I once blew up an unprotected amplifier's output circuit when a flaky
antenna feed line opened with 1500 watts RTTY applied. Prior to
that, I didn't think I needed anything more than a hand on the drive
level control to keep my amp safe.
Now I make sure the ALC is there so the amp can cut that drive within
milliseconds if the antenna opens up again.
The K3 ALC fix is available from Elecraft. It works.
Jerry W4UK
At 12:00 AM 9/8/2008, Greg - N4CC wrote:
Adam -- I guess it depends on the user. Certainly having the ALC
connected (if it were compatible) would be preferred...but my point
is that saying " the K3 should not be used as an exciter for the
PW-1" [without ALC] is not entirely accurate. it is possible to use
the PW-1 without ALC. It can be done and done quite
safely. Granted you lose a measure of protection but if you use the
K3 as I do -- where it recalls the drive setting by band, a unique
feature of the K3 -- it is less likely that not having the ALC
connected will ever be an issue. If you change the power settings
frequently and are not careful to return them to the desired drive
level when operating the amplifier then your chance of damaging the
amp increases without the ALC. Cheers. 73 de Greg
At 10:53 PM 9/7/2008, you wrote:
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:[EMAIL PROTECTED]
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
>
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