable, as shown below. The adapter cable’s
DE9 connections are shown on the next page. RJ45
jack connections are shown below.

If you plan to use the RJ45 jack for PTT or keying
from the computer, see PTT and Keying (pg. 20).
Typically such connections would be made at the
DE9 end of the supplied adapter, rather than
directly at the RJ45 jack.

To connect a P3 Panadapter to the K3S, and
optionally connect a computer to the P3 (via
RS232):

• Use the supplied Elecraft #E980297 cable to

connect the P3 to the K3S as shown (see
illustration below). At the K3S end, the cable
is connected to the RS232/P3 jack. At the P3,
the cable connects to the XCVR jack.

• A computer can optionally be connected via

RS232 to the P3’s PC jack as shown. The cable
is user-supplied. (See DE9 signals, next page.)

• Set CONFIG:RS232 to 38400.

To connect a computer to the K3S via RS232,
without a P3 Panadapter:

• Connect the RJ45 end of cable # E980297 to

the K3S as shown below. Connect the DE9 end
to a computer, using an additional user-supplied
cable if required.

• Set CONFIG:RS232 to the desired baud rate.

20

RS232 Adapter Cable

The supplied Elecraft #E970297 cable converts
from RJ45 (at the K3S end) to DE9 (RS232
standard). The DE9 end can be connected to a P3’s
XVTR jack, or to a computer’s RS232 port. The
pinout for this end of the adapter is shown below.

If an additional RS232 cable is required to reach
your computer, it can be wired straight-through,
using as few as three wires (RXD, TXD, and
ground). DTR and RTS are optional.

This table uses EIA standard descriptions,

which are from the perspective of the PC.

Pin #

Description

1,6,8,9

Not used

2

RXD IN (data to PC from K3S)

3

TXD OUT (data to K3S from PC)

4

DTR (see PTT and Keying, below)

5

Ground (RF isolated)

7

RTS (see PTT and Keying, below)

RS232 adapter cable DE9 connections (female)

Serial Port Setup: Set CONFIG:RS232 for the

desired baud rate. Software should be set up at the
same rate; 8 data bits, no parity, 1 stop bit.

PTT and Keying (via DTR and RTS)

In the K3S, these are not used as serial I/O
handshaking lines. Instead, the K3S can use these as
PTT IN or KEY IN (see CONFIG:PTT-KEY). The
default for both signals is inactive. Refer to
application software documentation to determine if
it can use RS232 signal lines for PTT or keying.

Use these signals with caution. A computer
may assert DTR or RTS during power-up, causing
the K3S to transmit unexpectedly. If a computer or
other device asserts RTS or DTR while you’re
using the PTT-KEY menu entry, the K3S will enter
TEST mode as a precaution, allowing you to
change the menu setting if required.

ACC (Accessory I/O)

ACC connector pinouts are listed below.

ACC is not a VGA video connector. The K3S

does not provide a video output. (The P3 does

have an SVGA video output option; see pg. 47.)

Pin #

Description

1

FSK IN (see FSK Input)

2

AUXBUS IN/OUT (see KRC2 or XV­Series transverter instruction manual)

3

BAND1 OUT (see Band Outputs)

4

PTT IN (in parallel with MIC PTT)

5

Ground (RF isolated)

6

DIGOUT0 (see Transverter Control)

7

K3S ON signal (out) or TX INH (in)
(see Transverter Control, TX INH)

8

POWER ON (see pg. 46)

9

BAND2 OUT (see Band Outputs)

10

KEYOUT-LP (10 mA keying output)

11

DIGOUT1 (see DIGOUT1)

12

Ground (RF isolated)

13

BAND0 OUT (see Band Outputs)

14

BAND3 OUT (see Band Outputs)

15

EXT ALC input (see External ALC,
pg. 29)

ACC Connector (female, on KIO3B panel)

FSK Input (for FSK D Data Mode)

This is a TTL input pulled up to 5V, compatible
with PC outputs. When used with an RS232 signal
from the PC, a level translator is required.

DIGOUT 1

DIGOUT1 is a per-band/per-antenna output for
controlling external gear. See CONFIG:DIGOUT1.

