20-07-2020, 04:02 PM
(This post was last modified: 20-07-2020, 04:03 PM by Mike Watterson.)
As expected from visually examining the four coils:
Rear view of switches.
OC1 OC2 MW LW
The OC2 is maybe about 5.5MHz to 7.5MHz, perhaps a little less, I'd call that SW1!
The OC2 is about 7MHz to 14MHz, I'd call that SW2!
Rear view, 2nd coil from left is indeed MW LO as suspected, even though it's at the OC2 switch. Loads of LO on pin 3, g2, the pseudo anode of the Local Oscillator section. Nothing on the other switch positions. However driving input hard revealed:
1st Coil affects OC1 and OC2, as suspected.
2nd Coil is MW
3rd Coil affects LW.
4th does nothing.
So I'm thinking there HAS to be an RF in coil for SW. It's the 4th coil at the LW switch, because it needs to be as far as possible from the SW LO coil.
Next I make a discovery by accident. I had a 2.5m wire on the wire that originally went to the telescopic whip. I removed as I wanted to connect signal generator there. OC2 LO came to life. Even holding the insulation kills the LO. I connect signal generator by 47K to it and that works. As expected the 4th coil peaks the RF in OK at about 6.5MHz with tuning set open and first coil, at OC1 switch set for 6.5 MHz.
The coils behind the switch now make sense. Padding the two coils with SM caps can certainly change 40m to 20m (OC1 approximate coverage) to about 49m to 40m.
Now, is there a shorted cap, a short, open or faulty switch preventing OC1 and LW running properly and causing aerial wire to "kill" LO? It's progress, but the symptoms can't be fully explained by faulty switches?
Rear view of switches.
OC1 OC2 MW LW
The OC2 is maybe about 5.5MHz to 7.5MHz, perhaps a little less, I'd call that SW1!
The OC2 is about 7MHz to 14MHz, I'd call that SW2!
Rear view, 2nd coil from left is indeed MW LO as suspected, even though it's at the OC2 switch. Loads of LO on pin 3, g2, the pseudo anode of the Local Oscillator section. Nothing on the other switch positions. However driving input hard revealed:
1st Coil affects OC1 and OC2, as suspected.
2nd Coil is MW
3rd Coil affects LW.
4th does nothing.
So I'm thinking there HAS to be an RF in coil for SW. It's the 4th coil at the LW switch, because it needs to be as far as possible from the SW LO coil.
Next I make a discovery by accident. I had a 2.5m wire on the wire that originally went to the telescopic whip. I removed as I wanted to connect signal generator there. OC2 LO came to life. Even holding the insulation kills the LO. I connect signal generator by 47K to it and that works. As expected the 4th coil peaks the RF in OK at about 6.5MHz with tuning set open and first coil, at OC1 switch set for 6.5 MHz.
The coils behind the switch now make sense. Padding the two coils with SM caps can certainly change 40m to 20m (OC1 approximate coverage) to about 49m to 40m.
Now, is there a shorted cap, a short, open or faulty switch preventing OC1 and LW running properly and causing aerial wire to "kill" LO? It's progress, but the symptoms can't be fully explained by faulty switches?
