Salvage old HiFi transformers Dyna, Eico ?

[chopstuck]

Just got a couple of old Dynaco FM tuners one mono, one stereo both picked over for parts. No real useful tubes.
I also have an old Eico HF-61 mono preamp and some big mystery home built test gear from a collection. Question is are the tuner transformers any good for building preamps ? They drive like six 6v signal tubes so my heater current is there. The whole thing may only be worth $15-20. But reverb power transformers cost about that. Hmm.

Any input ?
Also got a few cases of oddball weird heater voltage tubes. 2,3,4, 5, 8 11 15 18 19 25 50 volts.
I could build stuff without power transformers, Yea, Zap ! die alone in the basement.....

Maybe dump those locally. I got lots of fun crap for (only $100) ?

Too much value by the pound......

Reselling these may be more work than reward.

[Phil_S]

In general, tuners and preamps don't draw much current so the PT is likely not that robust. You might find out some of them are only good for 40mA. With that on tap, you might still be able to build a 2x EL95 amp. You might gang two PT's on one chassis, build 2 power supplies. One for the power tubes and one for the preamp. I think you're getting the picture -- more trouble than it's worth. Good luck with them.

[JMFahey]

Just got a couple of old Dynaco FM tuners one mono, one stereo both picked over for parts. No real useful tubes.

Not such a thing
I mean, probably you can't pop them straight into your Fender or Marshall, but the World does not end at 12AX7

*Any* tube (excluding rectifiers, that is) can be used as a triode, you wire all superfluous grids (yes, in a tuner you can even find an heptode) to plate, except suppressor which should be grounded, and voila, you have a triode.

As of biasing, either do it the scientific way by getting datasheets, or the home experimenter way: connect plate to +B through a reasonable resistor (47k to 100k) and vary cathode resistor until plate sits at about 1/2 +B or somewhat higher.

I made a small box for that, with two crocodile clips to connect from cathode to ground , inserting a rotary switch which allows me to select resistors from 820 to 4700 ohms, one of them will be close enough and then I solder the chosen value to the socket.

Beware of strong pops/thump while switching, but it's done only once, then I write cathode resistor value on a small label glued to the tube and toss them in a shoebox for future use, an experimenter's treasure trove.

A crazy German friend living in Rio de Janeiro makes killer amps using *only* "TV tubes" , here's a sample of his work:
https://www.youtube.com/watch?v=SXSzlLYQY_M

The point is: "a tube is a tube"

Worst for odd tubes is having proper sockets, may be 7 pin, locktals, European "U series", rimlocks, etc, so take care to salvage them and keep them with the tubes until needed.

Also got a few cases of oddball weird heater voltage tubes. 2,3,4, 5, 8 11 15 18 19 25 50 volts.

You can safely ignore these, although I once bought 1000 assorted ECC/PCC189 dual triodes which have respectively 6.3 and ~7,5V filaments (couldn't resist at 25 cents each) and wound a tapped filament winding (I make my own transformers) so I can use either, could also use a somewhat higher filament voltage and add a small resistor (a couple ohms) when needed to fine tune voltage or plain wind a 7V one, both tubes can be used, one will be 10% high, other 10% low, well within specs.

There's more than one way to skin a cat

[Mr. dB]

Does the stereo Dyna tuner still have its magic eye tube?