[Amps] 87 a query re align motors?

[Gary E. Jones]

Charles:

Since you didn't mention any of this in your post, I assume that it did not
happen, but just in case, let me share a similar experience. 

I had to return my amp (87A) to Alpha to replace pin diodes, which gave out
after about 12 years of use. When I got the amp back "fixed", the factory
had done something that cleared all the segment tuning on 4 or 5 of the
bands, meaning that although it worked fine on all bands before, three or
four of the bands were badly out of tune when I got the amp back. It would
kick to error on those bands regardless of how much power I was putting into
the amp (even a few watts immediately kicked the amp into fail mode). What I
had to do was manually re-program those bands by hand, because as I said, I
would kick the amp into fault mode even with 5 or 10 watts of drive. 

So I had to tune everything into a dummy load at 50 ohms, and even sometimes
try various segments within a band at the lowest drive I could get out of
the transmitter before I could find a sweet spot to begin the tuning of that
band, and finally with much playing around, I could get a band to come back
into reasonable tune. I literally had to manually tune and save each band
segment back into the computer memory. The manual tune and save process are
described in the manual. 

It took a lot of work, but now I have it working on all bands 160 to 10. RF
Concepts and Molly were very helpful in giving me some advice on this but
never gave me a clear idea of what happened at the factory because there are
supposed to be stored factory defaults for each band that you can retrieve
easily following the procedure. But my guess is that these defaults got
erased while on the bench and the amp got totally out of tune, and I had to
find the correct settings from scratch. I bought a good dummy load that
could take a reasonable amount of 1500 watts and worked on it slowly over
several days, and got my problem under control. 

       Hope any of that helps....

                     Gary      W5FI 






-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Charles Harpole
Sent: Friday, March 25, 2011 1:29 AM
To: amps at contesting.com
Subject: [Amps] 87 a query re align motors?


I need advice re the Alpha 87a .... all the auto tuning via AlphaMax or by
hand run the motors/caps all the way to one end or the other and give me a
not-so-good load with the TUNE indicator 7 to 9 LED bars to the RIGHT of
center.  Either this is a bad SWR load (shows ok on other rigs/tests) or
maybe the tuning stepper motors and caps are misaligned.
 
Anyone have advice about problem or a fix??????????
73,

Charles Harpole k4vud at hotmail.com 
 		 	   		  
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