[AMRadio] Re: Transmitting Mica F2 -vs- G2 types


D. Chester k4kyv at charter.net
Wed Sep 19 00:48:19 EDT 2007


On 9/13/07, A.R.S. - WA5AM <ars.w5ami at gmail.com> wrote:
> I am getting ready to convert my Gates BC-1T to 75 and 160 and need
> some opinions on the loading cap.  The 1T uses fixed capacitance and a
> variable inductor for loading.  I need about 750 pF for the loading
> cap on 75 meters.  The original loading caps (two in parallel) are G2
> micas at 8000 vdc, however they are both 1500 pF.  I have a type F2B
> that is 800 pF at 6000 vdc, that would be close enough, but I'm afraid
> it may not handle the current.  The F2 is a much smaller unit than the
> G2's that are in there now.  Anyone have any opinions on what the F2
> can handle?  Being on a higher freq. than original design I think the
> 6KV rating might be okay, but I'm still concerned with the current
> rating of the F2 as opposed to the type G2.

Brian,

You don't need another loading cap.  Just rewire the two existing 1500 pF 
caps in series instead of parallel.  That will give you 750 pF @ 16000 vdc.

In mine, I ended up using two identical caps in series to arrive at the 
value I needed for the main plate tuning capacitor.

Don k4kyv 



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