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Transformer specs [message #9351]

Thu, 24 November 2005 13:53

Tickfawriver
Messages: 6
Registered: May 2009

Esquire

I recently picked up a second Motorola mono amplifier chassis of the quad 6V6 variety. I am looking for the specs on the power transformer, part number is Magnavox 300067-04 394322. It could possibly be 300067-G4. I have two such chassis and this one has a larger transformer, I am hopeing to build a stereo out of the two mono amps.

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questions [message #9352 is a reply to message #9351]

Fri, 25 November 2005 05:27

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

I can't give you specs from a Magnetbox part number. Tell me a bit more about the amplifier, and I will tell you want it requires.

Now many 6V6?
Are they Push-Pull, or Single Ended
Other tubes? and number of each?
Any other details that look important?

cheers,
Dogulas

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Re: questions [message #9353 is a reply to message #9352]

Fri, 25 November 2005 15:47

Tickfawriver
Messages: 6
Registered: May 2009

Esquire

Here is a schematic. http://www.triodeel.com/mag278.gif

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Re: questions [message #9354 is a reply to message #9353]

Fri, 25 November 2005 16:45

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

hmmmm...push-pull-parallel 6V6's. Plus the pre-amp tubes. Say 160 mA at between 275 and 325 volts. Pick your filter type, and rectifier and PSUDii will spit out the rest.

You were not quite clear in the original post. You wish to make one more of these? Or you're going to rebuild one with a bad power TX?

Instead of parallel 6V6, I'd suggest single pairs of 6L6GC.
cheers,
Douglas

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oooohhh! neat trick [message #9355 is a reply to message #9353]

Fri, 25 November 2005 16:58

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Using the g2 supply from the PPP amplifier for the anode supply of the SE amp. Nice touch. I'd refine the estimate of required current by another 40 mA, and say the main HV is probably ~300 V or so. Text book SE is close to 250v to the anode.
cheers,
Douglas

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Re: questions [message #9356 is a reply to message #9354]

Fri, 25 November 2005 21:41

2wo
Messages: 44
Registered: May 2009

Baron

That is pretty cool, I don’t like parallel tubes but if 1 6v6 is enough power, try it…John

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me neither... [message #9357 is a reply to message #9356]

Sat, 26 November 2005 05:17

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

see the anode chokes between the anodes? Too much temptation for the oscillation bugs to creep in and work. They are sometimes like the proverbial NY cockroach when trying to get rid of them.

no offense to the cockroaches...:)
cheers,
Douglas

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Re: questions [message #9358 is a reply to message #9354]

Sat, 26 November 2005 06:06

Tickfawriver
Messages: 6
Registered: May 2009

Esquire

I plane to build a stereo amp useing the larger of the 2 power transformers and the output transformers. The larger pt was "made to fit" and not the original and I was hopeing it could drive 2 6L6 pp's but I may be hopeing for too much. Basically I have 2 mono quad 6V6 pp amps and I want to put them together.

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Re: questions [message #9359 is a reply to message #9358]

Sat, 26 November 2005 06:16

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Two of those quad 6V6 amps are going to draw more than 320 mA each. That's a big transformer by most standards. I would call Heyboer Transformers in MI, and get a custom wound. Specify all the heater current you'll need and run with it. It depends on how you want to run the filter, as that will dictate the AC voltage. L-C will be ~340vac, and CLC or CRC would want more like 250vac.
cheers,
Douglas

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Re: me neither... [message #9360 is a reply to message #9357]

Sun, 27 November 2005 06:48

Tickfawriver
Messages: 6
Registered: May 2009

Esquire

I am not going to rebuild acording to the Mag schem I am just going to reuse the transformers and I guess I will go with one pair of 6V6's pp for eah channel. I was just looking for a way to squeeze out a little extra power.

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