Using old radio as transformer donor

[passaloutre]

I've found at a local antique shop a Bendix Model 676 for $75 (schematic attached).

Much of the existing circuit is dedicated to the radio tuner, but I notice there is a single-ended 6V6GT amplifier as well as a 5Y3, 6SQ7, and a couple 6SK7s (maybe not as useful).

I'm not super interested in restoring it as a radio or phono amp (I have a hifi system that I like already), but wondering if it might make a good parts donor for a single-ended build. Presumably the PT can provide ample power for a few tubes, and the OT could be used as well. Of course I have no way of knowing if they work without buying it, but I wouldn't mind some opinions from you guys who have done similar things.

I'm a little confused about the resistance measurements notated on the schematic. On the output transformer there is an "8ohm" and a "2.5ohm" marked. Could I expect this to work with a regular 8 ohm guitar speaker?

[sluckey]

I'm a little confused about the resistance measurements notated on the schematic. On the output transformer there is an "8ohm" and a "2.5ohm" marked. Could I expect this to work with a regular 8 ohm guitar speaker?

I think the "8ohm" is really .8Ω which is the DCR for the 2.5Ω impedance secondary. This is not a tapped secondary. Only one 2.5Ω impedance available.

[passaloutre]

Further down the page it does say that the stock speaker has an impedance of 3.2. Would a 4 ohm guitar speaker be too much of a mismatch?

[sluckey]

A 4Ω speaker would be a good match.

[kagliostro]

To me the price is too high unless the cabinet is valuable and you want to recover that too for a particular look,  you can find other donor for less money

I'm able only to find the 676D model, is your cabinet like this ?

Franco

[Latole]

Further down the page it does say that the stock speaker has an impedance of 3.2. Would a 4 ohm guitar speaker be too much of a mismatch?

[Latole]

To me the price is too high unless the cabinet is valuable and you want to recover that too for a particular look,  you can find other donor for less money

I'm able only to find the 676D model, is your cabinet like this ?

Franco

" Of course I have no way of knowing if they work without buying it "

Yes price are a way too high to use some parts to built guitar amp

[passaloutre]

I'm curious where you can get a PT, OT, chassis, and a handful of tubes for $75?

[PRR]

...Much of the existing circuit is dedicated to the radio tuner, but I notice there is a single-ended 6V6GT amplifier
...Could I expect this to work with a regular 8 ohm guitar speaker?...

This is a tuner AND an audio amplifier. You do not need to strip it. Take it in the driveway on a long cord, power-up, wait for smoke to stop. (Sometimes they don't even smoke.) Adapt guitar (or finger) into PHONO input and switch, see if it plays (or hums).

Just like that, if healthy, it will play guitar but need a lot of arm-power. The quick fix is an LPB or other semi-clean boost in front. The other trick is to strip a 6SK7 socket (leave 2&7), wire G2 to plate, and use it as an audio triode. Maybe 100k plate and 300-1k cathode.

If you start cutting it up, 50:50 odds the unlabeled bits will sit in the garage for a decade and you will be back "What is the purple wire?"

$75 is the asking price. Show a $20 bill, sometimes they grab it. I could see going $35 but not for me. Yes you pay a LOT more than that for a PT OT sockets and tubes new, but you don't know if there is any life left in these parts. Unless you have bitter experience, bad parts are bad parts at any price.