[Amps] Alpha 86 Plate RFC

Paul w8aef at q.com
Tue Jan 29 10:58:27 EST 2013

I found my RFC fabrication note:

Built the choke, fabricated a delrin cam attached to the Alpha’s bandswitch 
shaft that would operate a microswitch that in turn operates a relay to 
switch the 2nd section of the RF choke in for 80 & 160 operation (idea 
stolen from a Dick Byrd modified amplifier) and my 3 tube Alpha 76CA now 
works fine on all bands from 1.8 to 32 MHz.

My version of the 86 choke consists of 100 turns of 23 gauge enameled wire 
for the 40-10 section and 43 turns for the 80 & 160m section wound on a 3/4” 
diameter x 6 1/2” long delrin form that I found on eBay.

I used the antenna relay salvaged from my #1 Alpha when I converted it to 
QSK and copied the switching circuit from the 86 manual.

Now I have two amplifers with the reliability of a concrete block and 
capable of running full power output on all HF bands.

de Paul, W8AEF


-----Original Message----- 
From: rick darwicki
Sent: Monday, January 28, 2013 6:43 PM
Subject: [Amps] Alpha 86 Plate RFC

Anyone know the uh of each section or the total uh of the Alpha 86 switched 
plate choke?


Rick, N6PE 

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