R: [AMPS] Plate Choke Inductance

Maurizio Panicara i4jmy@iol.it
Mon, 17 Apr 2000 18:07:21 +0200

In term of stability for higher bands and a single choke used, the minimal
possible inductance on the lowest frequency that doesn't substantially
modify the plate impedance (and having the first self resonance above 32-35
Mhz) is the correct one.
My practical method is to check the matching network return loss, from the
50 Ohm side, with and without the choke connected to it. (RL has to be
simulated with a non inductive resistor temporary installed)
If frequency dips and curves depth doesn't change much, then the choke
reactance is good at a stated frequency.
Using a spectrum analyzer and a tracking generator the above method is easy
, quick and prooved good.
Tuning to each band with the same setup and connecting/disconnecting the
choke from the rest of the circuit it's also possible to display for
parasitic resonances before applying power.

Mauri I4JMY

----- Original Message -----
From: <Wt8r@aol.com>
To: <amps@contesting.com>
Sent: Monday, April 17, 2000 5:28 AM
Subject: [AMPS] Plate Choke Inductance

> What rule of thumb should be followed when dimensioning the inductive
> reactance of a plate RF choke, i.e., with respect to the plate impedance?
> Should it be at least equal or ?????
> What recommendations do you have for me and how is that determined?  Seems
> remember reading something about the amount of current being shunted to
> ground at the high voltage input end of the choke by the bypass capacitor.
> Thank you.
> Dave, WT8R

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