07-22-2018, 06:55 PM
Improvements!
First of all, with the changes back to mica caps in the IF circuit it was possible to get the IF tuned up with much more ease. However, I was still faced with an inability to align the 31 m spread band, so started looking at the caps in the oscillator circuit, as there is a lot of padding and trimming done to achieve the narrow oscillator tuning range (with repect to frequency). Eventually I found a 120 mmF mica that was suspect in value, so substituted a new cap. Success! I was able to adjust the osc. trimmer and get the 9.5 Mc/s signal rocked in at the proper dial setting. Prior to this, I could only get close, with the trimmer at full capacity.
The capacitance meter helped here, I could determine the original 120 mmf cap was low, and was able to select a new cap from stock to be close in the required value. Now the circuit aligns with the trimmer roughly midway along it's travel.
I'm pleased with the improvements.
Edit: I forgot to mention that I also found time to look at the speaker. The outer edge of the cone had become detached from the frame, the rubber grommets accompanying the fasteners were hard and split, and there was no sign of a gasket. I re-glued the cone, and had some felt left over from working on the Philco 16X. When I had removed the speaker a while back, I noticed it was very poorly fastened in place - something else the original "restorer" had hacked together.
It is no wonder the friend who gave us the radio was disappointed. Aside from the casual electrical restoration and quick cabinet wipe over with shellac, the speaker was:
1) Coming unglued at the cone surround, rasping and slapping the speaker frame
2) Voice coil rubbing the pole pieces
3) Barely secured in the cabinet with no gasket to to the sound board
I'm aware of the sum that changed hands for this radio, which was high even for a top condition item. Some people have no scruples whatsoever.
Cheers
Ed
First of all, with the changes back to mica caps in the IF circuit it was possible to get the IF tuned up with much more ease. However, I was still faced with an inability to align the 31 m spread band, so started looking at the caps in the oscillator circuit, as there is a lot of padding and trimming done to achieve the narrow oscillator tuning range (with repect to frequency). Eventually I found a 120 mmF mica that was suspect in value, so substituted a new cap. Success! I was able to adjust the osc. trimmer and get the 9.5 Mc/s signal rocked in at the proper dial setting. Prior to this, I could only get close, with the trimmer at full capacity.
The capacitance meter helped here, I could determine the original 120 mmf cap was low, and was able to select a new cap from stock to be close in the required value. Now the circuit aligns with the trimmer roughly midway along it's travel.
I'm pleased with the improvements.
Edit: I forgot to mention that I also found time to look at the speaker. The outer edge of the cone had become detached from the frame, the rubber grommets accompanying the fasteners were hard and split, and there was no sign of a gasket. I re-glued the cone, and had some felt left over from working on the Philco 16X. When I had removed the speaker a while back, I noticed it was very poorly fastened in place - something else the original "restorer" had hacked together.
It is no wonder the friend who gave us the radio was disappointed. Aside from the casual electrical restoration and quick cabinet wipe over with shellac, the speaker was:
1) Coming unglued at the cone surround, rasping and slapping the speaker frame
2) Voice coil rubbing the pole pieces
3) Barely secured in the cabinet with no gasket to to the sound board
I'm aware of the sum that changed hands for this radio, which was high even for a top condition item. Some people have no scruples whatsoever.
Cheers
Ed
I don't hold with furniture that talks.