I just paid for (hasn’t arrived yet) a NOS Merit A-2903 output transformer because it was cheap.
12k:3.2 SE (10 mA DC), 5W. It appears in a 1951 Merit catalog, but not 1966.
The 3.2 ohm secondary suggests a common voice coil impedance of the era so it probably really is intended for a speaker. I could look at it also as 15k:4 or 30k:8 and use it for an extra-tiny SE pentode or triode amp...just...because...
Anyone have any idea how lousy the freq. response was for that series of xfmr’s? (Could be for 300-3000 Hz communications gear...).
Or maybe robust enough for some kind of reverb I don’t need at the moment but could add to a tiny amp?
Thanks
12k:3.2 SE (10 mA DC), 5W. It appears in a 1951 Merit catalog, but not 1966.
The 3.2 ohm secondary suggests a common voice coil impedance of the era so it probably really is intended for a speaker. I could look at it also as 15k:4 or 30k:8 and use it for an extra-tiny SE pentode or triode amp...just...because...
Anyone have any idea how lousy the freq. response was for that series of xfmr’s? (Could be for 300-3000 Hz communications gear...).
Or maybe robust enough for some kind of reverb I don’t need at the moment but could add to a tiny amp?
Thanks
You have the catalog? It does identify it as a tube output transformer? Remember this the era of germanium transistor OPT's as well.
Just treat is as a 4 ohm secondary.
Just treat is as a 4 ohm secondary.
Thanks...not much more info than what I typed...I was hoping someone could throw a dart at a quality target...somewhere between 1950’s shortwave radio and Magnequest...but I’m pretty sure it’s at the edge or off the target...better than using a power transformer as OPT.
I won’t get my hopes up & just use it & see what happens...maybe a tiny triode-pentode amp to swap random tubes (with same pinout!) into.
PDF catalogs (whole library). Site has weird name, but apparently harmless...
Antique Transformer and Parts Catalogs and Specifications
I won’t get my hopes up & just use it & see what happens...maybe a tiny triode-pentode amp to swap random tubes (with same pinout!) into.
PDF catalogs (whole library). Site has weird name, but apparently harmless...
Antique Transformer and Parts Catalogs and Specifications
On page 4/12, 14th line item, 6K6 typical tube, as ‘receiver replacement’ ...kind of lo-fi I anticipate...maybe not as cheap as I thought...I won't look at 1951 price ($2.20 !)
http://www.bunkerofdoom.com/xfm/merit_1951_web/merit5111_002.jpg
http://www.bunkerofdoom.com/xfm/merit_1951_web/merit5111_002.jpg
BunkerOfDoom has been around forever. Harmless geek.
12K 10mA means only 120V peak swing. Taking a pentode and 40V drop, use 160V supply; somewhat more for a triode. Expect 0.6 Watts, not 5W! (5W is the core size, but the DC current rating does not allow near that much.) The 6K6 does have a rating for 110V supply, 9.5mA, and 0.35W out. I'd expect "small communications receiver", but it could be better.
BTW, FWIW: I keep saying lower Z is lower cost. Here we have prices for similar parts at several impedances.
12K 10mA means only 120V peak swing. Taking a pentode and 40V drop, use 160V supply; somewhat more for a triode. Expect 0.6 Watts, not 5W! (5W is the core size, but the DC current rating does not allow near that much.) The 6K6 does have a rating for 110V supply, 9.5mA, and 0.35W out. I'd expect "small communications receiver", but it could be better.
BTW, FWIW: I keep saying lower Z is lower cost. Here we have prices for similar parts at several impedances.
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The little Merit guy arrived...
I like your EL34world.com post on the 5654/6AK5 as a SE PA, and the 5670...I don't have any 6K6's, anyway...just a 6K6-suitable transformer.
Since I'm talking hundreds of thousands of microwatts anyway, I have several 5654, 5694 (6J6), 7060 ('13AU8'), 12AU7, 12AT7, and dozens of 6CB6's, so I think I'll grab a 5654 and go compare datasheets for my other triodes (single or parallel) to the 5670 and compare the other pentode datasheets too.
All this may help me find a use for two puny NOS Heathkit SE opt's...also therefore wondering why I bought another this weekend (you can't help me with that problem).
Anyway, gotta go walk the dog...his walk may be more productive than my shopping.
Another weirdo output transformer will show up this week...1500:4/8/16 '120 W' NOS for Kustom Double Cross...looks like might do for a PP pair of 6C33C-B at less power.
Just because...
I like your EL34world.com post on the 5654/6AK5 as a SE PA, and the 5670...I don't have any 6K6's, anyway...just a 6K6-suitable transformer.
Since I'm talking hundreds of thousands of microwatts anyway, I have several 5654, 5694 (6J6), 7060 ('13AU8'), 12AU7, 12AT7, and dozens of 6CB6's, so I think I'll grab a 5654 and go compare datasheets for my other triodes (single or parallel) to the 5670 and compare the other pentode datasheets too.
All this may help me find a use for two puny NOS Heathkit SE opt's...also therefore wondering why I bought another this weekend (you can't help me with that problem).
Anyway, gotta go walk the dog...his walk may be more productive than my shopping.
Another weirdo output transformer will show up this week...1500:4/8/16 '120 W' NOS for Kustom Double Cross...looks like might do for a PP pair of 6C33C-B at less power.
Just because...
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The 6AK6 tube may work here. If you bend the specs on the little transformer to 15 mA the 6AK6 can blast out a speaker destroying 1.1 watts! throttle back the B+ a little for 10 mA or so. The 6AK6 has a 150 mA heater so it's a good choice for a battery operated project. The 6AQ6 triode has a similar heater and a high Mu. It makes a suitable driver tube. These two could make a little portable tube guitar amp.
And 6G6G if you want a more stylish bottle.
I ran a pair of 30 - 40 ma ish A-2930's, with some 6N6G, for several months in place of Edcor XSE-15, while the latter were being used in another project. At normal listening levels, I thought they were fine. They didn't do well on a 60:6000 SMPTE IMD test, but I didn't expect them to.
I would expect the smaller ones to be good, within their current and power limits. Frequency response will be much better than 300 - 3000 if those are anything like the 40 ma OPT's.
Win W5JAG
I ran a pair of 30 - 40 ma ish A-2930's, with some 6N6G, for several months in place of Edcor XSE-15, while the latter were being used in another project. At normal listening levels, I thought they were fine. They didn't do well on a 60:6000 SMPTE IMD test, but I didn't expect them to.
I would expect the smaller ones to be good, within their current and power limits. Frequency response will be much better than 300 - 3000 if those are anything like the 40 ma OPT's.
Win W5JAG
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