The AM Forum

Just a note that might help others, it seemed that the Ranger 1 I got along with my Desk KW was put under the hum curse sometime in its life.  The first source was user induced from the solid state relays I used to replace the damaged original plate relay in the Desk KW, the addition of RF chokes and bypass capacitors on the plate relay control lines removed the RF that was modulating the 240 VAC feed to the plate transformer.  After this all was well for a couple of months until a new hum source emerged, the clamper tube developed significant heater to cathode leakage and after changing that tube it sounded great for about a year before a new hum appeared on the carrier.  A quick listen in the receiver showed that the xtal sounded fine and the only hum was on the VFO signal.  I foolishly took the VFO cover off (not the easiest thing to do with Johnson gear) and replaced the 6AU6; after replacement the VFO still worked and so did the hum.  The source this time was the keyer tube which would have taken all of 30 seconds to replace had I thought about the problem before jumping into the VFO cover removal.  I finished the morning by doing the first fuel filter replacement in my '06 diesel pickup and due to design changes since I bought the same model in 2001 fuel filter replacement is now like replacing a tube in a Johnson VFO-I can't win!

Rodger WQ9E