21

Band Outputs (BAND0-BAND3)

BAND0-BAND3 are open-drain band selection
outputs, with internal pull-up resistors to 5 V. Their
behavior is controlled by CONFIG:KIO3B (see
below). Band data is based on VFO A’s frequency.

In tables below, 0 = pulled to ground (0 V). 1 =
floating to 5 V. External pull-up resistors can be
connected a voltage not exceeding 14 V.

With CONFIG:KIO3B set to NOR, the BAND0-3
outputs are mapped based on the selected HF-6 m
band as shown below. On transverter bands,
BAND0-3 will all be set to zero.

Band

BAND3

BAND2

BAND1

BAND0

160 m 0 0 0 1

80 m 0 0 1 0

60 m 0 0 0 0

40 m 0 0 1 1

30 m 0 1 0 0

20 m 0 1 0 1

17 m 0 1 1 0

15 m 0 1 1 1

12 m 1 0 0 0

10 m 1 0 0 1

6 m 1 0 1 0

If CONFIG:KIO3B is set to TRN, BAND0-3
reflect the parameters of the CONFIG:XVn ADR
menu entry, as shown below. On HF-6 m they’re
set to 0. Addresses INT. TRN0- 9 are used with
the internal 2-m transverter option (K144XV). INT

TRN0 sets all band outputs to 0, while INT
TRN1-9 have the same decodes as TRN1-9 .

Transverter addresses are also sent to Elecraft XV­series transverters and the KRC2 band decoder
accessory via the AUXBUS line. Note: TRN1-7
are sent as 1-7, but TRN8-TRN9 are sent as 0.

ADR

BAND3

BAND2

BAND1

BAND0

TRN1

0 0 0

1

TRN2

0 0 1

0

TRN3

0 0 1

1

TRN4

0 1 0

0

TRN5

0 1 0

1

TRN6

0 1 1

0

TRN7

0 1 1

1

TRN8

1 0 0

0

TRN9

1 0 0

1

With CONFIG:KIO3B set to HF-TRN, the
BAND0-3 outputs follow the NOR table when HF­6 m bands are selected, and the TRN table when a
transverter band is selected.

Transverter Control

Normally, when the K3S is turned on, a 5-VDC
logic signal appears on ACC pin 7 (K3S ON). This
could be used with Elecraft XV transverters as an
enable signal (pin 8 of J6 on the transverter).

However, pin 7 can alternatively be configured as a
transmit inhibit input line for use in multi­transmitter stations. (See TX INH, below.) In this
case it is not available as a power-on signal for
Elecraft transverters. Instead, the transceiver’s 12­VDC switched output could be used as a transverter
ON signal.

For transverter keying, you can use KEYOUT-LP
signal (pin 10 of the ACC connector) or the KEY
OUT jack (RCA).

With KIO3B set to TRN or HF-TRN, the
DIGOUT0 line (ACC, pin 6) will output 0 V when
low power mode is selected for the current
transverter band (CONFIG:XVn PWR). At all
other times, DIGOUT0 will be floating (Hi-Z).

TX INH (Transmit Inhibit Signal)

Pin 7 of the ACC connector can be configured as a
transmit inhibit input by setting CONFIG:TX INH
to LO=Inh (or HI=Inh). Holding pin 7 low (or
high) will then prevent transmit. An external 2.2 to
10 K pull-up resistor (to 5 VDC) is required.

If TX INH is set to OFF, pin 7 reverts to its

default output function, K3S ON (see above).

Elecraft KRC2 Universal Band Decoder

An Elecraft KRC2 can be used with the K3 to
perform station switching functions; it includes sink
and source relay drivers for all bands. The KRC2
obtains band data via the AUXBUS rather BAND0-

3. (See CONFIG:KRC2 for 6-m band mapping).
Refer to the KRC2 instruction manual for more
information.

22

SPKRS

STEREO or MONO; 4 to 8 Ω

Plugging in external speaker(s) cuts off the internal
speaker. A stereo plug is recommended; tip is left
speaker, ring is right. If you must use a mono plug,
set CONFIG:SPKRS to 1 to disable right-channel
audio. (This will result in mono headphone output,
as well, if you also set SPKR+PH to YES.)

