[ARC5] 12V power pentode - some details.

[D C _Mac_ Macdonald]

Convert the original crystal oscillator socket to house a 6AG7 buffer to follow the 6AG7 that you use to replace the original oscillator tube and wire their filaments in series for 12 Volt operation ? ? ? 
 
Mac,  K2GKK/5 in OKC 

Sent from my iPad

> On Apr 10, 2016, at 22:59, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
> 
> OK, Gang, after some questions from you folks, and despite my answering some of 
> those, I thought I would fill you in on the details as they exist in my mind.
> 
> All of the ARC-5 stuff I have had were receivers. I was "gifted" 150 of them by an old 
> employer (1970s) when he died. I sold all the good ones off, and kept only the badly 
> chewed up ones, all of which would require considerable effort to get operational, let 
> alone restored to factory condition.
> 
> As far as transmitters were concerned, I had none.
> 
> Some of the kind folks on this forum, at my request, sent or sold me at a very low prices, 
> several unrestorable, most badly hacked up, transmitters to experiment with.
> 
> I've seen a lot of discussion here about putting the transmitters on the air, and one of the 
> common complaints is poor keying quality.
> 
> I thought that perhaps by changing the 1626 triode oscillator to a correctly-sized 
> power-pentode in the ECO configuration, much of those keying issues could be fairly 
> easily resolved.
> 
> Thus my question about an octal 12V power pentode.
> 
> I believed, and still do, that a very simple change at the 1626 socket, and a good power 
> pentode would be fairly easily implemented.
> 
> Trouble is, there ain't one.
> 
> I think at this point, I'll use either a 6AG7 with a resistor, or a 12BY7 and an adapter to 
> continue my experiment.
> 
> The subject is a 7 - 9.1 MHz bare aluminim transmitter which has two SO-239s mounted 
> on the front panel, a key jack, also on the front panel, an octal plug on the back panel, all 
> the original wiring ripped out, extra but empty holes in various places, a shaft and knob 
> sticking out of the side connected to the  front tuning capacitor, the roller coil removed, a 
> piece of aluminum plate covering the front where the roller coil was, and a two section 
> BC variable mouted in its place, and the final tank circuit modified for what looks like a 
> pi-net output. 
> 
> I plan to use some JB Weld to plug the holes and otherwise put it back to as close to 
> original as possible, but want to change the VFO to see if I can easily improve the 
> keying.
> 
> I'll run it on a dynamotor from a 12 V battery.
> 
> Anyway, that's the story.
> 
> Thanks for all the suggetions. I very much appreciate them.
> 
> Ken W7EKB
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