[ARC5] Selenium rectifiers

[Kenneth G. Gordon]

On 12 Mar 2022 at 15:38, Jack Antonio wrote:

> But yeah, I do treat seleniums with suspicion.

Well, everyone here can, of course, do what they wish with regard to selenium rectifiers, but I 
won't have them in the shack if I can avoid it.

Most will deteriorate over a long period of time, some even while being stored. They become, 
essentially, resistors, not rectifiers.

Then, if they short out under load, they spit out a gas that is poisonous, besides stinking to 
high heaven.

IMHO, it is far less hassle to simply replace them with silicon. than to continue to worry about 
them...and I am NOT in favor of shot-gun replacing any other component without testing it 
first.

I can't and won't trust the darned things.

In the unit in question, we were told that the selenium rectifiers in this rotary converter are in 
the voltage-regulation part of that unit. By the very fact that those are in that part of the circuit, 
I would be replacing them even if they "test" good....for now.

Although I am not "intimately" knowledgeable of that particular circuit, it seems to me that if 
they control the voltage regulation of the unit, it would be far better to replace them, now, with 
silicon rather than depend on such an iffy component.

It also seems to me that if that voltage-regulator was not completely up to specifications, that 
COULD be the reason for the unusually high current the unit exhibits at no load. If there was 
more AC on the output of the selenium rectifiers than there should be, for instance.

Of course, you MAY have to consider and account for the differing voltage-drops of selenium 
vs silicon, but in most cases that won't matter.

But since it is your equipment, you can do as you want.

Ken W7EKB