[Amps] Vacuum or Air?

[Vic Rosenthal]

StephenTetorka at cs.com wrote:

> Permit me to pose one: what factors (other than cost) should be considered in
> choosing between a vacuum variable and an air variable capacitor?

Advantages of vacuum variables:

1) Lower minimum capacity for a given maximum capacity.  As a result, you can
have an efficient amp on 10 meters without needing to switch in padders on LF bands.

2) Higher voltage rating for a given physical size.

3) Lower parasitic inductance.

Advantage of air variable:

1) 180 degree rotation -- no cranking when changing bands.

I have built amplifiers with both.  I change bands a lot and prefer air
variables.  Of course, if you implement a motor drive with presets, then you can
have the best of both worlds.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco