Date: Tue, 07 Jun 2022 18:43:13 -0500
From: donroden@hiwaay.net
To: Amps Amps <amps@contesting.com>
Subject: Re: [Amps] Blowing out finals on a Icom 7300 using a
Ameritron AL80B. Help Please!
<how bout an RF Choke .... internal or external to the input to the amp ?
< W4DNR
## On paper, that should work. Wired between one cathode lug..and
chassis.
I would be real careful using those small pi wound chokes, like typ used
across a load cap. Ever had a plate block cap short ? The pi safety choke
explodes.
## what works better is a torroid, wound with 12-18 ga magnet wire.
50-100 uh is ample, with no series resonances between 160-10m. This works
good across a load cap. It would/should also work between cathode to
chassis But it would also be effectively in parallel with the bifilar fil
choke too. GDT's would be a cheap and effective method.
## too bad the chinese don't know how to build a tube. perhaps what's
needed, is to hi pot test between anode and cathode. It should be sky
high. A good 3-500Z should hi-pot test to 15-16 kv, between anode to
grid. And several kv from grid to cathode.
Jim VE7RF
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