From: [email protected] <[email protected]> on behalf of Brandon DX via groups.io <rfburnz@...>
Sent: Wednesday, February 14, 2024 6:40 PM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Loaded Plate chokes...again

I've been in and out and read this thread with some interest.?
My bets are the ferrite loaded chokes will ultimately fail in service (ie. 4CX15,000, 3CX10,000 and similar)
I guess the mention of ole Rich Measures makes me wanna pipe in on this subject, the nutcase that he was... (another story for another day)
anyhow I made plate chokes several years ago after one of the "commercial" hammyfied ferrite loaded chokes blew up and melted down.
Did some experiments using none other than a grid dip meter and buying Teflon by the yard.?
Does the source of Teflon matter? Yes absolutely Industrial grade. Unspecified Teflon can be (is) lossy.?
Does the type of wire matter, yes. Formvar please.
Does the type of Formvar matter yes if you want repeatability.? it comes in different temperature ratings.
I rebuilt most of (the critical parts) of W6CCP's Henry amplifier.? 3CX3000A7 P.O.C.
Attached is a pic of the second choke I had to add to make it perfect, note the small vac relay.
If I had access to a lathe again I would make a few of these.
but they wouldn't be FS to CB'ers. my notes tell why
Very 73,? ?Reid? W6MTF??
from my notes,? ?Series resonances: major at 26.95 minor at 17.2MHz
One series at 34.5MHz. Parallel resonance at 29.0 +/- the proximity to metal.
Total inductance 125uH using #20 AWG high temp Formvar???