[Amps] Alpha 76a

[Carl]

I dont trust any electrolytic that is 30 or so years old. At $13 and change 
each I bought new ones from Ameritron and also replaced the equalizers.

A big problem with many 76's is the C-109 tantalum, C-108 electrolytic, 
R-116 (go to a 1W), and R-124 a 2W carbon that drifts up in value to the 
point K-6 never activates.

Carl
KM1H




----- Original Message ----- 
From: "Colin Lamb" <k7fm at teleport.com>
To: <amps at contesting.com>
Sent: Monday, September 12, 2011 4:43 PM
Subject: Re: [Amps] Alpha 76a


> "One thing you might consider if you haven't already is replacing the 
> power supply HV filter caps.  They are more than ready One thing you might 
> consider if you haven't already is replacing the power supply HV filter 
> caps."
>
> Two weeks ago, I had my Alpha 76A apart and decided to check out the 
> electrolytics and bleeder resistors.  I removed each capacitor and checked 
> them with a capacitance meter and and ESR meter.  I also measured the 
> leakage current under load.  The amp had not been used for years, but 
> after forming for a few minutes, the leakage current dropped to almost 
> nothing.  Measured capacitance was within a couple percent.
>
> These caps are high quality original caps and did not need replacement. 
> Although I have found other amps that needed replacement caps, the Alphas 
> have held up well.  Worthwhile to try them before replacement.
>
> 73,  Colin  K7FM
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