Hi Phil. Yes, I suspect its the padder. Carl & Rich have also suggested
its probably something in the output network. Time for some beefier
components. Since the problem manifests itself only on 160, I suspect
its the padder. I'll take the advice and parallel up something more suitable.
73 de Walt Kornienko - K2WK - zak@goes.com
-----Original Message-----
From: Phil Clements <philk5pc@connect.net>
To: Walter Kornienko <zak@goes.com>; amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
Date: Saturday, December 06, 1997 4:28 AM
Subject: Re: [AMPS] Decreasing power on 160
At 11:47 PM 12/5/97 -0500, you wrote:
>Hey all. Ran a bit of the 160 contest tonight and noticed that after
>about 45 minutes of heavy use power output started falling off on
>my homebrew 3 x 4-500 amp. The input SWR isn't changing but
>the output tuning seems to be effected. After 5 minutes cool off
>its back up to full legal output. Could the plate blocking caps, a
>pair of TV door knob types, be the culprit? Any ideas?
>
> 73 de Walt Kornienko - K2WK - zak@goes.com
More than likely Walt, it is the padder cap on your loading variable
cap. A small doorknob is not rated for the kind of current you are
putting through it. The Alpha 77SX has this same problem. Replacing
the padder cap. with two caps of 1/2 the original value in parallel
will solve the problem. If you have room, you can put in 4 caps of
1/4 the value taken out. GL! Also TV doorknobs are not RF rated but
don't let the word get out as a lot of us have been violating the
rules of nature for many years. If you operate a lot of 10-12-15
meters, I would install a glitch resister in the B+ lead as the
TV doorknobs will short sooner or later.
(((73)))
Phil, K5PC
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|