[Amps] QRO ?

[Will Matney]

Rich,

The problem is that running the tube at a lower voltage raises current for the same amount of power. Plus at too low of a voltage, it will not work. HV is not that bad as long as you observe the proper safety precautions. If your building an amp off of a proven design, it will work correctly. They do make HV air variable capacitors too for say 3000 VDC, but they are pretty large. For one with any capacitance, they'll be really long. Price wise, you can get either cheaper by buying off ebay or surplus houses.

Best,

Will


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On 8/4/05 at 10:17 PM Rich wrote:

>I am thinking about building my first amp and was wondering if I could
>use a large tube ( 4-1000a ) at reduced voltage when I first start out
>and then as I build confidence replace the lesser parts with better (HV)
>parts. I don't like the idea of buying vacuum variable caps and not
>being sure that the amp will work right. I am not looking for great
>efficiency at low voltage but only to prove the concept and all
>supporting parts like soft starts and delays and antenna relays work
>correctly before I go to QRO. Due to band conditions for the next few
>years it will be a mono-bander for 40m to start, 20m and 15m to be added
>later.
> I have smaller tubes I could start with like C1583A's, and 304t's.
> 
>Rich, KD0ZZ
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