Elecraft KPA1500 Users Manual

ELECRAFT

1500-WATT AMPLIFIER

OWNER’S MANUAL

Revision A1 (Draft), August 9, 2017

E740301

Copyright © 2017, Elecraft, Inc.

All Rights Reserved



KPA1500

WARNING

Dangerous Voltages

Inside the KPA1500

Before opening the KPA1500 RF Deck or Power Supply
enclosures:

1. Turn off the KPA1500 by tapping the front panel ON
switch and wait until the fan stops. (The fan drains
the power supply to a safe voltage.)

2. Disconnect the Power Supply at RF Deck rear panel
before opening the RF Deck enclosure.

3. Disconnect the Power Supply from the mains before
opening the cover.

Key to Symbols Abbreviations and Text Styles

Important – read carefully

Operating tip

TEM P

PK H O L D

LED Light Emitting Diode

LCD Liquid Crystal Display

Follow the instructions under a Caution to avoid damage to the equipment.

Follow the instructions under a Warning to avoid serious personal injury.

Tap switch function (labeled above a switch; press for less than 1/2 second)

Hold switch function (labeled below a switch; press for at least1/2 sec. to

activate)

CAUTION

WARNING

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Introduction

On behalf of our entire design team, we’d like to thank you for choosing the Elecraft KPA1500 amplifier.

The KPA1500 offers a unique combination of features. It’s one of the smallest 1500-W amplifiers available. The
power supply is in a separate enclosure for ease of station layout.

The KPA1500 is capable of fully automatic operation, yet has an alphanumeric display and a full complement of
front panel switches for precise manual control. A comprehensive remote-control command set is also included.

The KPA1500 can be used with nearly any transceiver, thanks to its instantaneous RF-based band switching,
advanced protection circuitry, adjustable ALC, and extensive parametric monitoring. It also has inputs that
allow direct band switching from many popular transceivers. T/R is completely noise-free thanks to the use of
PIN-diode switching.

The KPA1500 comes with a built-in Automatic Antenna Tuner (ATU) that can handle a load SWR up to 3:1 at
full 1500 watt output in any mode.

Of course the KPA1500 is an ideal companion for the Elecraft K3 transceiver, both physically and electrically.
The K3 can sense whether the amp is in standby or operate mode, then select the appropriate per-band power
settings. This allows you to set up the K3 for “barefoot” operation at one power level on each band, and then
switch the amp to operate and set up optimal drive levels for full 1500-W output. The K3/KPA1500
combination is also capable of extremely fast break-in, especially when the K3 is placed in QRQ (high-speed
CW) mode. The two are so well-integrated that you can use the per-band switches on the amplifier to change
bands at the transceiver.

If you use the KPA1500 with both the K3 transceiver and P3 panadapter – our new “K-Line” – you’ll enjoy a
high degree of operating convenience, along with world-class performance and the power to get the job done.

73,

Wayne, N6KR

Eric, WA6HHQ

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FCC-Mandated Part 15 Notice:

This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions, may
cause harmful interference to radio communications. However, there is no guarantee that interference
will not occur in a particular installation. If this equipment does cause harmful interference to radio or
television reception, which can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the following measures:

- Reorient or relocate the receiving antenna.

- Increase the separation between the equipment and receiver.
– Connect the equipment into an outlet on a circuit different from that to which the receiver is

connected.

– Consult the dealer or an experienced radio/TV technician for help.

Regarding the computer interface: changes or modifications not expressly approved by Elecraft could
void the user's authority to operate this equipment.

Elecraft Inc.
125 Westridge Dr.
Watsonville, CA 95076

[phone]

www.elecraft.com

4

Installation

Installation consists of the following:

 Positioning the KPA1500 RF Deck and Power Supply to provide for proper cooling (pg 6).

 Connecting the KPA1500 RF Deck and Power Supply (pg 6)

 Cabling the KPA1500 RF Deck to your other station equipment (pg 6).

The KPA1500 rear panel is shown in Figure 1. The connectors and controls are described following the figure.

Figure 1. KPA1500 Rear Panel

and SO-239 RF connectors to antenna system or dummy load.

SO-239 connector for RF input from the driving transceiver.

Low level KPA1500 transmit signal output.

