Care and Feeding an Icom PW1
W6DE
Page 1
Copyright 2017, All rights reserved.
Care and Feeding of Icom PW1 1,000 Watt Solid State Power Amplifiers
W6DE, November 2017
Use the following information at your own risk. No warranty is offered, implied
or expressed. I make no warranty as to correctness or completeness of the
following information. I am not associated with Icom, nor has the information
contained herein been approved by Icom. Modifying, repairing and/or
following these procedures may void Icom’s original Manufacturer’s warranty.
If you undertake any repairs and/or adjustments to your PW1 amplifier based
on this information you do so at your own risk.
This is a compilation of replies I have made to the Yahoo! PW1 on-line forum. This is loosely organized
around the causes of why PW1s fail, how to protect PW1s and how to repair some PW1 failures.
Setting up a PW1 with an Icom Radio:
Some folks find the ALC Level adjustment confusing. I drive my PW1 with an Icom 7600 radio which I’ll
refer to as exciter and/or radio. I adjust my ALC level on 20 or 40 meters. I use the Icom supplied cable
to connect the radio ACC2 connector to the PW1 ACC1 connector. The Icom supplied cable routes the
ALC and PTT signals between the radio and amplifier.
The following advice about setting the ALC level is not the Icom recommended method. While I believe
this is a safer method to adjust the PW1 ALC, you follow this advice at your own risk. Here is how I
adjust the ALC:
--#1 rule: Never use the radio/exciter’s antenna tuner when operating into a PW1!
--#2 rule: Everybody should have a dummy load. If you don’t have one, borrow or buy one—tuning and
adjusting into an antenna is just looking for trouble. A good dummy load is always on the right
frequency and always has low SWR.
For the following steps do not engage the PW1’s “TUNER” you should be operating into a matched load
of 1:1 SWR!
--PW1 should be connected to the mains power. The PW1 power can be on, but the “TUNER” and
“AMP/PROTECT” LEDs should be off. That is; the amp should not be amplifying and is in “by-pass”
mode.
--When setting ALC, set the PW1 meters to read PO (on the left meter), and ALC (on the right meter).
--Set your radio’s meter on Power Out. Set your exciter power out to its lowest position. Set your
exciter to CW mode and use a hand key to transmit; a second way to generate the correct amount of RF
is to select FM and the press TRANSMIT key on the radio front panel. DO NOT use or connect the hand
mic to the radio, the mic may pick up sounds and effect the readings.
--In contrast to Icom directions: start setting ALC with lowest exciter power and then slowly turn up the
exciter’s drive.
--When you get to around 100 Watts out of the exciter (remember the amp is off), Stop raising the
exciter’s power, stop transmitting.
