Capacitor values

[rftb_cowboy]

Looking at available schematics they all show the three variable capacitor to be 100 micro micro farads. Are they 100 micro farads? Or is the double micro a reference to something else?

Matt

[Parasetguy]

Hi Matt

Micro Micro = pico
(10 to power 6 plus 10 to power 6 = 10 to power 12)

Regards,
Henk - Parasetguy

[rftb_cowboy]

Yes I was aware of that but why was it not simply printed as pF on the schematic? Am I missing something?

[Parasetguy]

They just did not do that, back then. This indication was also used on capacitors.

[rftb_cowboy]

Got it. Thanks

[rftb_cowboy]

So I pulled some tuning capacitors from some old 40's radios.
They are 200 and 400 pF. I am looking at adding 200pF in series to make the range 30-100pF.
Any issue with this approach?

[Parasetguy]

Only read it today.
So you want to put a 200 pF cap in series with a 200 pF variable cap.
That will work, only the characteristic of the tuning will be a bit "odd".
Throw in the values here:
https://www.digikey.com/en/resources/co ... -capacitor
and see what happens if your var cap is at 0 , 25%, 50%, 75% and 100%.

73 de Henk - Parasetguy