[gprutchick]

I have rewound the secondary of the Range 1 ANT coil using Litz wire. The AWG of the Litz wire was a bit different in that the final coil resistance was about 4.3 ohms, the inductance was 185uH. I did the calcs and this inductance is good given the range of the tuning capacitor which is 15pf to 420pf. The IF is aligned and crisp. The RF alignment is good. Known local stations are received at the correct dial setting. The 6A8 osc is strong, the osc grid ranges from -14.2V at the low end of the dial and -11.3V at the upper end.

Unfortunately the sensitivity of the radio has not changed. So, I rewound the primary of the Range 1 coil. It did not change the sensitivity. I substituted 8 different 6A8 osc tubes with no change. Since the Range 1 ANT signal passes through the secondary of the Range 2 ANT coil I tried to short the Range 2 secondary thinking it was the culprit, but no change.

There doesn't seem to be much coupling between the pri and sec of the Range 1 ANT coil. Touch the cap of the 6A8 and the radio works fine.

I checked the AVC voltage using an RF signal generator as the antenna signal source. With no signal the AVC is around -2.2V. With a fairly strong signal, it gets up to around -11V with the dial at 1500 and -14V with dial at 550. I think I can conclude the AVC is working ?

NOW WHAT? I still think the Range 1 coil is the problem, but I just don't know how to solve it. How do you improve the coupling of an ANT coil, which is wound on an air core. I don't have much experience winding coils.

I just discovered something that I think is strange. I was monitoring the antenna input signal with my scope when I did the AVC check. I disconnected the RF generator, the scope was still connected to the ANT terminal. When I switched to the SW band, there was a significant amplitude of a sine wave, close to the frequency selected by the dial. Is this normal? I don't see how this can be unless I made an error during the electrical restoration. I double checked everything, but ?

I have put many hours into this one. Maybe I need to put it aside for a while?