Elecraft K160RX User Manual

ELECRAFT K160RX 160 METER MODULE

WITH RECEIVE ANTENNA SWITCH

Assembly and Operating Instructions

Revision D, Oct. 10, 2006. Copyright © 2000, 2006, Elecraft; All Rights Reserved

Introduction

The K160RX adds the 160-m band and a receive antenna switch to the Elecraft K2. The antenna switch
functions on all bands, but is especially useful on 160 m where a low-noise receive antenna is often used.
Preamp and attenuator settings used with the receive antenna are saved on each band (see pg. 10).

The K160RX plugs directly into the K2's RF board, and requires no wiring other than a short lead to the
receive antenna jack. Once the module is installed, the 160-meter band will become available using

BAND+ and BAND- or via direct frequency entry. Also, the RANT menu entry (receive antenna) will be

activated.

Latching relays are used for both the 160-meter low-pass filter and the receive antenna switch. These
relays consume no power except when actually being switched on or off, so the K160RX module does not
increase the current drain of the K2. Please refer to the schematic diagram at the end of the manual for
circuit details.

Specifications

160 m Frequency Range 1.8 to 2.0 MHz

Power Output 10 watts (nominal), adjustable to below 0.5 W

Receive Antenna Switch

Impedance 50 ohms
Isolation > 50 dB between RX ant. jack and main antenna jack (J4)
Applicability All bands (independent selection on each band)

Current Drain 0 mA

Size 2.6 x 0.8" (6.6 x 2 cm)

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The VFO will typically tune down to about 1.4 MHz. This extended receive coverage is useful for
receiving stations in the high end of the A.M. radio band, although the band-pass filter will significantly
attenuate signals below 1.8 MHz.

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Parts Inventory

The table below lists all parts in the kit. If you have trouble identifying any of these items, consult the

K2 Owner's manual, which has photographs of similar parts.

Ref. Description Part # Qty.

Components on K160RX Module

C4,C5,C6 Capacitor, .001 µF disc or monolithic (“102”) E530001 3
C1,C3 Capacitor, 1500 pF NPO or C0G, monolithic (“152”) E530002 2
C2 Capacitor, 2700 pF NPO or C0G, monolithic (“272”) E530003 1
K1,K2 DPDT latching relay, 5 V (“G6HU-2”) E640001 2
L1,L2 Toroidal inductor, approx. 5 µH, 21 turns on T44-1 or T50-1

core (blue). (Either a T50-1 or T44-1 core can be used with the

same no. of turns.)
P1 Conn., 16 pin male, 0.1" spcg., gold E620002 1
MISC #26 enamel wire E760002 3 ft.
MISC #24, Wire, Insulated, Stranded E760001 6 in.
MISC PC Board, K160RX E100088 1

Components on RF Board

C68 Capacitor, 10 pF NPO disc E530006 1
C153 Capacitor, 68 pF NPO disc E530007 1
C75 Capacitor, 470 pF NPO disc or monolithic (“471”) E530004 1
C13,C14 Capacitor, 1200 pF NPO disc or monolithic (“122”) E530005 2
J14 Conn., 16 pin female, 0.1" spcg., gold E620003 1

Hardware andMiscellaneous

K160-J1 Panel-mount BNC connector E620001 1

HDWR #4 split lock washer (includes 3 spares) E700004 8
HDWR 4-40 x 1/4" ZN ST phillips machine screw E700005 2

E680001 2

HDWR 3/16" dia. x 5/8" long round 4-40 threaded standoff E700003 1

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Assembly

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A fine-point, temperature-controlled soldering iron is required to assemble this kit. A high-

wattage iron may damage components, pads, or traces.

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In the following steps you'll be installing the latching relays (K1 and K2). Relay pins must not be

bent or trimmed as this may cause unreliable mechanical operation.

Place relays K1and K2 on the top side of the 160 meter PC board (component side). One end of each

relay has a heavy line printed across the top to indicate the pin 1 end. This end must be matched with the

same end of the relay’s PC board outline. Do not solder the relays yet.

Solder only two pins on each relay, at opposite corners. Do not bend or clip relay leads.
Verify that the relays are in the correct orientation and are seated flat on the board, then solder all of

the remaining relay pins.

Install all of the capacitors (C1-C6), bending the leads out slightly on the bottom to hold them in
place. Trim the leads to about 1/16" (1.5 mm) long before soldering to insure that the leads do not come
into contact with the toroids on the main board.

Inductor L1 is wound on a T44-1 or T50-1 toroidal core (blue) using 17 inches (43 cm) of #26 enamel

wire. To wind the inductor, “sew” the long end of the wire through the core exactly 21 times. Each pass
through the core counts as one turn. The finished winding should look very similar to the drawing below,

but with 21 turns rather than 14.

Remove insulation

Verify that the turns of L1 are not bunched together. They should occupy about 85% of the core’s

circumference as shown above.

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Cut L1's leads to about 1/2" (12 mm) long. Completely remove the enamel insulation from the leads

to within 1/16” (1.5 mm) of the core. To remove the insulation, use your soldering iron tip (and a little

solder), a butane lighter, or sand-paper. If you scrape the insulation off, be careful not to nick the wire.

Install L1 flat against the PC board as shown by its component outline, then pull the leads taut on the

bottom of the board. Note: The correct holes for L1's leads are both just to the right of the component
outline. Do not use the hole near the "L1" label.

Trim and solder the leads of L1. When soldering, make sure that the solder binds well to the leads. If

the lead appears to be an “island” in a small pool of solder, chances are it is not making good contact. It’s a

good idea to measure from pad to pad using an ohmmeter to be sure the leads are making contact.

Wind and install L2 in exactly the same way as L1.

Install 16-pin male connector P1 on the bottom of the PC board in the position indicated by its
component outline. Do not solder yet. The drawing below shows how P1 should appear viewed from the
left end of the board, with the notch towards you and the component side up.

Componen ts on top

P1 (onbo ttom)

Solder just one pin of P1, near the middle of the connector (close to relay K1 on the top side of the
board). Be careful not to touch K1's plastic case with the soldering iron.

Verify that P1 is now perpendicular to the PC board and is seated completely flat. If not, re-heat the
soldered pin and press down on all of P1's pins until the connector drops into place. Once the connector is
seated correctly, solder the remaining 15 pins.

Cut a 1.5" (3.8 cm) length of hookup wire. Remove 1/4" (6 mm) of insulation from each end.

Solder one end of this wire to the pad labeled "RX" near the notch in the 160-m PC board. The other
end will be connected to the center terminal of the receive antenna jack (K160-J1) in a later step.

Prepare a second 1.5" (3.8 cm) wire. Solder one end of this wire to the ground pad just to the left of
C5 on the 160-m PC board. This pad is not labeled. The other end will later be connected to the solder lug
of the receive antenna jack.

Inspect the 160-meter module for solder bridges or cold solder joints, especially around P1.

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