[Hallicrafters] Wanted: education

[rdhalste]

Hi,

Calculate out the impedances for the 22 uh choke and then for the 2.5 mh
choke for the operating ranges.
You should find the first to have a relatively low impedance which will pass
those frequencies.

The second should have a very high impedance.
It's use across the output connector is as a safety device.  IF the plate
coupling caps short it would put the plate voltage on the coax center
conductor, except the choke will short it to ground while at RF it's an open
circuit.

Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair? (S# CD-2)
www.rogerhalstead.com


> Hi all;
>
> In working with RF chokes I noticed in several ARRL handbooks the
> circuits for amplifiers frequently use an inductance of 22 uh for the
> input choke; grid to ground for grounded cathode, or filament to (RF)
> ground for grounded grid amplifiers. However the same circuit uses 1 to
> 2.5 mh choke across the antenna connector. Why such a large difference in
> inductance when the frequency is the same (3-30) mc? An explanation would
> be appreciated. Thanks.
>
> Ed Richards K6UUZ
>
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