>
>Thanks. ARRL handbook indicated that blocking capacitor voltage rating
>should be about 2x the plate supply, but I didn't know if commercial specs
>would agree.
>
// The maximum AC potential across a blocking capacitor is typically
less than a hundred volts at the lowest operating freq. The maximum DC
potential across one is the no-load anode supply voltage. The critical
rating is the RF ampere rating at the highest operating frequency. I see
no reason for the ARRL's statement. QST no longer has a Technical
Editor.
>It must have been about 4KV. I have to come up with a supply to power it
>with to check it out. I should be able to use the 3500V available in my
>AL-1200 to make sure all the amp's components are good before buying PS
>components to build a separate supply for it.
>
// I built a 8200v-no load FWD supply for the tetrode version of this
tube using a Peter W. Dahl 68-lb Hipersil transformer. It turned out to
be a case of too much. His next size smaller transformer would have
filled the bill. Gain was 18.2db with 140w drive.
cheers, Jerry
>
>At 07:10 AM 11/15/2001 -0800, 2 wrote:
>
>
>
>> >
>> >In an old 5CX3000A 1.6-32MHz amp I am working on, the plate blocking caps
>> >are rated at 8KV. Can I guesstimate from this what plate voltage was
>> >intended?
>>
>>// Eimac rates the 5cx5000A at 7kV in 24/7 AØ or FM. 8kV in SSB
>>service should be ok. The rated scrren potential is 1000v max. To
>>utilize the 5cx5000A's c. 6.5A-pk emissive ability, anode and screen
>>potential should be maximal. The 8kVDC blocker-C rating sounds adequate.
>> 5kVDC vacuum caps are ok with up to c. 3000v-pk at 32MHZ. This suggests
>>that the TMC anode-PS was roughly 4000v. For SSB use, I would consider
>>removing the resonant filter -choke, converting to a C-filter, raising
>>the screen potential. P-out should then be about one standard 6db S-unit
>>better than a SB-220. To run it at c. 1500w, tune it up at full
>>throttle - then back down the mic. gain until the anode-I barely wiggles.
>> Increase mic. gain as needed to maintain communications.
>>
>> >It was made by TMC, presumably to commercial or military specs.
>> >
>> >If it helps, it has vacuum variable caps in the tank rated at 5KV.
>> >
>>cheers, Jerry
>>
>>- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
>>end
>>
>>
>>--
>
>
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>
>
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
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