I think I may have a bad tube in my 811H. Where would you guys suggest I go to buy a good pre-tested matched set? Thanks, Robert
They don't really need to be matched in the 811h design but I'd look at RF Parts for their warranty on tubes: https://www.rfparts.com/tubes/tubes-811a.html
I purchsaed a matched quad of new Penta 811A Tubes on Ebay and they have worked fine for the last six months.
Are you kidding? $82.00 apiece, nope I have not even slightly considered it. But what I did find is a SS washer laying in the bottom next to one of the tubes. It's supposed to go between the board and the ceramic tower. So I reinstalled all the tubes, and I no longer am blowing fuses, but one of the tubes is not lighting up. That was probably the one laying next to the washer. I'm going to call HRO and ask if this is a warranty issue.
If you do wind up needing to order a new tube or tubes, I would go with RF Parts. I bought a set of 4 for my 811H back in September of 2015 and they are still going strong with the output that they had when newly installed.
You can purchase 4 "matched" 572B tubes for just over $200. https://www.ebay.com/itm/4pcs-Match...-Vacuum-Tube-upgrade-FU811-811A-/263472607904 or similar prices on eBay and Amazon. Glen, K9STH