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Re: [Amps] AL-572 high input SWR

To: amps@contesting.com
Subject: Re: [Amps] AL-572 high input SWR
From: K4RO Kirk Pickering <k4ro@k4ro.net>
Date: Wed, 29 Dec 2004 09:40:28 -0600
List-post: <mailto:amps@contesting.com>
<following up from a question I posted a year ago...>

The amp has been fixed by replacing all four tubes.
It seems to work fine now, with full output and
reasonable looking input SWR.

Can someone tell me how to perform the 10-meter mod?
I don't have a FAX, and I would rather not wait for 
snail mail to Starkville if possible to get the info.

Finally, any suggestions on replacement pilot lamps
for the AL-572?

Thanks again and 73,

-Kirk  K4RO


On Sun, May 09, 2004 at 08:46:20AM -0500, K4RO Kirk Pickering wrote:
> A friend has asked me to look at his Ameritron AL-572.
> The amp quit functioning about 7 months ago, after two
> years of dependable service.  The amplifier was used
> almost exclusively on 17 meter SSB. The symptoms are 
> as follows:
> 
> Very low output - 100W on 20m-10m, 300W max on 160m-40m
> 
> Very high input SWR - > 3:1 on all bands, over 5:1 on 17 
> meters. This is the SWR the radio "sees" looking into
> the input of the amplifier.
> 
> My first guess was that a component (which is common to 
> all bands) on the tuned input  circuit has smoked. A 
> quick visual inspection does not reveal any burned parts.
> 
> Before I go digging deeper, does anybody have any
> experience with this amp or suggestions on what may
> have failed?  Thanks for any assistance.
> 
> -Kirk  K4RO
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