I've just completed a pair of Rod's filament regulators. I purchased them about 4 years ago, so they aren't the most recent version.
It's lighting up a 3c24 which is 6.3v 3A.
Everything appears to be working properly. But, the voltage slowly drops about .6v over about 10 minutes after I power it on. So to set it at 6.3v it starts off at about 7v for a good 5-10 min while it's all warming up.
I expected a voltage change as things warmed up, but not this much or this slowly..... I guess that's how long it takes the heat sinks on the reg to get to their steady operating temp.
Is this normal?
Thank you.
It's lighting up a 3c24 which is 6.3v 3A.
Everything appears to be working properly. But, the voltage slowly drops about .6v over about 10 minutes after I power it on. So to set it at 6.3v it starts off at about 7v for a good 5-10 min while it's all warming up.
I expected a voltage change as things warmed up, but not this much or this slowly..... I guess that's how long it takes the heat sinks on the reg to get to their steady operating temp.
Is this normal?
Thank you.
I am about to build a 300B PSU using Rod's latest version (V. 7) regulator. When making the final adjustment for the 5V I was told to wait about 1 hour. After this it should not be necessary to make any further adjustments of the lifetime of the tubes.
When starting from cold I was told that it could take up to 3 min. before the filaments has reached a temperature so it was safe to apply the B+.
So 5-10 min could be the time needed before everything is resonable stable.
On the V. 7 regulator there is a NTC resistor which needs close contact with a transistor. Think this is for temp. stabilization.
I will see when I have finished my PSU how it behaves.
If you write a mail to Rod I am sure he will answer it. Maybe he will respond directly to this thread.
When starting from cold I was told that it could take up to 3 min. before the filaments has reached a temperature so it was safe to apply the B+.
So 5-10 min could be the time needed before everything is resonable stable.
On the V. 7 regulator there is a NTC resistor which needs close contact with a transistor. Think this is for temp. stabilization.
I will see when I have finished my PSU how it behaves.
If you write a mail to Rod I am sure he will answer it. Maybe he will respond directly to this thread.
Oh, thanks. I read the circuit was temperature compensated, which is why this much of a change concerned me. But, maybe that's just the new version. I looked at the v.7 instructions, and mine does not have that NTC resistor.
So, if mine isn't temperature compensated, I guess this makes sense.
So, if mine isn't temperature compensated, I guess this makes sense.
The regulator runs at a fixed current, and you are measuring voltage. As the tube heats up, the voltage WILL change. This is normal and expected. It is not drift of the regulator you are seeing, it is drift of the tube. As the tube heats up, its filament changes resistance. It takes a long time for this to stabilize.
Yes, as Zizag says, the Regulator limits the filament current to the nominal rated value (so, 1.2A for a 300B), and the voltage rises slowly (avoiding sudden shocks to the filament) and it is best to adjust it for the final time, after running a little while.
The earliest versions were uncompensated, and took longer to stabilise. The latest V7 has carefully optimised temperature-compensation, and shows very low drift, even after long-term use.
The earliest versions were uncompensated, and took longer to stabilise. The latest V7 has carefully optimised temperature-compensation, and shows very low drift, even after long-term use.
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