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Odd Tube Find

jaymanaa

jaymanaa

RIP 1961-2018
Anyone got anything on the 5608? I haven't been able to find anything except that it's a twin triode, which I could already see. It looks like two 76 type triodes in a single bottle with two side and one top getters. The sticker on the tubes says; Caution, use only on capacicontrol circuits. Replace the tube when top becomes cloudy white. I think it may have been used in capacity control systems for early air conditioning. I got them for 10 apiece new in their original boxes, so I'm hoping they will sound as good as the triple getters look. A spec sheet and triode curves would be awesome. Oh, they also have a metal shield between the triodes. They look like a very high quality tube.
 
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It's listed as a ck5608 in this photo.

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Thanks man, that actually looks a little better than a 76. I think I'll go get the rest of them tomorrow. 300v, 6ma, AF32, 2450mhu, and a 2.5 volt fil. I'm thinking driver maybe for paralell 2A3 job. Any other ideas?
 
Scuzzer said:
It looks like it shares a cathode between the two triodes. Maybe it was designed for mixing duty?
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Interesting, I bet if I could find an old industrial AC guy he would know something about it. Wait a minute, I am an old industrial AC guy. So much for that, I'll try videokarma, thanks guys. What's your opinion for audio use Scuzzer?
 
Dunno. I'm more of a wire it up and try it sort of guy, especially when there aren't any curves available.
 
Scuzzer said:
It looks like it shares a cathode between the two triodes.
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Many PP output circuits have the two tubes' cathodes connected together anyway. I've seen stereo single ended amps where they had both cathodes connected to teh same resistor and bypass cap.

Or use it as a long tailed pair.
 
wa2ise said:
Many PP output circuits have the two tubes' cathodes connected together anyway. I've seen stereo single ended amps where they had both cathodes connected to teh same resistor and bypass cap.

Or use it as a long tailed pair.
Click to expand...

ltp might be just the ticket :yes: I've got a stash of those Martian looking tubes with twin top caps on them that share cathodes as well. Little ones for drivers and big ones for power. I think they will make a cool looking amp.:yes:
 
Scuzzer said:
I wonder what they're used in to command prices like those?
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I'm just guessing, but maybe SET amp drivers. Some of those, don't have the triple getters like mine either. I wonder if it's the Asian market driving the price up.:dunno:

I certainly would have never guessed they were that valuable. I don't flip anyway though, it just makes me think maybe they do sound good.
 
wa2ise said:
I've seen stereo single ended amps where they had both cathodes connected to teh same resistor and bypass cap.
Click to expand...

I used a 6J6 for my little headphone amp so that I could switch the cathode bypass cap to smooth out the hard right/left panning on some early records. Big cap - big separation, small cap - little separation. It worked surprisingly well.
 
My first thoughts are LTP splitter since the cathodes tie together anyways, or parallel
both sections an use as a gain or preamp tube, either should work well I'd think there.
 
Kegger said:
My first thoughts are LTP splitter since the cathodes tie together anyways, or parallel
both sections an use as a gain or preamp tube, either should work well I'd think there.
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Going by mu and gm, that one has a plate resistance of ~10kOhm. A LTP splitter with a light load( EL84 for instance ) comes to mind. Even the big power tubes, if rig'd as pentode are not much of a load.

So, to get totally nuts, 4-65 as input pentode, and a 304TL as concertina to drive 6V6's...:)
cheers,
Douglas
 
jaymanaa said:
Interesting, I bet if I could find an old industrial AC guy he would know something about it. Wait a minute, I am an old industrial AC guy. So much for that, I'll try videokarma, thanks guys. What's your opinion for audio use Scuzzer?
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I'm a retired industrial technician/electrician and I've worked on old temperature equipment. That tube is used in an old Barber Coleman temp. control. They didn't use those old controls anymore, so I was able to take the tubes home. Is there a brass strap soldered across two pins? When I first looked at the tubes I thought of a 6A6. I never looked at the specs.
 
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