If the speaker is not working with

headphones unplugged: Locate the CONFIG:

SPKR+PH menu entry. Tap 1 on the numeric
keypad until you see PH.R SW– (specifying
inverted logic for the rear headphone jack). This is
the default setting, required for the K3S.

PHONES

STEREO or MONO; 16 Ω min. recommended

The front and rear-panel headphone jacks are both
isolated with series resistors. This allows you to use
mono phones on one jack and stereo on the other, if
required. You’ll need stereo phones for AFX (audio
effects) and stereo dual receive (with sub receiver).

You can plug in headphones and speaker(s) at

the same time, and hear audio in both, if you set

CONFIG:SPKR+PH to YES. However, if you set
CONFIG:SPKRS to 1, setting SPKR+PH to YES

will result in mono output for both headphones and
speakers. You can set SPKRS to 2 if you use a
stereo plug at the external speaker jack, or if no
external speaker is plugged in.

MIC

MONO; hi- or low-Z

This jack accommodates an electret or dynamic
mic. Use MAIN:MIC SEL to select the rear panel
mic (RP). Tap 1 to turn on Low or High mic gain
range. Tap 2 to turn bias on/off (see pg. 30 for
recommendations based on mic type).

For the front-panel mic only, additional microphone
gain can be enabled by tapping 7 . Use this only for

very low-output mics. Not required for use with
the Elecraft MH2.

If the rear-panel mic has a PTT line, it can be
connected to either the PTT IN jack or the PTT
input on the ACC connector (pg. 20).

LINE IN

MONO, transformer-isolated; 600 Ω (nominal)

The LINE IN jack on the K3S can be connected to
your computer’s soundcard output. (It is preferable
in most cases to obtain line-in audio via the USB
cable. See pg. 18.)

If a plug is inserted into LINE IN at the K3S, this
line input will override the USB port’s line-in.

The MIC gain control on the K3S sets the line
input level when the MAIN:MIC SEL menu entry is
set to LINE IN.

The LINE IN level should be set carefully to

avoid transmit signal distortion due to
saturation of the input audio transformer. In

addition, computer sound card gain should be set 6
to 10 dB below the level at which the sound card’s
output stage starts clipping.

LINE OUT

STEREO, transformer-isolated; 600 Ω (nominal)

LINE OUT can be connected to your computer’s
soundcard inputs. (However, this is not necessary if
you’re using the USB port for line-level audio.)
Normally, the left channel is main receiver audio,
and the right channel is sub receiver audio (if
applicable). In this case the outputs are post-AGC
but pre-AF-gain.

Use CONFIG:LIN OUT to set the level, or to
switch from a fixed-level setting to =PHONES.

LIN OUT settings above 10 are usually not

necessary. This can in some cases cause

overloading of either the output transformers in the
K3S or the PC soundcard inputs (typically on noise
peaks). Either could degrade the performance of
demodulation software.

Some computers have only very high-gain,
high-impedance microphone inputs, not line-level
inputs. This can make it difficult to adjust the
LINE OUT level, and can also worsen noise
pickup. If a high-impedance mic input must be

used, you can add a resistive attenuator between the
K3S and the mic input to improve signal-to-noise
level.

23

Basic Operation

This section covers the fundamentals of K3S
receive and transmit operation. It’ll also get you
started using each of the major operating modes.

Once you’re familiar with the K3S, please go on to
Advanced Operating Features (pg. 35).

Using Tap/Hold Switches

Most K3S switches have two functions. Tapping
(pressing for less than 1/2 second) activates the
function labeled on the switch. Holding (pressing
for more than 1/2 sec.) activates the function
labeled beneath the switch.

Initial Power-Up

• Connect a power supply (pg. 8); antenna or

dummy load; key, if used (pg. 16); mic, if used,
and station ground (pg. 16).

• Tap POWER to turn the K3S on. The LCD

should illuminate and show VFO A and B
frequencies. (Tapping POWER again turns
power off.)

