[ARC5] [Milsurplus] 6AQ5 Tank

[J. Forster]

> Ok all you smart people-
> I'm looking at a 6AQ5 Pierce crystal oscillator/tripler
> with a plate tank circuit which outputs at 24 MC.
> The plate tank capacitor is 40 pFd.
> The capacitive reactance at 24 MC is only 166 ohms.

You have to multiply by the Q. If the Q=100, it will look like 16.6K

> This seems low for a tube tank.  Output capac.
> of 6AQ5  is 6 pFd,  so that doesn't change the picture much.

Agreed.

> I was looking at changing the tank to output at 3.9 MC,
> but if Xc = 166 ohms is correct, the tank cap
> at 3.9 MC would be 6.7 uFd.  That can't be right.

Let's see:

The frequency scales as the SQ. RT. of LC

24 MHz / 3.9 MHz = about 6, so the C needs to be 6*6 *40 pF = 6*240 = 1440
pF.

This is probably still too large. I'd increase the number of turns on the
coil by about 6 and the C to about 240 pF.

Best,

-John

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