[Amps] Power output drop

[Carl]

Tank circuit cap drifting should be mitigated by retuning and going open is 
very uncommon in US made caps.
More likely a coupling cap, plate coke or its bypass.

A .0047 is sufficient as coupling at 160 and should be made of 2-4 decent 
size ceramic caps that can handle the current. WW2 micas are prone to 
leakage and RF heating.
And the plate choke looks like it got rather hot in the center. The 
Ameritron is a good replacement at $20.

There is too much variation in the photos to figure out what caps are used 
and where/when.

Carl
KM1H


----- Original Message ----- 
From: "Vic K2VCO" <k2vco.vic at gmail.com>
To: <amps at contesting.com>; <mikewate at gmail.com>
Sent: Tuesday, September 10, 2013 9:29 PM
Subject: Re: [Amps] Power output drop


> Does the line voltage droop when you transmit, causing a drop in filament 
> voltage?
>
> Do you have ceramic capacitors in the tank circuit that heat up and detune 
> the tank?
>
> On 9/10/2013 6:03 PM, Mike Waters wrote:
>> `
>> Anyone have an idea why the power output of my dual parallel 833C 160m 
>> amp
>> often drops 200+ watts after several seconds? Re-tuning does not bring it
>> back up to the initial output.
>>
>> Not that a drop from 1500 to 1300 watts is a big deal, but inquiring 
>> minds
>> want to know the reason. :-)
>>
>> Description:
>> www.w0btu.com/833C_linear_amplifier.html
>>
>> More photos:
>> w0btu.com/files/misc/833C_linear_amplifier/?C=M;O=D
>>
>> 73, Mike
>> www.w0btu.com
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>
> -- 
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
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