[Amps] 500 uh plate choke

Rob Atkinson ranchorobbo at gmail.com
Tue Jan 22 18:30:04 EST 2013

you can test your chokes yourself.  Get a modern solid state ham rig
and fix it so it puts out around 20 watts cw.  dump the RF into a 50
ohm resistor and put a T in the line.  Connect the stem of the T to
the choke; the cold end of the choke connect to a 5 or 10 watt
incandescent lamp shunted to the feed shield.  if you have a scope put
it in the line with the lamp using a feedline probe.  Spin the VFO on
the rig across all the bands and see if you see the lamp light or any
RF on the scope trace.

Calling it a pi choke and not a pie is what I get for trusting Google.
 I thought it was pie because of the pies but there were so many
google hits where it is called pi that I thought I was mistaken.



On Tue, Jan 22, 2013 at 3:16 PM, Vic K2VCO <k2vco.vic at gmail.com> wrote:
> I have several large pie-wound chokes, most around 1 mh or more. The thing
> about this one is that they found no series resonances below 100 mHz. It
> seemed to me that 500 uh would work well on 160m.
> I have used the RFP chokes, which I think are about 225 uh. This is about
> 2500 ohms reactance at 1.8 mHz, which most likely makes the choke part of
> the tank circuit. My feeling is that this detracts from efficiency on 160,
> because the choke is a low-Q device.
> On 1/22/2013 12:59 PM, Carl wrote:
>> Pi stands for pie Rob, resembles a pie plate.
>> In the "old days" the RF tanks were series fed so there was no concern
>> about resonances and a lot of inductance was used.
>> Carl
>> KM1H

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