Discussion in 'Amateur Radio Amplifiers' started by W8JX, May 15, 2015.
I always put my old tubes in a vacuum chamber before I fire them up.
Nice to know it does some good.
I used to do that too, but my chamber ran out of vacuum. Got to get some more from Ebay.
TOM K8ERV Montrose Colo
"A few months", and even then quantities are limited? That doesn't sound very reassuring to me.
Lets hope they have someone over in China they can trust.
Why is there so much whining when a company is doing their best to keep your ancient stuff up and running? Give them a break. I have done production from design to sales & it is not fun at all. I lost 1/2 of my hair in 9 months.
I fully understand this and it is not a big concern of mine but I wanted to find out what I could since I live near dayton and mix it up with some players there every year to get some behind the scenes info.
I will make an uneducated guess that the reintroduction of these tubes will keep 5,000-10,000 amplifiers on the air, till some other part becomes unobtanium.
No substitute for proper procedures and methods.
3-500Zs are more prone to leaks because the kovar leads are much larger, and the pin seals have to be perfect -- which is very possible but the Chinese weren't so good at it for a long time; there's a learning curve for sure.
Graphite anodes have the getter material deposited on the anodes themselves; 572Bs don't.
I've never actually seen a 572B being manufactured. But I sure saw thousands of 811As being manufactured, back in the 70s when RCA was making them. The Lancaster plant only ran 811As about four days a month and produced about 3000 or so a month with that short shift. That was close to 'the end' of their manufacturing such tubes; much earlier, they produced a lot more back when they made them in Harrison. But those were really good 811As. The ones that passed some additional sample testing were labeled JAN tubes, as they had to meet an LTPD of 2. But the others were from the same lots and probably just as good.
No whining here. I'm amazed anybody makes them nowadays. It's a small market and for sure no 'new' products will be using them.
Not true at all. What varies from tube to tube is the getter material used. What works with a 572 does not work with a 811. Like a 3-500 you have to get a 572 glowing to getter. When used in a 811 amp, the tubes usuall do not get warm enough to getter and can fail sooner as minute amounts of air leach out of graphite over time.