[Amps] Series C in amp output

[Vic Rosenthal]

I have always thought those ‘safety’ chokes aren’t worth much. The 2.5 mh chokes often used in that spot are rated at 300 or even 125 ma, and I suspect they would open long before the plate supply fuses would blow.
But note that the capacitors Martin mentioned are only rated at 500v, so they aren’t much of a safety feature either!

Vic 4X6GP 

> On 9 Feb 2018, at 18:58, Bill Turner <dezrat at outlook.com> wrote:
> 
> ------------ ORIGINAL MESSAGE ------------(may be snipped)
> 
>> On Fri, 9 Feb 2018 17:06:25 +0700, you wrote:
>> 
>> Amps from Acom and OM, maybe some others, have a large amount of 
>> capacitance in series with the output after the power/SWR bridge. In the 
>> case of the Acom 1000 this is 6 parallel 10nF/500v disc ceramic 
>> capacitors with a 1 megohm (static bleed?) across them.
>> 
>> Have not seen this configuration on older Alpha amps or others. Can 
>> anyone comment on the purpose?
>> 
>> Thanks
>> 
>> Martin, HS0ZED
> REPLY:
> 
> Just a guess:  It might be a safety issue. In case the plate blocking
> capacitor shorts, it would prevent HV from appearing on the antenna.
> Other amps do this protection with a RF choke across the output of the
> Pi network. In case of a blocking cap short, the fuse(s) would blow.
> 
> 73, Bill W6WRT
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