[Boatanchors] Multi-Elmac AF-68 and AF-68A

[D C _Mac_ Macdonald]

Hi, Gary.

I could not find anything through Google about the differences.  However, the originals had two known problems:  1) Modulator driver transformer quickly went bad, frequently replaced. 2) Negative 22.5 Volt Bias for 6L6 modulator tubes derived from a 22.5 Volt battery with short life (try finding one today). Build voltage doubler from 12.6 VAC filament supply and then hand-select Zener diode(s) to get to 22.5 Volts.

The "A" model MAY have fixed one or both of those problems.


73 de Mac, K2GKK/5​
Since 30 Nov 1953​
Oklahoma City, OK​
USAF, Retired ('61-'81)​
FAA, Retired ('94-'10)

________________________________
From: boatanchors-bounces at mailman.qth.net <boatanchors-bounces at mailman.qth.net> on behalf of Gary H. Harmon, Jr. <gharmon at idworld.net>
Sent: Thursday, February 21, 2019 09:46
To: 'BOATANCHORS2 LIST'
Subject: [Boatanchors] Multi-Elmac AF-68 and AF-68A

Looking for a schematic or manual for a AF-68A in order to determine the
differences in the two.



Thanks in advance.



Gary H. Harmon, Jr. - K5JWK - HAM Radio and ATARI Archaeologist

6003 Archwood

San Antonio, TX 78239-1504

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gharmon at idworld.net



"Retirement = Every day is a Saturday except Sunday"

"Real radios glow in the dark"

"Too many projects, not enough time"



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