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It seems possible in this direction, but not the other. But I don't really know enough to make the call.
I need your advice.
The 5U4 models draw only 3 amps, while the 5R4GY draws just 2.
I don't know about the comparative voltage swings.
The maxes of the 5R4GY are all higher, but that shouldn't hurt, or am I wrong?
What more do I need to know about the PS or Output stage (2A3)to be sure?
Thanks.
Observe, before you think. Think before you open your yap. Act on the basis of experience.
Follow Ups:
You can but it will lower the B+.Duncan PUSDII can tell you what the difference will be.
You will need to know what the B+ is now and the total idle B+ current draw. Also the AC voltage of the HT winding of the power transformer and it's DCR and all the values of the parts in the B+ filter (caps, chokes etc.).
If this is your own design and you are willing to make other adjustments, it could be "better" but if this is not your design and you are simply going to change the rectifier tube you will change the design and probably not for the better.
Edit: I always think in terms of a critical choke input power supply filter because that's the proper way to build a power supply. As Eli pointed out the 5r4 will not take as big of a first cap in a cap input filter supply. You could end up just burning the whole thing down.
If you're willing (and able) to re-design the whole power supply so that it's safe for the 5r4 then you can use a 5r4, otherwise don't do it.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 06/15/14
The safe answer is don't do it. The I/P filter cap. limit for a 5R4 is lower than that for a 5U4. Also, the forward drop in a 5R4 is considerably greater than that in a 5U4. A 5R4 drops a whopping 67 V., at the rated 250 mA. of B+ draw.
Simply dropping a 5R4 into a 5U4 "hole" runs the risk of arcing and operating conditions destabilization, due to a B+ rail that's too "short".
Eli D.
5R4 MAY be OK, depending on circuit values. Peak current limit is lower for 5R4. Peak current depends on (1)transformer voltage (2) transformer winding resistance plus any other limiting resistance (3) load current (4) value of input capacitor. Voltage drop depends on load, and may not be that different, depending on current draw. Peak current is difficult to measure, but can be modeled using Duncan Amps' free PSU Designer program.
Thanks. That answers the question about the voltage drop.
It's not my amp design.
Observe, before you think. Think before you open your yap. Act on the basis of experience.
This list may help.
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