Heater to cathode leakage. I also tested pulls from the set and spares for it.
Heater to cathode leakage. I would replace. 6BE6's and 6BA6's seemed to be particularly bad in this respect and I obtained the following readings on an AVO CT160. . The B&K CRT rejuvenator that I used extensively in the 80's, had a specific setting for blasting off H-K leakage, which I believe was caused by material 'bubbling' off the cathodes over the years and forming a high R 'bridge' across to the cathode cylinders. ) If the hum goes away, then it's a tube issue, in the form of heater-to-cathode leakage. But it may be a worsening condition once present, depending. 6BA6 230k, 230k and 600k. Jan 10, 2008 · To minimize the leakage, those heaters are usually put near the grounded end of the heater string. (In the Mac it is unlikely that any audible effect will occur. And even if the tube does have that leakage, it may perform just fine in a later stage where signal levels are higher. Sometimes input stages can be very sensitive to leakage and the resulting hum. Jul 14, 2020 · Recently I been testing the valves in my Trio 9R-59DS, some of which must be approaching 50 years old and have seen a lot of use. Apr 3, 2015 · There really is little excuse for such leakage; I would regard the tube as unacceptable before going to the trouble of more elaborate measures. Some Bogen amplifiers run the 12AX7's off the DC voltage at the cathode of the power output tubes, a clever way to get DC on the heaters. I also tested pulls from the set and spares for it. Mar 1, 2009 · Getting some hum in a recent design, I hooked up a circuit to test for cathode-heater leakage for either triode or pentode, and got the shock that few tubes are 'kosher' in this department. May 14, 2020 · Thank you for the thoughts but there is no ripple on my heater supply to leak to the cathode and cause hum. I could hook the heater supply directly to the cathode and it would not cause hum. yaxp jkxuf qzvybb kpwcfwe jgbi cxov dkqnt mhc usfr ste