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

[D C _Mac_ Macdonald]

Good to know!

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


________________________________
From: aerosmithl <aerosmithl at comcast.net>
Sent: Thursday, February 21, 2019 10:55
To: D C _Mac_ Macdonald
Cc: Gary H. Harmon, Jr.; BOATANCHORS2 LIST
Subject: Re: [Boatanchors] Multi-Elmac AF-68 and AF-68A

You can purchase all the 22 1/2 volt batteries from China with fast shipping. Check E-bay. I bought two for my Elmacs.

Sent from my iPad

> On Feb 21, 2019, at 11:41 AM, D C _Mac_ Macdonald <k2gkk at hotmail.com> wrote:
>
> 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
> (210) 657-1549 <home>
> (210) 884-6926 <cell and text>
> (210) 657-1549 <FAX with prior notification>
> gharmon at idworld.net