23-07-2020, 02:27 PM
Rebuilt the tuning capacitor.
Important to draw the cord layout and know which of the three wires going to coil/switch pack are RF, LO and 0V.
1) Remove it, noting screw locations and a safe container to collect them. Remove drum first noting position fully meshed. This also has 2 x alloy spacers.
2) Remove the trimmer caps. Use a marker to indicate RF mica in case a different thickness. There is usually a metal washer, an insulating washer, sprung connection to stator and then the mica.
3) Unmesh fully and remove the rear lock and grub screw. There may be a ball bearing, this one did. Catch it!
4) Depress rotor spring and lift out rotor from rear catching the ball bearings at the front in a tub. Move the spring out of the way.
5) Clean the parts. Put on WD40, but it MUST be washed off later with alcohol.
6) Cut fine emery paper with a half circle to match rotor, for the stator. Use folded over, if need be add paper /card. On this one a folded emery/wet&dry was perfect.
7) Gently rub along rotation arc.
8) Use straight bit for the rotor
9) Clean everything with alcohol and blow it off.
10) Stick the front balls to shaft in the groove with pure BP petroleum jelly, which is cheaper than Vaseline which has additives. Remember one is for the rear. Put a dab in the rear depression of the shaft.
11)Drop in fully open, then fully mesh, gently, using pliers on the front shaft.
12) Depress and put slotted or holed spring behind rear shaft. You may need to jiggle rotor from front to get it straight.
13) Drop in the rear ball and add the grub screw. Centre the rotor plates in the stator plates.
14) Check using current limited PSU, beeper or DMM/Ohmmeter that there are no shorts on full travel on RF or LO sections. There weren't! But if there are, note position and redo from step (3).
15) Add lock nut and ensure grub screw doesn't move.
16) Clean the mica, insulated washers etc of trimmers. I replaced the steel washers as they were very rusty. Reassemble trimers.
17) Check again for shorts.
18) Remount and reconnect.
19) Re-string the pointer. You DID do a nice diagram? Ensure free running and not catching. Replace cord if in doubt of condition. The entire cord, wheels, drive shaft can be waxed, oiled or Vaseline coated. Replace spring, if needed, with a ballpoint pen spring if you have nothing better. I've used steel guitar string, the first that's not overwound, crab line, monofilament fishing line, beading thread and linen button thread on various sets.
It was perfect. No cracks/pops across any band.
Now, any experts? With a OC1 20m to 40m scale roughly marked with dashes, which of the two tuning points on SW is correct? They are of course 2 x IF apart. Which is why dual conversion was invented and why some military sets use 1.6 MHz or higher single conversion.
Next: Any better ideas than toothpaste to remove abrasion on some places on the scale?
Important to draw the cord layout and know which of the three wires going to coil/switch pack are RF, LO and 0V.
1) Remove it, noting screw locations and a safe container to collect them. Remove drum first noting position fully meshed. This also has 2 x alloy spacers.
2) Remove the trimmer caps. Use a marker to indicate RF mica in case a different thickness. There is usually a metal washer, an insulating washer, sprung connection to stator and then the mica.
3) Unmesh fully and remove the rear lock and grub screw. There may be a ball bearing, this one did. Catch it!
4) Depress rotor spring and lift out rotor from rear catching the ball bearings at the front in a tub. Move the spring out of the way.
5) Clean the parts. Put on WD40, but it MUST be washed off later with alcohol.
6) Cut fine emery paper with a half circle to match rotor, for the stator. Use folded over, if need be add paper /card. On this one a folded emery/wet&dry was perfect.
7) Gently rub along rotation arc.
8) Use straight bit for the rotor
9) Clean everything with alcohol and blow it off.
10) Stick the front balls to shaft in the groove with pure BP petroleum jelly, which is cheaper than Vaseline which has additives. Remember one is for the rear. Put a dab in the rear depression of the shaft.
11)Drop in fully open, then fully mesh, gently, using pliers on the front shaft.
12) Depress and put slotted or holed spring behind rear shaft. You may need to jiggle rotor from front to get it straight.
13) Drop in the rear ball and add the grub screw. Centre the rotor plates in the stator plates.
14) Check using current limited PSU, beeper or DMM/Ohmmeter that there are no shorts on full travel on RF or LO sections. There weren't! But if there are, note position and redo from step (3).
15) Add lock nut and ensure grub screw doesn't move.
16) Clean the mica, insulated washers etc of trimmers. I replaced the steel washers as they were very rusty. Reassemble trimers.
17) Check again for shorts.
18) Remount and reconnect.
19) Re-string the pointer. You DID do a nice diagram? Ensure free running and not catching. Replace cord if in doubt of condition. The entire cord, wheels, drive shaft can be waxed, oiled or Vaseline coated. Replace spring, if needed, with a ballpoint pen spring if you have nothing better. I've used steel guitar string, the first that's not overwound, crab line, monofilament fishing line, beading thread and linen button thread on various sets.
It was perfect. No cracks/pops across any band.
Now, any experts? With a OC1 20m to 40m scale roughly marked with dashes, which of the two tuning points on SW is correct? They are of course 2 x IF apart. Which is why dual conversion was invented and why some military sets use 1.6 MHz or higher single conversion.
Next: Any better ideas than toothpaste to remove abrasion on some places on the scale?
