[Geoff]

I'm working on my Philco 640 right now. I've tested all the coils and they are fine. Here are some of them:

[Image: http://antiqueradios.com/gallery/main.ph...alNumber=2]

I would like to clean them up a bit. I plan on using a soft artist brush to brush all of the dust off. This is not my first restoration so I know that some of these wires are very delicate so I will be careful. Once dusted, I was wondering if it would be OK to use isopropyl alcohol with a soft brush to clean them further. Something like this:

[Image: http://pugsandkisses.com/wp-content/uplo...st-P+K.jpg]

Or maybe spray them with electronic cleaner. Something like this:

[Image: http://www.frontiernet.net/~jcray/04F250...ing-07.JPG]

Philco coils are infamous for opening and I consider myself lucky that these ones are fine. To protect them going forward I was thinking that after I clean them I could coat them with connector coating:

[Image: http://antiqueradios.com/gallery/main.ph...alNumber=1]

Or possibly clear nail polish.

Assuming I am careful around the delicate wire leads, does anyone think that what I am proposing will cause any issues with the performance of the coils?

I would think it would be fine but wanted to get some feedback before moving forward.

Thanks,
Geoff

[Radioroslyn]

Personally I think your asking for trouble.
Terry

[Ron Ramirez]

I agree with Terry (Radioroslyn). My philosophy regarding coils is, if they are working and do not have the nitrocelluloid insulators between windings as with older Philco coils, then leave them alone.

[Chuck Schwark]

Like Ron said, +1.

[morzh]

I never clean coils.

If you see much cobweb there, you could use (VERY GENTLY) a canned air (duster), not strong, just to blow the debris away.
But no cleaning, no mechanical contact if possible, no brushing etc, and certainly no solvents or liquids.

But - clean the cans to your heart's content.

[David]

Please be very careful with the crc stuff it will destroy plastics rubber and other items right now. David

[PhilcoMike]

Ron,

Good point. What was the cutoff year for using nitrocelluloid insulators?

Thanks,

Mike

[Geoff]

Thanks for the feedback guys. I think I'll just gently blow air from my lungs to get as much dust off as possible and then leave them alone.

- Geoff

[morzh]

Do not kill spiders inside.
It's a bad luck.
relocate them to some remote corner of your attic.

[Arran]

Electronic contact cleaner is really just a blend of various alcohols, nothing really that exciting in it. I've washed coils before using a TSP and hot water solution. I did not scrub the coil or touch the leads, just dipped them, swished them around, and then dipped them in clean hot water to rinse. Then after it was air dried I remelted the wax with a heat gun, not enough to make it run but just to soften it and drive any moisture out. These were 175 kc If coils, absolutely filthy, and they are still working fine. I wash chassis with the same solution all the time, coils, IFs, and all, and never had any coil problems afterward, I just give them lost of time to dry out. You could spray those with alcohol, I can't see what harm it might do, the plastics are mostly phenolic based so the will not dissolve.
Regards
Arran

[Ron Ramirez]

What was the cutoff year for using nitrocelluloid insulators?

Technically, 1937 - the 37-84 was identical to the 84 except for cabinet and using octal tubes instead of the old standard base tubes. The 37-84's coils were identical to the 84, and also use the film insulation. The 37-84 was, I believe, the last to use coils with that bad insulation material between windings. None of the other 1937 models used that type of coil - Philco had switched to much smaller coils in most (if not all) other 1937 models.

Before that, the 38, 60, and 89 in the 1936 season were among the last to have coils constructed in this manner, as the large coils used in the 600 series of models, and the 116, are made differently and do not appear to have any nitrocelluloid insulation.

[Radioroslyn]

As an aside I have two model 600's that both have open osc coils. I don't think they have the insulator but both pri and sec are open. As Ron noted they are a smaller size and a pain to rewind.
http://philcoradio.com/phorum/showthread...=model+600
Terry

[PhilcoMike]

Thanks Ron. As always a walking Philco repository of information!

Mike