Vintage Valves - Ideas anyone ?

[Greenhill]

I got a old radio from the mid-50'es and took all the components.
I've made a handful of stompboxes and I know schematics and stuff - but I know nothing of valves..

Got some vintage valves - what to do with them ?




From left to right - UL84 - UCC85 - UCF80 - UCH81 - UABC80

[Johan]

european tubes. the U as first letter in the name means "unversal heater"  wich means 100mA / 26 volt. So the UL84 is like a EL84 (probably the poweramp in your radio )and UCC85 is a dual triode with dissapation like a 12AU7 but more gain (Mu around 45, dissapation 2.7watts...cool tube )
the UCF would be a triode and a small signal pentode in the same bottle, but I have never used that one. the two other I dont know about, but it's easy finding out by looking on the web
J

[Greenhill]

Nice enough !

Soooo..... UL84 and UCC85 would be common to use in a small valve-amp project - right?

- if I can find a project using that kind of tube :p?

[merlinb]

Soooo..... UL84 and UCC85 would be common to use in a small valve-amp project - right?

- if I can find a project using that kind of tube :p?

Just look for a project that uses EL84 + ECC83. You can sub in your UL84 and UL85 instead, and the only thing you'll need to do differently is the heater supply (find a 45V transformer).

[Greenhill]

..."unversal heater"  wich means 100mA / 26 volt

...(find a 45V transformer).

Uhmn...

26V or 45V ?

[Johan]

..."unversal heater"  wich means 100mA / 26 volt

...(find a 45V transformer).

Uhmn...

26V or 45V ?

put them in series...thats they way they were intended

[Greenhill]

Thanks !

[merlinb]

26V or 45V ?

UL84 needs 45V. I would put a 200R 5W resistor in series witht he UCC85 so it can also run off 45V.
Also, you can get 0-18, 0-18V transformers cheaply, which would give roughly 45Vdc after rectification. You could even run the whole amp off 45Vdc if you made a semi-starved circuit.

[newfish]

Would it be too difficult to give a 26v / 12v heater switch?

This way, you have a more 'universal' amp - and can sub-in those 'big name' 12AX7s for more gain...

[Greenhill]

I'm new to tube amps, and I have no idea what your talking about

I think I'll make a valvecaster - running on 12V ?

[amptramp]

UABC80 is a triode - triple diode with the same pinout as the 19T8.  The triode has a µ of 70 but is slightly different from a 19T* - the transconductance of a 19T8 is 1.2 mA/V and Rp is 58 Kohms at 250 volts whereas the UABC80 has a 28 volt 0.1 amp heater and transconductance of 1.45 mA/V and Rp of 48 Kohms at 170 volts on the plate.

The UCH81 is a triode-pentagrid mixer that is used as an oscillator/mixer for AM and usually as a straight amplifier for FM.  Characteristics of all five are here:

http://scottbecker.net/tube/sheets/030/u/UCH81.pdf
http://scottbecker.net/tube/sheets/030/u/UABC80.pdf
http://www.r-type.org/exhib/aah0017.htm
http://scottbecker.net/tube/sheets/030/u/UCC85.pdf
http://scottbecker.net/tube/sheets/030/u/UL84.pdf

[iccaros]

I'm new to tube amps, and I have no idea what your talking about

I think I'll make a valvecaster - running on 12V ?

What Merlin is explaining is how a tube heats it cathode and he gave you values so that you can use a single voltage for both tubes. Tubes require heat to work as they are thermal conductive devices. So the heater coil heats the cathode boiling off electrons. The gates or screens control which direction these electrons flow.
If you have a tube that requires one voltage (26) and another that requires another (45) than it is easier to run both to the same supply but you need to drop 19 volts. So the value he gave is what it will take and the amount of wattage it will dissipate.

While you could create a valve caster, you would still need the 45 volts for the heater, so you might as well make a 45volt valve caster.

He was also suggesting that you could make an amp from these tubes using 45 volts.  With a high efferent speaker (like a red Coat Wizard)  it would make a good practice amp.

[Greenhill]

Thanks everybody!.. I'll check what spare parts I have lying around and think of a good project for these

[amptramp]

Actually, you could use a 71 volt supply and run the heaters in series with no need for a dropping resistor.  After all, that is how they were connected in the original radio.