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

[Adam Farson]

Hi Greg,

Still, I would feel a lot more comfortable were Elecraft to correct the
polarity of their external ALC input to the negative-going industry
standard. I understand that this modification is presently underway. 

Given the growing popularity of solid-state amplifiers (which all provide
negative-going ALC voltage, to my knowledge) I can think of no rational
reason for not making this change.

Cheers for now, 73,
Adam VA7OJ/AB4OJ


-----Original Message-----
From: Greg - N4CC [mailto:n4cc at alltel.net] 
Sent: 7-Sep-08 21:00
To: Adam Farson
Cc: elecraft at mailman.qth.net
Subject: Re: FW: [Elecraft] K3 and StepIR/Icom PW-1

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: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
> >
>