Quote:
Originally Posted by Kingfisher
Mine has a bad hum, part of the circuit board near the output tubes looked fried. I haven't used it in several years. This must have been one of the last tube models Arvin made since it was bought new in '68. Won't be finding any 50HK6 tubes at Rat Shack. They stopped selling that kind of stuff loooong ago.  Arvin was known for wierd tube numbers, 50HK6, 20EZ7, etc. It's often a dead giveaway as to who actually made some store branded radios. |
I remember the 20EZ7 tubes, luckily I didn't lose them! I think they are a 100 ma. heater version of a 12AX7. There are two filament strings in this radio, one with the IF, AM convertor and multiplex tubes which uses the 100ma filament tubes (18FY6, 18FX6, etc.)
and the other filament string which has the 150 ma. filament tubes (50HK6, 50C5 and 12DT8 plus a resistor).
I didn't learn till fairly recently that the 50HK6 has part of its filament as a fusible resistor for the silicon diode B+ supply (I know in other radios this is how the 50HK6 is used and presumably in this one too). I never could figure out as a kid why putting in 2 50C5's caused there to be no power.
Even in 1984 although Radio Shack did have a tube tester and tubes in stock they still had to special order the 50HK6 tube for me.