Subject: Re: [AMPS] Choke series resonance clarification
> What I generally do is close-wind the choke and mount it in the
> final location, then check for resonances. If I find something in or
> near a Ham band I use a metal wand moved along near the choke
> to find the hot spot that moves the resonance the most. Then I
> remove turns at that spot to move the resonance above the Ham
> band a safe amount.
Creative Electronics uses a very "creative" approach to choke design
that works 99% of the time without measuring and pruning.
A 38 uh choke is installed in series with a 180 uh choke; the 180 uh
choke being on the power supply end of the HV circuit. A pair of
4700 pf @ 10 kv capacitors in parallel are installed at the junction
of the two chokes. The cold ends of the caps are pulled to ground
by a common open frame relay on 40-10 meters, and left floating
on 160 and 80 meters. Another
pair of
4700pf 10 kv caps are hard-wired at the base of the first (180 uh)
choke. This works well with their CE-2500A (3CX3000A7) and
other amps they build.
I have used this scheme several times...the chokes run cool and
do the intended job very well.
(((73)))
Phil, K5PC
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