Ray Robinson has a the story of the AR7 receiver on his web site, well worth reading
I have two of these receivers and both have been modified by "Harry the Ham" in the past. Both have had most resistors and capacitors replaced during the 1960's just before I was given them. The first one here is almost original except for the first RF amplifier which has been changed to an EF50 valve. My guess is that will make the receiver unstable so I should change that back to a 6U7 when I restore it. It also still has the original 12V DC / 240V AC power supply with it.
The second one has had the original output transformer removed and a 240V AC power supply built in. Looking under the chassis you can see the tiny O/P transformer and the filter chokes and the electrolytic capacitors that were in the external power supply. The 6G8 valve has been replaced with a 6SN7 and there is also a voltage regulator tube in a 7 pin novel socket and another hole for a 7 pin socket that means this is probably an unfinished project. There is also a 6H6 valve in place of one of the other tubes and I will have to trace the circuit for other modifications.
The power supply is untouched and will have to be revived that very carefully.
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Written by and Copyright, Phil. Storr © Last updated 16th September 2013