[Boatanchors] Patterson PR-12 Help Needed

[Al Klase]

Joe,

You really only need four pins. One for each plate, and one for each end 
of the field coil. The "high" end of the coil connects to the output 
transformer center tap on the speaker. Take a look at the National 
NC-100 schematic: http://www.nostalgiaair.org/PagesByModel/407/M0012407.pdf

Al

On 3/22/2014 10:48 PM, Joe Connor wrote:
> I picked up a Patterson PR-12 at a hamfest today and need some information. According to the Radio Blvd. site, this is a rare set: After engineer Ray Gudie left Patterson over a wage dispute, Emmitt Patterson tried engineering the new PR-12 but soon discovered he was completely out of his element. Patterson hired Karl Pierson to complete the PR-12 but Pierson took one look at it and scraped the whole project. Though the PR-12 appeared in a few advertisements in late 1934, it was never in production.  A picture can be found here: http://n7rk.com/patterson2.htm  Note the off-center knob arrangement.
>
> Here's the help I need:
>
> 1. Does anyone have a schematic? It's not in Rider's and doesn't seem to be available from any of the usual suppliers of vintage manuals. Might it be in the Gernsback manuals? Has anyone worked on a PR-12?
>
> 2. Here's where I'm a stumped. The output tubes are push-pull 42s, yet the speaker socket is a four-prong socket. In fact, it's labeled 80, suggesting that it was scrounged at the factory from left-over parts. I've got no B+ on the plates of the 42s. A later Patterson with push-pull audio (PR-16) has a five-prong socket. B+ is fed through the center-tap of the primary of the output transformer to the plates of the 42s and the other two prongs are the field coil. How could the push-pull PR-12 work with only a four-prong socket and how could B+ be fed to the output tubes? An earlier Patterson, the PR-10, has a four-prong plug but that makes sense because it has a single output tube. I guess that I could connect the center tap of the output transformer to the prong that has B+ (after it has gone through the field coil). Does that make sense?
>
> As always, thanks.
>
> Joe Connor
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-- 
Al Klase – N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/