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[AMPS] SB-220 input circuit

To: <amps@contesting.com>
Subject: [AMPS] SB-220 input circuit
From: measures@vc.net (Rich Measures)
Date: Wed, 4 Aug 1999 04:52:28 -0700


>
>Pete Smith wrote:
>> >Replace C-32.  
>> /// snip//
>> The coupling capacitor from the input circuit to the cathodes?  Well, it
>> sure would be easier than dismantling the input circuit.  Have you
>> personally seen this particular failure?
>> 
>> 73, Pete Smith N4ZR
>> n4zr@contesting.com
>-----------
>Hi Pete,
>I have seen it 3 or 4 times.  The first time was in 1977 shortly after I
>started work as the ham radio tech at the Heathkit store here in Dallas.

?  What was the failure mode for the kaput cathode coupling capacitors?  

>The amp was a "warrenty" return and I spent entirely too much time
>trying to find the problem...Benton Harbor was no help.  I finally
>mentioned it on one of the local repeaters and someone broke in and told
>me exactly which part to replace.  The owner got his amp back the next
>morning and I sent a note to Benton Harbor about it...dont know if it
>ever got published as a "tech note"as I was not at Heathkit very long
>before going to IcomEast.
>Since then, I've seen it in 2 or 3 other amps including the one Ive been
>using for the last 20 years. I hope the cap is the problem in your amp
>as its a 15 minute job to replace it and several hours to get to the
>input circuitry.

?  Accessing the tuned inputs requires removing the front panel.   For a 
SB-220 this should take no more than ten minutes.  

-  cheers, Bob


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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