5y3gt on 6.3 ac?

[cbass]

depending on what you want to do, those 6 volt recto tubes (ez81, for example) won't do the trick. They seem to have a pretty low current/voltage limit.

I have an amp with a 6ca4(ez81) that runs 2 7591a's at 475+vdc and five preamp tubes.The 6ca4 has been in there for 40+ years.I don't know about running 2 6l6gc's though.

[Bruce / Mission Amps]

Ok I don't know my ass from a hole in the ground.They used the unused pins on the rectifier for connections to the 6.3.How in the hell I didn't catch that I don't know.Guess i'm not as smart as I think I am.

Ah, don't feel bad.
That trick is actually fairly common in lots of old time vacuum tube radios and hi-fi stuff... I mean using the unused lugs from one or more big tube socket as tie points and terminal lugs for unrelated circuits... if not at least a head scratcher, it can really throw you for a loop when trying to reverse engineer the circuit.

[jmaf]

Didn't mean to come off bitchy.I'm just not good at comunicating and it makes me seem dumber than i really am.

No sweat, buddy. Didn't take it as bitchy at all.

English isn't even my first language so I've mis-communicated plenty on this forum as well. I had long arguments here in the past and it was all about the wrong terms I was using.

[jmaf]

There was no problem with the amp just with my brain.Thanks to everyone that replied.Sorry for wasting everyones time.

Not wasting time at all, this was an interesting thread. There are gotchas all over tube amps. Bruce had the right approach to finding the problem without looking at the amp, shows how correctly thinking about the circuit in your head before even powering the amp can go a long way to solve a problem.

[R.G.]

Lower voltage is easy: use a power resistor or diodes to drop the applied voltage at normal operating current.

[Gingertube]

The power tranny maybe original and the 5Y3 not original.
If I had to take a WAG based upon what was said above it may originally have been fitted with a 6X5.
It is INDIRECTLY heated, octal base, full wave rectifier, anodes (inputs) are pins 3 and 5, heater on pins 2 and 7 and cathode (output) is on pin 8. Does that stack up with what you see?
Cheers,
Ian

[cbass]

as i stated earlier there was nothing wrong with the amp.The unused pins on the 5y3 were used for a connecting the 6.3 heaters to the rest of the tubes.Guess it was to much for my little dislexic brain to grasp.

[Prairie Dawg]

this thread has been an interesting read. For the person with the Deville, a 7Z4 is closer to what you might need in an octal or loktal base, likewise there's no problem with using a pair of rectifiers in parallel. You could even hunt up two 3DG4s, which were used in a lot of Zenith televisions, 3v winding and all. Alternatively, you might consider an auxiliary filament transformer to get your 5v chores done, if one can be found. The problem as I see it would be getting enough rectifier muscle without overloading the 6v filament string in your existing rig. That, I think would be the limiting factor.

[Cretske]

Hello folks,

Got the same problem by using an old Geloso Tranny.

It got 2 windings from 6,3V instead of 6,3V and 5V


Is it ok if I putt a 0,5 Ohm/2W resitor in series with the 5Y3Gt cathode? Would that do the job?

Regards, Cretske.

[Gingertube]

The 5Y3GT heater is 5v @2A
TDSL Tube data [5Y3-GT]

So you want to drop 6.3-5.0 = 1.3 Volts when drawing 2 Amps. You need 1.3/2.0 = 0.65 Ohms.

I would use either 2 x 1.2 Ohms in parallel (for 0.6 Ohms) in one lheater wire
OR
2 x 0.33 Ohms (one in each heater wire).
These sholud be 2W resistors minimum.
Cheers,
Ian

[olddawg]

The 5Y3GT heater is 5v @2A
TDSL Tube data [5Y3-GT]

So you want to drop 6.3-5.0 = 1.3 Volts when drawing 2 Amps. You need 1.3/2.0 = 0.65 Ohms.

I would use either 2 x 1.2 Ohms in parallel (for 0.6 Ohms) in one lheater wire
OR
2 x 0.33 Ohms (one in each heater wire).
These sholud be 2W resistors minimum.
Cheers,
Ian

Couldn't you just put in a couple of diodes back to back in series with that filament line? It would drop it .6-.7vac. That would probably be close enough? If it's an old transformer putting out a higher filament voltage because of higher modern line voltage you could use 4 diodes to drop it 1.2-1.4vac.

[EFK]

Why not just use a 6AX5?