[Boatanchors] Japanese WW II Code practice oscillators

[J. Forster]

Most likely to adjust the frequency of the CW note. Since the impedances could
be pretty high, an ordinary capacitor of a few hundred pf could well tune in the
audio band.

Years ago, I had an Eico audio signal generator that went from roughly 20 Hz to
20 KHz with a 365 pf tuning cap, from what I remember after 40+ years.

FWIW,
-John

William L Howard wrote:

> I have been discussing Japanese WW II code practice oscillators with the
> seller of the set now up for sale. The Japanese Navy Code practice
> oscillator runs from either AC or DC, has two tubes, one a rectifier
> tube and the other I assume is an oscillator. The Army version is
> battery powered, has one tube and a variable capacitor. The question was
> "Why have a variable capacitor in code oscillator?"
>
> Now remember this is 1920s state of the art so can anyone make a
> suggestion as to why the variable capacitor?
> Pictures of both sets can be found on my web site article on Japanese
> radios.
>
> Thanks,
>
> Bill Howard
> William L. Howard Ordnance Technical Intelligence Museum
> wlhoward at verizon.net  Web Site www.wlhoward.com Phone: 727-585-7756