FW: [Elecraft] K3 and StepIR/Icom PW-1

[Adam Farson]

Hi Greg,

The PW1 uses the ALC loop as an essential part of its protective subsystem,
as described in the service manual excerpt  which I sent you. Any one of
several anomalous operating conditions (including over-drive and load
mismatch) will pull down the ALC line to reduce the drive. This is the
amplifier's first line of defence. 

I would never put an expensive piece of equipment such as the PW1 at risk by
connecting it to an exciter without a fully-functional ALC loop. 

Cheers for now, 73,
Adam VA7OJ/AB4OJ

-----Original Message-----
From: Greg - N4CC [mailto:n4cc at alltel.net]
Sent: 7-Sep-08 19:05
To: Adam Farson
Subject: Re: FW: [Elecraft] K3 and StepIR/Icom PW-1

I'm using the K3 with a PW-1 and the beauty of it is you don't need the ALC
if you use the K3's capacity to store the power level (drive
level) for each band.  Obviously if you use the K3 barefoot at 100 watts you
would have to be careful to turn it back down with the amp but I just leave
it at the saved settings that I have established for output for each band.
The proper drive level does vary somewhat by band.  You are right about the
ALC ..the K3 ALC is not compatible with the PW-1 and you should not connect
the ALC line between the two.  73 de Greg

At 09:08 PM 9/7/2008, you wrote:
>  Hi Tom,
>
>The K3 should not be used as an exciter for the PW1 unless the polarity 
>of its external ALC input has been changed from positive-going
>(original) to negative-going (range 0 to -4V). Failure to heed this 
>warning will result in extensive damage to the PW1, necessitating 
>costly repairs (as much as
>$1800!)
>
>http://www.ab4oj.com/icom/main.html#alc
>
>Cheers for now, 73,
>Adam VA7OJ/AB4OJ
>