20-06-2020, 07:22 AM
No it's not Peter!!
Started to try to do a tracking alignment with the shabby MW aerial. The set was very unhappy with the repair showing signs of being unstable, breaking into oscillation unless there was a strong received signal.
I dug up the capacitor that I removed last, (looks like two thin oblongs of paxolin sandwiched together with rivets at either end, there were others similar in the set), and tested it again, it again read way high, 95pF
should be 20....
It has no markings except a blue paint spot.
One end of the capacitor was connected to the tag on the under chassis side of the oscillator gang with a wire leading to the oscillator coil. The other side was connected to #1 and 2 tags on the octal socket of V2, (the metalizing/internal screen? Pin [1] ).
NB. The valve in V2 position in this set is a short 1N5GT that has no external metalizing.
I shorted pin 1 to pin 7 (filament -) so that the 20pF capacitor and V2 screen are now at signal ground.
The set is now well behaved and tracks up quite reasonably too....
As Mike suggested that this set had an octal conversion I wonder if the capacitor was misplaced then, or, if the set has always been crippled, and that the capacitor didn't go faulty it is plain just the wrong one fitted in the first place ? If it had been connected correctly, the radio couldn't have worked at all.
Hopefully it is now history!
Amie.
Started to try to do a tracking alignment with the shabby MW aerial. The set was very unhappy with the repair showing signs of being unstable, breaking into oscillation unless there was a strong received signal.
I dug up the capacitor that I removed last, (looks like two thin oblongs of paxolin sandwiched together with rivets at either end, there were others similar in the set), and tested it again, it again read way high, 95pF
should be 20....It has no markings except a blue paint spot.
One end of the capacitor was connected to the tag on the under chassis side of the oscillator gang with a wire leading to the oscillator coil. The other side was connected to #1 and 2 tags on the octal socket of V2, (the metalizing/internal screen? Pin [1] ).
NB. The valve in V2 position in this set is a short 1N5GT that has no external metalizing.
I shorted pin 1 to pin 7 (filament -) so that the 20pF capacitor and V2 screen are now at signal ground.
The set is now well behaved and tracks up quite reasonably too....
As Mike suggested that this set had an octal conversion I wonder if the capacitor was misplaced then, or, if the set has always been crippled, and that the capacitor didn't go faulty it is plain just the wrong one fitted in the first place ? If it had been connected correctly, the radio couldn't have worked at all.
Hopefully it is now history!
Amie.