• The VFO B display can show a variety of

useful parameters in addition to the normal
frequency display. To see these, tap DISP (left
of the display), then rotate the VFO B knob.
The VFO B display will cycle through time,

date, RIT/XIT offset, supply voltage, current
drain, etc. (pg. 38). You can use these displays

to make sure the supply voltage is in range (11­15 V), and that current drain is about 1 amp
(higher with sub receiver installed and turned
on). Tap DISP to return to the normal VFO B
frequency display.

Using the Menus

There are two menus: MAIN and CONFIG. Most
entries in the CONFIG menu are used for test,
configuration, and alignment, and are used
infrequently.

Nearly all menu entries appear in alphanumeric
order. In the few exceptions to this, adjacent entries
are still closely related.

MAIN Menu

• Tap MENU to access the main menu. (Tapping

MENU again exits the menu.)

• Use VFO B to scroll through the menu entries,

referring to the list on pg. 55 for details.

• Change the value (or parameter) of any menu

entry using VFO A.

CONFIG Menu

• Hold CONFIG (hold function of the MENU

switch) to access the CONFIG menu. Holding

CONFIG for 3 seconds enters TERMinal mode

(for use with the K3/0-Mini panel; see pg. 47).

• Use VFO B to scroll through the CONFIG

menu entries, referring to the list on pg. 57.

Menu Help

While in the menu, tapping DISP shows help
information about the present menu entry. For most
entries, the default parameter value is shown in
parentheses at the start of the help text.

Programmable Functions

Menu entries that you’d like quick access to can be
assigned to any of the 10 programmable function
switches, PF1 , PF2 , and M1 – M4 (tap or hold).
“Function” menu entries can only be used via
such a switch assignment. (Examples, from the
CONFIG menu: VFO B->A and TTY LTR.)

To set up a programmable function switch, first use

MENU or CONFIG to locate the target menu entry.

Next, hold PF1 or PF2 ; or, tap or hold M1 – M4 .
For example, if you tap M2, you’ll see M2T SET
(T for tap), while holding M2 would show M2H

SET (H for hold). The assigned switch can then be

used as a shortcut to access that entry. M1 – M4 can
each be assigned a tap and/or hold function.

Any M1 – M4 switch that is used as a
programmable function switch will not be available
for message play. To cancel a programmable switch
assignment and restore a previously-saved message,
tap REC, then tap the buffer you’d like to restore
(M1 – M4), then tap REC again.

Macros

Programmable switches can also be used to
automate often-used sequences, or macros, such as
“SPLIT, A>B, move VFO B up 5.” Refer to the
CONFIG:MACRO x menu entry, K3 Utility help,
or the K3 Programmer’s Reference.

24

Band and Mode Selection

Tap either end of BAND to select the desired ham
band (160 through 6 meters). You can use direct
frequency entry (pg. 15), or recall a frequency
memory (pg. 16). Individual bands can be mapped
out if not needed (see CONFIG:BND MAP).

Tap either end of MODE to select the operating
mode. Hold ALT to select an alternate mode, if
required. This include CW REV (pg. 32), DATA

REV (pg. 33), AM- S (synchronous detection, pg.

31), and FM +/- (FM repeater split, pg. 31).

Antenna Selection and Matching

Main Antennas (ANT1 and ANT2)

With a KAT3A ATU installed, you can connect
antennas to both ANT1 and ANT2; tap ANT to
select. Holding ATU selects AUTO (autotune
enabled) or BYPASS mode. In AUTO mode
(ATU icon on), the antenna can be matched for best
SWR by tapping ATU TUNE. Up to 30 ATU
settings are saved for both antennas. See CONFIG:
KAT3 for instructions on clearing ATU memories.

The ATU icon will flash briefly whenever new
settings are automatically loaded.

Tapping ATU TUNE a second time within 5
seconds starts a more extensive match search. The
ATU can even be manually tuned if desired. Refer
to CONFIG:KAT3A for details.

Holding ANT allows names to be assigned to
ANT1 and 2 (e.g., ‘YAGI’). These will be flashed
when you switch antennas. When editing names,
VFO B selects the character position to change;
VFO A cycles through available characters. Setting
the first character to “- ” disables name display.

