wa2ise
Super Member
Merry Xmas everyone.
(My Xmas party outfit) After the Xmas activities, I decided to see if I could merge an old Pilot tuner T601 my father bought back around 1950, and a Motorola add on MPX HS996A console MPX stereo decoder. First I had to replace most of the paper and electrolytic caps, and I used a bridge rectifer in place of the single ended selenium that was there (this feeds 120Hz pulse DC to the filters, and avoids DC saturation to the power transformer, which may let me get away with the extra loading from the MPX unit on the transformer, it's not getting too hot). The MPX decoder has no power supply, so I tapped the Pilot's. The MPX unit used a neon bulb to light up to indicate stereo reception, but the avaliable B+ wasn't high enough, so I substituted a white LED from a string of Xmas lights. That drops 3V instead of 67V, so the 19KHz amp and/or 38KHz doubler tube can function, as this LED is in its plate circuit. The presense of a stereo pilot signal makes the tube draw more current, making the LED light up brighter.
This shows that MPX units are not at all fussy about what tuner is driving them.
This shows that MPX units are not at all fussy about what tuner is driving them.