Elecraft KPA500 User Manual

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LECRAFT

KPA500

500-W

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Copyright © 2011, Elecraft, Inc.

ATT AMPLIFIER

WNER’S MANUAL

Draft, March 3, 2011

All Rights Reserved

Contents

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

Installation ................................................................................................................................................4

Operation ..................................................................................................................................................7

Power On ..................................................................................................................................................... 7

Band Switching............................................................................................................................................ 8

Transmitting................................................................................................................................................. 8

Monitoring ................................................................................................................................................... 9

Fault Conditions..........................................................................................................................................10

Menu...........................................................................................................................................................11

Firmware Updates...................................................................................................................................12

Specifications..........................................................................................................................................13

Customer Service and Support ...............................................................................................................14

Theory of Operation ...............................................................................................................................15

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Key to Symbols Abbreviations and Text Styles

Important – read carefully

Operating tip

TEMP

PK HOLD

LED

LCD

Tap switch function (labeled above a switch)

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

Light Emitting Diode

Liquid Crystal Display

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Installation

The following text uses braces to refer to numbered elements in the front- and rear-panel illustrations below. For
example, {1} refers to 1, the

RF OUTPUT

Figure 1. KPA 500 Rear Panel

connector.

Mains Voltage Settings

CAUTION!

Do not connect mains power to your KPA500 or attempt to turn it on before
setting the fuse block switch and internal jumpers to match your supply
voltage as described below; otherwise you may do extensive damage to your
amplifier.

1. Check to ensure the fuse block {4} is set for either 120 VAC or 240 VAC to match your mains voltage.

The current voltage setting is shown in the red window. If needed, change the fuse block setting as
follows:

• Open the door covering the fuse block and then carefully pry the red fuse block out of the holder as

shown below:

• Install the proper fuses in the block. Use 12A fuses for 115V and 6A fuses for 230V.

• Replace the fuse block so that the correct mains voltage appears in the window in the cover.

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2. Set the internal transformer tap for the specific voltage within the 120 or 240 VAC ranges as follows:

• Remove the 14 screws securing the KPA500 top cover as shown below. Do not remove the screw

indicated. It is part of the safety interlock switch mechanism. Lift the top cover off.

• Three taps are provided via red, green and yellow wires. Choose the tap according to the actual

mains voltage at the outlet you plan to use for the KPA500. If you cannot measure your mains
voltage, use the yellow tap.

115V Nominal Mains TAP 230V Nominal Mains

95V to 105V GREEN 190V to 210V
106V to 115V RED 211V to 230V
115V to 125V YELLOW 231V to 250V

• Be sure to place the unused taps side-by-side on the terminals at the back panel as shown. Do not

leave them floating loose inside the unit.

• Replace the top cover before proceeding. An interlock switch prevents operating the amplifier with

the top cover removed.

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3. Test the power supply voltage output as follows:

• Connect the mains supply cable to {15} on the rear panel and plug the cable into the mains outlet.

(At this point this may be the only cable connected to the rear panel.)

• Position the rear-panel power switch to On (I).

• Tap the front panel ON switch. The LCD should light.

• Tap the HV switch ({3} on Figure 2) and note the voltage displayed on the LCD. It must be between

65 and 80 volts. If it is outside of this range, immediately tap the ON switch to turn the KPA500 off,
and position the rear panel power switch to Off (O). Open the top cover again and select a different
transformer tap. If the voltage was too low, select a tap further up the list in the above table. If the
voltage was too high, select a tap further down the table.

NOTE: If the red FAULT LED lights when you tap the
power supply voltage is above the upper limit. Use a power transformer tap lower on the
above table and retry the test.

Cabling

1. Connect your station ground to the

safety and to minimize local radio frequency interference (RFI).

2. Attach the

RF INPUT

{11} to the output of your driving transceiver or transmitter using a 50 ohm
coaxial cable with an PL-259 male connector on the KPA500 end. The driving transmitter must supply
up to 40 watts for full output from the KPA500.

3. Attach the

RF OUTPUT {1}

to a suitable load with an SWR of less than 1.5:1. A dummy load is strongly

recommended for initial testing.

4.

Connect the PA KEY

{8} to the driving transmitter Key Output. This line must be grounded to transmit,

and 1 mA of current is sourced. The KPA500 PA KEY jack is pulled up to 5VDC when not
transmitting.

5. Optional: If the driving transceiver is an Elecraft K3, connect

K3 using the optional cable. This cable is not required to operate your KPA500. It allows full use of the
control functions on the K3. Note: This is not a common VGA computer cable.

6. Optional:

RS232 (PC)

connects the KPA500 to your personal computer with a standard 9-pin serial

cable. Required for updating the KPA500 firmware.

GND

thumbscrew {10}. A good station ground is important for

ON

switch, that indicates the

AUX1

{5} to the AUX connector on the

7. Optional:

RS232 (XVCR)

connects the KPA500 to a Kenwood transceiver using a standard 9-pin serial

cable.

8. Optional:

ALC OUT

{6} provides level information to control the driving transmitter RF level. The

output is negative-going from -4 VDC to -9VDC.

IMPORTANT: Position the amplifier so there is at least 2 inches (5 cm) clearance behind and
above the amplifier for proper air flow.

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