Receive-Only and 2-Meter Module Antennas

Tap RX to select the receive-only antenna (RX
ANT IN/OUT on the KXV3B module, pg. 41). The

KRX3A sub receiver either shares the main
receiver’s selected antenna or uses an auxiliary
input (see AUX RF, pgs. 39 and 43).

If a K144XV 2-meter module is installed, connect
its antenna to ANT3. (See K144XV manual.)

Automatic control of a KAT500 ATU

The K3S can automatically recall settings for a
connected KAT500 ATU as the VFO is tuned. See
CONFIG:KAT3A and the KAT500 owner’s manual.

Using the VFOs

VFO A is both the main receive and transmit
frequency, except during SPLIT, in which case
VFO B controls the transmit frequency (pg.38).
VFO B also controls the sub receiver (pg. 39).

Tap RATE to select 10 / 50 Hz per step. The faster
rate can be changed using CONFIG:VFO FST.
The number of counts (or steps) per VFO knob turn
can be changed using CONFIG:VFO CTS.
Tapping RATE briefly flashes either the 10-Hz or
100-Hz digit to indicate slow or fast tuning.

For 1-Hz steps, tap FINE ; for wider steps, use

COARSE (CONFIG:VFO CRS sets coarse steps

per-mode). When FINE is in effect, a 1-Hz digit
will appear in the VFO A display. When COARSE
is in effect, the 10-Hz digit is not shown.

Tap A B once to copy VFO A’s frequency to
VFO B. Tapping A B a second time within 2
seconds also copies VFO A’s filter setup, preamp
state, and other settings to VFO B.

A / B exchanges VFO A and B and their settings.

(Also see CONFIG:VFO B->A.) Pressing REV
only exchanges the VFOs for as long as you hold
it in. (Exception: When using an FM repeater
offset, REV permanently swaps RX/TX.)

VFO B and the sub receiver can be set up directly
by holding BSET. While B SET is in effect, all
icons and VFO-related controls apply to VFO B
(and to the sub receiver, if turned on; see pg. 39).

Holding SUB turns on diversity mode (pg. 39).

RIT and XIT

The RIT/XIT offset control, at the far right, sets the
offset for RIT and XIT. The offset is shown on the
VFO B display as you adjust the control. Three
LEDs show whether the offset is 0, (-) or (+).

Tap CLR to zero the RIT/XIT offset. Tapping it a
second time restores the offset.

To copy the present RIT offset to VFO A, hold

CLR for 2 seconds. VFO A will be moved to the

new frequency before the offset is zeroed.

If RIT/XIT are both off, the offset control can

coarse-tune VFO A (CONFIG: VFO CRS). Coarse
tuning steps are programmable by mode.

25

Receiver Setup

This section explains how to use basic receiver
controls. Setup for specific operating modes is
described in later sections; see Voice Modes (pg.

30), CW Mode (pg. 32), and Data Modes (pg. 33).

Also see Text Decode and Display (pg. 35) and

Audio Effects (pg. 37).

Receiver Gain Controls

Use AF — SUB (pg. 11) to set the desired main
and sub receiver volume level. There are two
overall audio volume ranges, LO and HI, which can
be selected using CONFIG:AF GAIN.

Usually, both RF — SUB controls will be set
fully clockwise (main and sub receiver RF gain).
You may wish to reduce RF gain to optimize
receiver response to high signal levels or noise.

If sub RF gain has been configured as squelch

for both receivers, then main RF gain will control
RF gain for both. (See CONFIG:SQ MAIN.)

Preamp and Attenuator Controls

Tap PRE to turn on preamp 1 (+10 dB). On 12-6 m,
a second tap turns on preamp 2, a +20 dB, ultra
low-noise preamp for weak-signal work. The PRE
icon flashes when preamp 2 is selected. Use
CONFIG:PREAMP2 to enable preamp 2.

