Eico 324 inductors

[alfa88]

I'm restoring an EICO 324 Sig Gen and while I find the documentation is readily available a closer look reveals that the actual inductor values are missing and simply referred to as coil "A" through coil "E". Not that I need to change them but it would be nice to know.

 

[shrtrnd]

Holy cripes. Variable Inductors that need to be tweaked for calibration.
If the manufacturer doesn't list the values, (and I found the need to know), I would probably
pull each one and put it on a Sencore Z-Meter to find the values.
Somebody here might have another idea, but that's mine.

 

[bertus]

Hello,

I have found these at JABSE.
eico_model_324_rf_signal_generator.pdf
eico_model_324_rf_signal_generator_1954.pdf
eico_model_324_rf_signal_generator_construction.pdf

Bertus

 

[alfa88]

I had another thought but pretty much ran into a dead end. The circuit uses a tank circuit via a variable air capacitor. If I have the low and high values of said part I just do a lot of calculations. I don't have a cap tester with me but maybe someone out there has some insight.

 

[bertus]

Hello,

Have a look at this page:
http://www.peeblesoriginals.com/catalog/15.php

The number of plates determines the capacitance.

Bertus

 

[PETERDECO]

Yes if you knew the low and high value of the variable capacitor, you can determine the inductance. I have a chart that lists frequency and L and C impedances. A long time ago I saw a parallel tank circuit that used a 5-30pF variable but no value for the inductor. At 30pF it resonated at 70MHZ, at 5pF it resonated at 130MHZ. Using a ruler I "connected the dots" to determine it was a something like a .1uH inductor.