[amsat-bb] Solid State conversion (tube equivalents)?

Robert Bruninga bruninga at usna.edu
Sat Feb 25 21:07:53 UTC 2017

About 40 years ago, the topic of tube-to-FET conversions was popular for
making 1-for-1 conversions of old tube stuff to solid state.

Anyone feel good at doing this these days?  Or am I just wallowing in

Today at a small hamfest, (40 tables only) there were at least 4 of the old
high quality FREQ meters (9" cube boxes) that could give frequency accuracy
to 0.01% anywhere from 125 KHz to 20 MHz.

Going rate was about $10.  What an absolutely astonishing piece of 1930
engineering when you open it up. , with 3 tubes. (6A7, 76 and a 77)

I can do just about anything with bi-polar transistors... (my coming of
age...) but I PRE-dated FET's which are good direct substitutes for tubes
since they are both transconductance devices .

There is an excellent 1969 QST article on doing tube conversions, but it
assumes one already knows more about it than I do.  And one of the tubes is
a penta-grid tube which does oscillator and mixer all in one...

I would have thought that a solid state conversion of this simple 3 tube
but very useful device would be out there somewhere...  But haven't even
found a schematic on line...

Thought I'd ask before all the old fuds are gone...

Bob, Wb4APR

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