Hold ATT to turn on the attenuator. The main
receiver has 5/10/15 dB settings, selectable per­band via the MAIN:ATTEN menu entry. (Holding
the ATT switch for over 2 seconds also takes you
directly to this menu entry.) The sub RX has a 10­dB attenuator, switchable in BSET mode (pg. 39).

Crystal Filter Selection

You can install up to five crystal filters in the main
and sub receivers. For diversity receive, matched
filters should be used (pg. 40). Bandwidths as
narrow as 200 Hz are available. See Appendix A for
recommended filter bandwidths for each mode.

To select a crystal filter manually, tap XFIL. The

FL1-FL5 icons show the current selection. This

sets the DSP passband to match the crystal filter,
and removes any passband shift or lo cut/hi cut. The
K3S will also select appropriate crystal filters
automatically as you adjust the SHIFT,

WIDTH, LO CUT, and HI CUT controls.

Filter Passband Controls

As you rotate the filter controls (shift, width, lo cut,
hi cut), the associated parameter value is shown on
VFO B. The filter graphic shows the width and
location of the passband, as illustrated below. In
these specific examples, segments that turned off as
a result of control movement are shown in gray.

High Cut

Low Cut

Width

Shift

Filter passband controls don’t apply in FM
mode. SHIFT control granularity can be set to
either 10 or 50 Hz in CW and DATA modes; see
CONFIG:PB CTRL. In Sync AM mode (AM- S),
SHIFT selects the upper or lower sideband.

Each passband control has an integral switch. These
switches are used as follows:

Tapping the control alternates between the two
primary functions for that control, for example
HI CUT and WIDTH. This is indicated by the
two LEDs above each control.

Holding a control activates its secondary
function, labeled below the control.

Tapping or rotating a control shows the present
setting. To see the settings of both knob functions
without changing them, just tap the control twice.

The secondary functions of the controls are NORM
and I/II, described in the following sections.

26

Filter Presets (I/II)

Each operating mode provides two “floating” filter
presets, I and II, which store filter settings on a
per-VFO, per-mode basis (excluding FM). They are
updated continuously as you change filter settings.
Fixed (non-floating) per-mode filter settings are
also available, as explained below.

You can alternate between the I and II settings by
holding the I/II switch. This is especially useful
when you’re alternating between wide and narrow
settings during contest or DX operation.

Filter Normalization (NORM)

Standard Settings

To get quickly to a standard per-mode bandwidth
and reset any passband shift or cut, hold NORM
(normalize). The normalized AF bandwidth is 400
Hz in CW and DATA modes, 2.7 or 2.8 kHz in SSB
modes, and 3.0 kHz for AM1.

Whenever you normalize the filter passband,
two small "wings" appear at the left and right ends
of the DSP filter passband graphic as shown below.

Moving any DSP control makes the "wings"
disappear, as a reminder that the passband is no
longer normalized.

1

In AM mode, the I.F. bandwidth required for good

fidelity is about twice the AF bandwidth. This is why a 6
kHz or wider crystal filter is needed to effectively use the
3 kHz NORM setting. If an FM filter is installed, it can
be used in AM mode to provide good fidelity at even
higher AF bandwidth settings.

Custom Settings (NORM1 and NORM2)

In addition to the standard "NORM" values, you
can save two of your own setups in each mode, then
recall them using the NORM function. These setups
are referred to as NORM1 and NORM2.

To save a custom normalization setting:

• set up the filter passband as desired for the

current mode

• hold NORM until you see <

-

SAV -> (3

seconds)

• rotate the knob slightly left or right to save it as

NORM1 or NORM2.

(The arrows to the left and right of SAV are a
reminder that you can rotate the knob to get to the
two user-defined normalization settings.)

To recall, hold NORM until you see <

-

NOR ->

(about 1/2 second), then rotate the knob left or right
to recall NORM1 or NORM2.

Narrow DSP Filter Selection

For bandwidth settings of 100 Hz or lower, the DSP
normally uses a type of filter that minimizes
ringing: the Finite Impulse Response or FIR filter.

If you’d like steeper filter skirts, and don’t mind a
small amount of ringing, you can select Infinite
Impulse Response” or IIR filters for these
bandwidths. Locate CONFIG:FLx BW menu entry,
then tap 7 until you see IIR ON. Both main and
sub receivers will use the same setting.

