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In Reply to: Re: Tube amps blowing fuses posted by John Chleapas on August 28, 2006 at 13:12:49:
I have bought new matched quads in the past that had duds in there. One set lasted about 5 hours and then one of the new tubes shorted out. Just because the tubes you use are recent does not always mean that they are good sadly. John
Follow Ups:
Thanks for the response. The question remains as to whether the ground plug removal could be a factor to the problem, so if you have an opinion on that I'd appreciate it. I'll know soon enough if the removed ground plug is the issue now that I've replaced that cable, but it would be good to hear the word from more experienced folks than myself about how important the ground is to tube amps.I do have a Vacuum Tube Valley Tuber Characterizer that works great for the small signal tubes, but I would appreciate some advice for a tester that will also work also for EL34's and especially for the big 211 power tubes that the Jolida JD3000's use. I'd prefer something new and modern, rather than something old and in need of regular calibration. I also need something with easily comprehensible instructions and explanations of what is being measured, as the terminology used for much of the tube calibration issues is a total mystery to me.
Your help would be much appreciated.
Try contacting Jim McShane or Ed Sawyer or some of the other AA members with excellent references who sell quality matched, new, and tested used tubes on the side earning some money to feed their audio habits. Perhaps you can pay your tech to mount a surface or a side mounted bias meter on your amplifier similar to how Airtight does it on their 211 mono blocks? By doing that it allows their 211 owners to set the bias on the 211 output tubes while running in their own amps.On your other question about tube testers there is tons of information and sites about tube testers. I own three working ones. I missed a nice top of the line solid state Triplet tt after I had my Hickok 539b fully calibrated and restored. Most all of these tube testers are 50 and now going on 60 years old. But with a very good going over by a qualified tech they will last for another 50 years no doubt. Sadly I had one of the last tube testers restored and calibrated by Chris Haedt before he passed away a few years ago. I wonder if some of the early military tube testers ever came with optional plug in modules, or adapters to test the 211 and 845 tubes? My favorite daily beater tube tester is my humble Sencore Mighty Mite in its rugged metal case. Just cruise the web sites on tube testers and read a lot. If you buy one the important thing is that it is working and the meters are working. It should also have the manual or the roll chart with it. Once you find a decent working one a visit to a few boat anchor sites and/or ham radio swap meets should get you in touch with a qualified tech to calibrate and repair it. I have seen some lower end tube testers on Craigs list. Today some of the people selling testers on epay tend to say they have no tubes to test them to verify if it works or not. I would not buy one of the DOA, or one needing too much work. I bought one once that needed only a minor repair. When I told the seller it was missing a vital transformer he quickly refunded my money and he resold it for the same price as a "parts only unit" on ebay. Replacement parts and many meters are now made out of unobtanium. Another old timer who used to sell replacement meters for Hickok 539 series tube testers passed away recently. The last few years of his life he stopped selling those meters when he discovered ebay and started selling off his collection and parts units. He was one of the old time original bench techs at Hickok. Someone else will get desperate enough some day and commission a run of those meters once again. John
http://www.quinceton.com/airtight/ATM211.htm
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