You would only bypass at the B+ end, you want this choke to think it is 1
choke... The center bypassing would make it act as two chokes.
It would be better to wind a single choke bigger in diameter than putting
the chokes at right angles if you are doing that to fit in the box. You
want the unit to act as 1 choke - 1 inductance.
Here's a method I invented but never published until now.
I used a vacuum relay (single pole single throw or RJ-1 in a pinch) at the
center of the two 90uH chokes to connect to a 1000pF cap to ground. When
the relay was open you were on 160 meters, when the relay was closed the
choke connected to the grounded 1000pF capacitor. Even though the two
chokes were still in series the first and second chokes by being bypassed in
the center made the plate end choke the active unit.
This kept series resonances from destroying the larger choke on 80-10
meters. Some commercial amps do this by a creative single piece chokes that
are groups of smaller chokes on one core. This is an attempt to break up
the series resonances. You start winding and sweeping the choke across the
spectrum looking for series resonances.
Once Henry started building 160 meter amplifiers, they physically shorted
across a chunk of the plate choke (no cap) this works too but I liked my
method better. Maybe because it was my method?
BOB DD
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of kenw2dtc
Sent: Wednesday, January 24, 2007 4:59 AM
To: amps@contesting.com
Subject: [Amps] plate choke bypass caps
I'm building a 160 meter linear. I plan on using two 90 uhy chokes in
series and at right angles to one another. Do I put the bypass cap just at
the B+ point or should I also bypass in the center of the two chokes?
73,
Ken W2DTC
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