IIR filters take longer to change from one
bandwidth to another, so you may hear audio
artifacts when adjusting the DSP controls. If this is
objectionable, use the default FIR filters.

Another narrowband filter alternative in CW
mode is APF (audio peaking filter). This filter has a
very narrow peak (~30 Hz) but very little ringing
due to its broader skirts. See APF, pg. 32.

27

Reducing Interference and Noise

The K3S provides several ways to cut interference,
including DSP noise reduction, manual and auto
notch, and noise blanking. Also see Audio Effects
(AFX, pg. 37).

There are actually two noise blankers: one at the
first I.F. (KNB3 module), and the other at the 2nd
I.F. (DSP).

Noise reduction, noise blanking, and notch

filtering should only be used when necessary. These
signal processing techniques are very effective, but
can introduce side effects. Sometimes, reducing the
filter bandwidth is the most effective interference­reduction strategy.

Noise Blanking

Tap NB to enable I.F. and/or DSP noise blanking.

Next, hold LEVEL to set the DSP level (VFO A)
and I.F. level (VFO B). You’ll initially see DSP

OFF and IF OFF on the VFO A and B displays.

Rotating VFO A clockwise will turn on the DSP
NB, showing DSP t1-1 through DSP t3-7 . The
first number shows the relative pulse integration
time, and the second shows the blanking level. The
higher the numbers, the more aggressive the DSP
blanking action.

Rotating VFO B clockwise will turn on the IF NB,
showing IF NARn, IF MEDn, or IF WIDn,
where n is 1 -7 . NAR/MED/WID refers to narrow/
medium/wide blanking pulse widths, and n is the
blanking level. Higher n means more aggressive
blanking action. Use NAR width when possible to
minimize strong-signal interaction effects.

The NB icon will flash slowly if the I.F.
blanker setting is too high for the present signal
conditions. If this happens, use a lower setting.

Both the DSP and IF blanking settings are saved on
a per-band basis. If CONFIG:NB SAVE is set to

YES, the on/off status of NB will be also be saved

for each band.

The DSP noise blanker is in the 2nd I.F., where
it can’t be activated by signals outside the crystal
filter passband. It can be used with high-duty-cycle
and complex-waveform noise generated by
computers, switching power supplies, light
dimmers, etc. The I.F. noise blanker is in the 1st
I.F., where it can use very narrow blanking widths.
It is most effective at blanking AC line noise,
lightning, and other very broadband noise. Often, a
combination of the two is the most effective.

Noise Reduction

Noise reduction reduces random background noise
while preserving meaningful signals. It adds a
characteristic “hollow” sound to all signals.

NR turns noise reduction on. It doesn’t apply to

DATA or FM modes, or with AGC turned off.

Hold ADJ to display the NR setting, which is
saved per-mode. Use the VFO B knob to tailor NR
for the present band conditions. In general, the
higher the number, the more aggressive the noise
reduction. Settings F1- 1 through F4- 4 are
recommended. F5- 1 through F8- 4 use a different
algorithm, where the -x part of the setting indicates
the degree of mix between the DSP-processed and
unprocessed signals (-1 is about 50% processed, - 4
is 100%). A small M appears to remind you that a

M ixed setting is in effect, e.g. NR

M

F5- 1.

Notch Filtering

Notch filtering removes interfering carriers while
leaving the desired signal relatively unaffected. The
K3S provides automatic and manual notch tuning.

Auto notch will find and remove one carrier, and in
some cases more than one. (SSB mode only.)

Manual notch removes one carrier at a specified
pitch, and can be used in CW and DATA modes as
well as voice. Since manual notching sets up a fixed
(rather than adaptive) notch, it can even suppress a
keyed carrier, i.e. a Morse code signal.

Tap NTCH to turn on notch filtering (NTCH icon).
This turns on Auto notch in SSB mode, and
Manual notch in other modes (adds icon).

Holding MANUAL directly selects manual notch in
any mode. Adjust the manual notch frequency using
VFO B, then tap NTCH again to exit.