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Philco 46-1226 confusion over tube specs

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Philco 46-1226 confusion over tube specs Empty Philco 46-1226 confusion over tube specs

Post by Brianruns10 on Wed Oct 31, 2012 2:53 pm

I'm in the process of restoring to working order a Philco model 46-1226. I received it from a friend, who stated it was working at one time, but no longer. It's had a partial rewiring, with some of the capacitors replaced with moderns, but others remain. So I've no idea the competence of the job done, but it definitely wasn't thorough.

And also I'm a little confused by one of the tubes on top of the chasis. It is a 7AF7, which is also what is specified in the tube replacement label pasted inside the radio cabinet. But all the specs and schematics I've downloaded say this tube should be a 7F8.

Obviously I don't want to fire this up until I know for sure which tube is correct. Or are both tubes functionally synonymous, and either are safe to use? This would be very helpful to know, since of course I'd like to avoid having to buy a new tube, if the one I have is indeed correct.

I'm sure I'll be posting more, but in general have you all any advice on this type of project? It's my first stab at a serious rewiring of a radio, and needless to say, the schematics are certainly a challenge to decipher!

Best,

Brian R.

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Philco 46-1226 confusion over tube specs Empty Re: Philco 46-1226 confusion over tube specs

Post by Leigh on Wed Oct 31, 2012 6:09 pm

You definitely should NOT fire it up until you're replaced all the paper capacitors, some of which are in the little Bakelite "tubs", and all the electrolytic capacitors.

In general it's wise to use the information provided with the radio. Frequently changes were made during production that don't propagate into the general documentation.

- Leigh

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Philco 46-1226 confusion over tube specs Empty Re: Philco 46-1226 confusion over tube specs

Post by mr_ed01 on Wed Oct 31, 2012 11:01 pm

Look at the filament connections of the tube in question. If filament wiring is connected to pins 1 and 8, it is a 7AF7, if the filament is connected to 2 and 7 then should be a 7F8

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Philco 46-1226 confusion over tube specs Empty Re: Philco 46-1226 confusion over tube specs

Post by jerryhawthorne on Mon Nov 05, 2012 8:22 pm

First I would look for the production code on the back of the radio, usually a number like "Code 121" or such. Then I would go to the link I'm attaching and order documentation on your radio. You will get nice large clear schematics and all the information Philco produced on that radio. I do it for every Philco I work on.
Good luck on sorting out what is in there.
Jerry

http://www.philcorepairbench.com/schematics.htm

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