Station ground attachment.

High voltage connection to the KPA1500 power supply.

Control circuit connection to the KPA1500 power supply.

Accepts a 12V input for remote control applications to power the KPA1500 on or off.

Negative-going voltage for transceivers that require ALC. (Elecraft transceivers do not require this

connection.

Enables the KPA1500 by a short to ground. 5 Vdc open circuit inhibits the KPA1500 . When grounded the

source must sink 1mA to enable the KPA1500.

For interconnecting cable to fully integrate the KPA1500 with an Elecraft K3 or K3S for enhance mode

operation.

Input signal to the internal KPA1500 automatic antenna tuner (ATU) that emulates an Icom remote ATU

when the KPA1500 is used with Icom transceivers.

RS232 level serial data connection for use with the KPA1500 Utility program and other computer-based

applications

Ethernet connection for local or remote operation applications.

USB connection to virtual COM port for use with the KPA1500 Utility and other computer-based programs.

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Positioning the KPA1500 RF Deck and Power Supply

Provide at least 4 inches (10 cm) clearance behind the fans and at least 1 inch (2.5 cm) clearance around the top,
bottom and sides for normal cooling air flow.

The supplied cables allow the power supply and RF deck to be placed up to 66 inches (167 cm) apart. The
Power Supply can be operated remotely and so need not be positioned within reach of the operator. The fans
operate whenever the KPA1500 is on, so you can place the power supply under the operating desk or elsewhere
to minimize the sound of the fans.

Cabling – Power Supply

A mains power cable is provided that plugs into the Power Supply. The other end has bare wires for you to add
the 240 VAC connector needed to match your mains outlet.

Connect the Power Supply to the RF deck with the supplied 66-inch (167 cm) cable that has an Anderson
PowerPole® connector and a 12-pin connector at each end.

Plug the PowerPole connector tnto the HV Supply connector ( ) on the RF Deck rear panel (see Figure 1) and
the corresponding connector on the Power Supply. Observe the polarity; match the colors on the plug with the
connectors

Connect the 15-pin connector to the Power Supply and the Control connector ( ) on the RF Deck rear panel.

Cabling – RF Deck

Always turn the KPA1500 off before attaching or removing cables.

The KPA1500 may be used with the Elecraft K3, K2 or any HF/6 meter transmitter and that has a KEY IN
output meeting the requirements shown under note 4 below. Interconnections with the transceiver are shown in
Figure 2. The driving transceiver must provide up to TBD watts of RF drive for full output and the output power
must be adjustable as described under Transmitting on pg 11.

The optional KPAK3AUX cable provides closer integration with the K3 by sharing band information between
the KPA1500 and the transceiver (see Figure 3). The KPAK3AUX cable provides all the operational features
described under Operation, including coordinated band-switching (pg 11). The KPAK3AUX cable includes the
KEY IN line. If you need access to this line so that other equipment can control the amplifier, you can install the
Key Line interrupter supplied with your KPAK3AUX cable set and use a separate key line as shown in Figure 4.

You must use the Key Line Interrupter when using a separate key line with the
KPAK3AUX cable set. Otherwise any external equipment inserted into the key line will not
be able to inhibit the amplifier.

You can make cables for use with Yaesu and Icom transceivers that also provide closer integration with the
KPA1. For details of those cables and the KPAK3AUX cable set see AUX Connector Interface on page 22.

NOTE

1. Connect your station ground to the GND wing-nut . A good station ground is important for safety and

to minimize local radio frequency interference (RFI).

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2. Attach the RF INPUT to the output of your driving transceiver or transmitter using a 50 ohm coaxial

cable with a PL-259 male connector on the KPA1500 end.

3. Attach the RF OUTPUT to a suitable load with an SWR of less than 1.5:1. A dummy load is strongly

recommended for initial testing.

4. The driving transmitter must ground the KEY IN line circuit during transmit while sinking up to 1 mA.

If the transmitter Key Output is not a contact closure or equivalent, it must be at a level between +4 and
+16 VDC during receive. (Compatible with all known transmitters. No key line buffer required.)

Figure 2. Basic Cabling Diagram for Any Transceiver.

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Figure 3. K3S Enhanced Cabling Using KPAK3AUX Cable.

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