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Rectifier tube 5AR4 vs. 5U4GB?

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With the 5U4G, what kind of output can I expect with a 375-0-375 tranny ?

Ball park of 440, I would say.

The 5U4 heater takes 3 amps, so plan for that. There is a metal rectifier, 5T4, that is essentially a 5U4 with a 2 amp heater.

I think the 47 uF first cap will be fine - old U.S. made rectifier tubes are tough as nails. I don't think I have ever seen a bad 5U4. I have a tub full of good, used, 5U4's of all types. Most hams do .....

Win W5JAG

edit: NOS Russian "5U4"? What I ^^^^^ just wrote applies only to U.S. made tubes.

I know very little about NOS Russian rectifier tubes. I have used a few, and killed every NOS Russian rectifier tube I ever used - without trying .....
 
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In 5U4G, I have only seen CBS (Hytron) and RCA. Either would be fine. 5U4G may exist in other brands, but I don't have any. I think any U.S. made tube would be fine.

In plain vanilla 5U4GA and 5U4GB, I have GE, RCA, Sylvania, Philips ECG (JAN), and ( I think ) Tung Sol made tubes. There may be others, but I have all of these in my inventory. Any of these brands would be fine. Japanese made tubes were also very good, if those are available.

In 5T4, I have RCA marked tubes. It may have been made by others.

Sylvania also made a ruggedized 5U4 variant for the FAA and military. It is marked as 5931.

Win W5JAG
 
Ball park of 440, I would say.

The 5U4 heater takes 3 amps, so plan for that. There is a metal rectifier, 5T4, that is essentially a 5U4 with a 2 amp heater.

I think the 47 uF first cap will be fine - old U.S. made rectifier tubes are tough as nails. I don't think I have ever seen a bad 5U4. I have a tub full of good, used, 5U4's of all types. Most hams do .....

Win W5JAG

edit: NOS Russian "5U4"? What I ^^^^^ just wrote applies only to U.S. made tubes.

I know very little about NOS Russian rectifier tubes. I have used a few, and killed every NOS Russian rectifier tube I ever used - without trying .....

If we spec the tranny voltage for the 5U4G (3A) and later get a GZ34 (5AR4) which is 2A, will this cause any problems, if swapped.
 
Strictly FWIW, this is my rule of thumb:

A 5AR4 will do about 1.25 VAC in CLC configuration. So, (375)(1.25) = 469 volts.

At maximum current, a 5U4 will drop about 25 volts more than a 5AR4, so expect 443 or so from it. This is ball park, because the cap values, choke and transformer resistance, load current, individual tube, etc., will influence this. You might get a little more, or a little less.

The Russian 5U4's, I have not tried. They might be great tubes, similar to the U.S. counterparts. Or might not. I just have no experience with that tube.

Win W5JAG
 
Yes, I figure my rule of thumb with a large value first cap - 47uF. 40 uF or 33uF would be a little less voltage, but probably not very much less.

I would get 500 volt capacitors to be safe, especially if you think you might use a 5AR4 or 5V4 at some point in the future.

The 5U4 has a quick turn on, so the surge voltage will be higher than the static voltage as it waits for the power tubes to draw current, but in my experience, 500 volts will be fine - good quality caps can handle the surge.

Win W5JAG
 
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