[Amps] Plate Voltage Not Stable

[Carl]

I might add that Dentrons are notorious for bad caps blowing transformers. 
Part of it is due to using only a 500pf plate choke bypass and operating a 
lot on 80/160. Electrolytics do not like RF.

That meter indication is a classic for both diodes starting to break down 
and caps ready to short.
Be very quick with the retest.

The comment about meter multiplier resistors are valid BUT in that amp they 
used 1% precision HV resistors. OTOH the equalizing caps across each cap are 
garden variety carbon composition and one breaking down or way high in value 
could hasten a cap failure.
Removing the lead from the HV board to plate choke will eliminate that path.

Carl
KM1H


----- Original Message ----- 
From: "Carl" <km1h at jeremy.mv.com>
To: "Ken Durand" <N4zed at comcast.net>; <amps at contesting.com>
Sent: Saturday, February 15, 2014 6:19 PM
Subject: Re: [Amps] Plate Voltage Not Stable


> If they are the originals they are long overdue. Pull the tubes first and 
> retest BUT still replace the caps in any case.
>
> I believe FAR Circuits has a new PC board that is for the modern Snap-In 
> caps.
>
> Carl
> KM1H
>
>
> ----- Original Message ----- 
> From: "Ken Durand" <N4zed at comcast.net>
> To: <amps at contesting.com>
> Sent: Saturday, February 15, 2014 5:45 PM
> Subject: [Amps] Plate Voltage Not Stable
>
>
>> The plate voltage on my MLA-2500 amp has always been rock steady. It has 
>> a
>> dedicated 220v line ran to it. The plate voltage has always been 2400v as
>> read on the panel meter....
>> After powering on the amp the other day this is what I get...Time to 
>> replace
>> the caps and rectifier diodes? They are original.
>>
>> https://www.dropbox.com/sc/uvd3jcwbrk86226/lDmNszwxYP
>>
>> Ken
>> N4zed
>>
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2014.0.4335 / Virus Database: 3705/7095 - Release Date: 02/15/14
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2014.0.4335 / Virus Database: 3705/7095 - Release Date: 02/15/14
>>
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2014.0.4259 / Virus Database: 3705/7096 - Release Date: 02/15/14
>>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2014.0.4259 / Virus Database: 3705/7096 - Release Date: 02/15/14
>