Date: Thu, 4 Jan 2018 18:38:47 -0500
From: AJ <iamfromcanadaalso@gmail.com>
To: amps@contesting.com
Subject: Re: [Amps] Plate Choke Issue
<Interesting that Henry had a 20 uh choke for 20,15,10. That seems to be
<where it blew apart.
> ## His larger choke really requires 2-3 x 4700 pf ceramic bypass
> caps. His smaller choke should have its uh increased to 50 uh. The
> smaller choke should ideally use 1-2 x 500 pf doorknob style
> bypass caps, like a HT-50 or HT-58 series, which are available in 5
> kv..and also 7.5 kv.
<This would require me to add another relay at the feed point if I
<understand you correctly.
<A flash over to the chassis through the ceramic insulator to the ss
<bolt is possible, it was excessively long and reused. I have ordered
<some ceramic bolts to eliminate that possibility.
<Sincerely AJ___ VE3HJ
## The henry radio setup was a dogs breakfast. They originally used
3 x 150 ohms, at 5 watts each, resistors in parallel + a few turns of
strap..for the parasitic
suppressor. Later versions used just a single 1 inch wide, and thick, chrome
plated strap
coil for the suppressor. Last version had no suppressor at all. The 3x3 tube
does not require a
suppressor ! Their 2 x piece plate choke setup was changed a few times. The
20 uh coil
was wound with 18 ga wire. The 180 uh coil was wound with, I think, 24 gauge
wire.
## No 2nd relay required with the 2 chokes, when using different values of
bypass caps.
The 500 pf ones are a better bypass on the upper bands. The 4700 pf disc
ceramic types,
are a better bypass on the lower bands. Any residual RF that gets past the
respective plate
choke being used at the time, will route to the respective bypass cap that
functions better.
## The 8 K ultra used 3 x 4700 pf caps + 2 x 500 pf doorknobs, all in
parallel, at the base of the
larger 180 uh choke. 20 uh choke was in series, and at right angles to the
large choke. Base of small
choke was mounted to top of big choke, via an aluminum L bracket. A modified
HV solenoid was used
to short out the larger choke, when amp used on 20-10m.
## The bypass capS at the base of the plate chokeS is not a critical issue.
Your 5000 pf is probably ample.
## Either use a shorter SS bolt for mounting the chokeS, or better yet, ur idea
of using ceramic bolts.
Jim VE7RF
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