I sold an Omni VII MX-11769 PVS-14 to a guy that claimed it was defective because it was not as bright as his friends. I accepted the return and tested it out. I think he may have adjusted the pots. The tube is super clean. Max manual gain adjustment on the housing does not result in any starring or noise like some of my other tubes. While adjusting the gain, it also will sometimes flicker and that flicker will be brighter than can otherwise be obtained. It almost feels like the autogating is preventing it from being as bright as it should. Does this sound like it could be a pot issue? Any tips for how to go about adjusting it?

If you mean the pots on the power supply ( not the ones on the lead ) then one adjusts maximum gain, and the other adjusts maximum brightness.

Generally, it's not a good idea to fiddle with these - it is possible to damage the tube.

But... If you want to, then work out which is which, and adjust maximum gain so that on a very dark night ( eg, inside a room with the curtains closed, no lights, dark outside, etc ) you can see well, but the image isn't too noisy.

Then open the curtains a bit and let more light in, and it will get too bright. Adjust the brightness pot to limit this brightness.

Then your tube is kind of tuned...

Remember, brighter = noisier.

If it's the pots on the lead, then these won't make it any brighter than the maximum brightness is set to. These are to avoid overdriving the PSU and killing the tube.

You want about 172K ohms across the lead for maximum brightness.

David.

p.s. Curious about the name... I don't suppose you happen to have a cj3?

Just to clarify, by power supply you mean the internal power supply on the tube itself right?

How do you adjust the leads?

Well like I said, this tube has a clearer image than any I've seen, but does seem like it could be a little brighter. There is absolutely no noise at all

Eta: no CJs of any type here unfortunately. It was some stupid Microsoft suggested email address handle based off my initials, favorite number, and a hobby (wakeboarding)  many moons ago

LoL! Yeah, usernames are kind of random at the time they are created, but if you get a unique enough one, that's easy to remember, it pretty much lasts a lifetime.

Yes, the pots on the main PSU control maximum brightness. If the tube is clean, then maybe find someone with a tester - If it's above the minimum darkness then it's good. A clean tube will often outperform a noisy bright tube.

So then you're adjusting the pots on the lead plug I assume? I don't know where they are supposed to be, or the exact way to adjust them. I think one controls the lowest gain and the other the highest gain.

But that's *gain* not Brightness.

You probably won't get further than halfway through the gain adjustment before you hit max brightness.

David.

Do me a favor, rig a 250k pot to the two posts on your tube, then turn it slowly until the image gets as bright as possible before the resistance gets so low it hits default. I'm betting your sitting around 100k ohm.

The real story is OP sold an old tube for a premium price and then said to the buyer that they should expect this kind of performance at this price point without revealing it was an old tube to the buyer before they purchased it.

It's like if you sell a car and don't disclose the mileage. It runs, but then when the buyer says "Hey this engine is old, it's not at peak performance though you sold it at that price" that means you didn't misrepresent the item because it still ran right?

OP, if you want to see if your tube is old, run the pot like I said and measure it. The lower you gotta go, the older and more fucked up it is. Don't bother fucking with the trim pots, you'll end up turning one too far one way and the other too far so you end up with a shitty high and an impossible low. The old saying 172k ohm is the base is kinda misleading. New tubes? Sure, I'm sure it's near there somewhere, but from my experience it's better to test, apply and set because you'll get more usage out of the tube than just keeping some basic 172k ohm to "protect" the circuit. It does need SOME protection, but I'd rather get more usage than puritan values. I mean, let's face it, manual gain bnvds that have the trim pot up front can be adjusted all the way to zero resistance and you don't see people burning tubes out cranking it to zero although anyone who runs a tube like that probably has cataracts.

If you run an old Russian tube like that, is how you get cataracts in the first place LoL!. :)