Quote:
Originally Posted by Tubejunke
Good info! Especially as I thought that the 1LA6 was a direct substitute via a 7 pin min. to loctal adapter. Didn't hear of a capacitance change. My point hidden in my long winded post was to find out why 1L6s of low to almost no emissions work great in 2 different radios and tested on two different testers.
I don't have any 1L6 that actually tests good, but have two radios that work really well. Very sensitive radios that pick up stations that I don't even think about on the average radio. Again, the only 1L6 that I have that doesn't work has no readable emissions. I haven't seen any footnotes in test setup sheets indicating good under a lowered range such as I do on certain old loctal tubes like the 1LN5 which states good over 30 which is very low on the scale
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Some circuits simply don't care as much as your tube tester does how good a tube is. I've had a number of radios that would work decently on weak tubes.
A converter tube is acting more as an oscilator/mixer stage than a gain stage (mixer tubes generally are not a high gain stage relatively speaking IIRC). The big gain occurs in the IF and to a lesser extent the RF on sets with a RF stage. The AVC likely compensates for the low gain of a weak tube by cranking up the amplification factor of the other tubes it controls.... Where you may notice a performance difference, if you get a good 1L6, is on stations (on a band NOT swamped with RF noise) that with the volume maxed are BARELY loud enough to hear (in this case the AVC is running all tubes at max gain so sensitivity is based primarily on tube health). Those stations will come in louder with a better tube or become unreceivable with a swap to a weaker one.