late last year I purchased a Ameritron 811-H amp. First amp I have had in years. Back in January i posted on this list my problem that I had blown a grid resistor on the back right side tube. With th
Dave, Thanks for the reply. I do have an added question. Would I be seeing parasitic conditions before and without any RF ye? This has happened only when i switch the amp on (power switch) still in s
Interesting. Just so you know that you are not alone - I had exactly the same problem (exact same tube position and the exact same failure!) with an AL-811H that I had some time ago - and - it happen
I doubt that this problem is caused by a parasitic. I certainly would not make a categorical statement like 'you are getting a parasitic oscillation...'. It sounds like, more than anything else, a tu
Thanks for the response one reason a buddy has thought of that same tube is it could be the first one in line taking some type of surge at switch on it was R 19 and both times the rear right side tub
To find out if it was a parasite or not, measure the ohms of the parasitic suppressor R on the tube that blew it's grid R. If the ohms are still within tolerance, it was likely not a parasite. - I ha
Even with the amp in standby? Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
I was not there when it happened, I saw the 3 casualties after a Ham brought the AL-811 over for a post mortem. As I recall, he said he heard a pop after concluding the power measurement, and the thr
The original post described resistor damage when the amp was in standby and with no rf applied. In that situation parasitic, or any other, oscillation seems highly unlikely. Steve ___________________
Steve -- At one time. I used to make this argument, but not any more. Then - In the days of radio yore, spark transmitters crudely made RF by rapidly switching DC on and Off through a high-Q resonant
I wouldn't believe it either if it weren't for years of servicing RF amps. Some of the old G-G sweep tube amps were so prone to self oscillation, that the cathodes were killed all together on idle to