Interesting finds...

[mchet]

Went to the flea market in Saylorsburg, PA today and found a old GE radio/turntable combo, all tube! The only tube I recognized was a GE 50L5-gt/g, but it also had 2 12SK7-gt/g's, 1 12SA7-gt/g, 1 12sq(?)7-gt/g. In think the 50L6 is a rectifier tube, but am not certain if the others have any guitar amp applications... Anyone know anything about these tubes?

I also found an old Zenith Royal 820 radio, which seems to be tube?!? I am going to do a search to see if there is any info on these to see what the deal is, but I noted what appears to be either an audio or output transformer in there...

Will post pics as soon as I can...

[ce24]

ok here you go

you have
50l6=pentode
12sk7gt=pentode variable u
12sa7gt heptode year 1941
12sq7=duo-diode+triode circa 1939

Cheers
ce24
BTW I have no idea really what those mean I just have a really cool piece of software that you just type in the tube numbers and it gives all the data, pin outs etc....

[Jenix]

Originally Posted by ce24

ok here you go

you have
50l6=pentode
12sk7gt=pentode variable u
12sa7gt heptode year 1941
12sq7=duo-diode+triode circa 1939

Cheers
ce24
BTW I have no idea really what those mean I just have a really cool piece of software that you just type in the tube numbers and it gives all the data, pin outs etc....

lol

[mchet]

Thanks ce24! I found similar information online, but can't seem to determine if any of the tube, other than the 50L6 have use in an amp...

[sjhusting]

Originally Posted by mchet

Thanks ce24! I found similar information online, but can't seem to determine if any of the tube, other than the 50L6 have use in an amp...

I'll bet there's no mains transformer in there.

Let's see 50 + 12 +12 + 12 + 12 = 98 (volts) for the heaters, there is proably a big resistor in the heater chain, too.

Some older 'cheap' amps (Silvertone and similar) used series heater tubes. The heater voltages add up to line voltage, with anything missing being burned by a resistor. Saved the cost of a mains transformer. Can put line voltage on the chassis, though, and is risky. Also violates current code, certainly, and for good reason.

The triode part of the 12sq7 has a mu of 100, like a 12ax7. I guess you could use that for something, but you'll have to wire up a 12.6V heater supply. I've got a bunch of those, but never got around to using them for anything. I just use 6SL7 when I want to go octal.

The heptode and 6sk7 are radio tubes. You can't use the heptode for anything. You could try the 6sk7 as a pentode input (preamp) stage, like a ef86, that might be interesting. I have a bunch of those, too, hmm ....

The output transformer will probably have a 3-4K primary, so you could use it to build a nice little SE 6L6 amp. A 50L6 will put out 4-5 watts, it's not likely the transformer will take much more than that.

If it's in good shape, it seems a shame to rip it apart for a handfull of octal sockets and a small transformer.

just my 2 cents

steven

[mchet]

Originally Posted by sjhusting

I'll bet there's no mains transformer in there.

Let's see 50 + 12 +12 + 12 + 12 = 98 (volts) for the heaters, there is proably a big resistor in the heater chain, too.

Some older 'cheap' amps (Silvertone and similar) used series heater tubes. The heater voltages add up to line voltage, with anything missing being burned by a resistor. Saved the cost of a mains transformer. Can put line voltage on the chassis, though, and is risky. Also violates current code, certainly, and for good reason.

The triode part of the 12sq7 has a mu of 100, like a 12ax7. I guess you could use that for something, but you'll have to wire up a 12.6V heater supply. I've got a bunch of those, but never got around to using them for anything. I just use 6SL7 when I want to go octal.

The heptode and 6sk7 are radio tubes. You can't use the heptode for anything. You could try the 6sk7 as a pentode input (preamp) stage, like a ef86, that might be interesting. I have a bunch of those, too, hmm ....

The output transformer will probably have a 3-4K primary, so you could use it to build a nice little SE 6L6 amp. A 50L6 will put out 4-5 watts, it's not likely the transformer will take much more than that.

If it's in good shape, it seems a shame to rip it apart for a handfull of octal sockets and a small transformer.

just my 2 cents

steven

Thanks Steven!!!!! As you thought there is no power transformer, but there is huge cap in the wiring so I think you nailed it.

I was actually taking stock on the radio as a whole, and think I will see if I can get the station selector working again. Currently it gets lots of static, but I think I can get it working again. Failing that I will leave it intack. Just seems like a bad idea to ruin a potential hairloom....