[jjfritz5528]

   
I started the restoration of this radio a couple days ago. And after spending a while researching exactly what version I had (Many thanks to the Website Library!) I checked all the coils for continuity and discovered the lower section of the Primary on the Antenna coil is open and the Primary on the 2nd IF.
I have the Antenna Coil prepared to wind, just waiting for the proper gauge wire to arrive from Remington. This should be an easy fix, and also confirmation in the Library on the details on this coil.
The IF Coil may be more of a problem. It is the Primary winding on the 2nd IF transformer. The coil at the bottom in the picture. It is Item #25 on the Parts List in the Library for this Version (Run) of the 60B. Part #32-1050. It has stamped on the top center an "A7", if that has any significance, along with a "L1" on the Ground Bracket and some yellow paint on the Top (Wire side) of the unit.
I haven't seen any information on the wire size or number of turns for this, and also not sure my winding expertise is up to the task for this one! Are suitable replacements available for these? The Compensating Condensers are mounted separately. The 1st IF does have a different Part Number (32-1049) and is obviously different based on the coil resistance shown on the schematic.
I'm a bit hesitant to try to locate the same part, as it is widely known these have a high rate of failure.
SO I'm looking to the experts to provide some guidance on how to remedy the open coil, or obtain a suitable replacement.
Otherwise this should be a fairly straightforward Restore - Replace all the Block caps, Electrolytics, verify the Mica Caps and resistors, expecting many of the resistors to be out-of-spec. Some new washers under the tuning cap and a replacement tuning dial from RadioDaze.
Thanks in advance for any information!

[Radioroslyn]

Generally IF transformers are somewhat generic in broadcast sets. The major considerations are impedance, frequency, bandwidth, 
and physical size. The impedances between the input and output transformers are different. Going from the plate of the mixer to 
the grid of the IF amp tube is going from a somewhat low impedance to a high impedance grid. The output transformer is a bit 
different. It's matching and plate to the diode plate which is low impedance. I mention this because the the input vs the output
transformers do not make a good swap.

The frequency of the transformer needs to be tunable to the proper frequency. If by using the original tuning system or the
slugs/caps that are internal.

The bandwidth is mostly determined by the distance between the two winding in the transformer. For the bcb something around
8 to 10kc is a good width, for HiFi 15kc but on am there is no more HiFi.

Size can be whatever you can fit inside to old part and make it work.

Philco used 460kc IF transformers from '32-'36. I don't think that they have a high failure rate. The rf and ant coil do but IFT is an occasional problem on the sets I've worked on. They made a lot of those IFT's. I don't think it's a good idea to rewind it.

If you were desperate you could use a 455kc Ktran output IFT and retune it to 460kc.

[jjfritz5528]

Terry -
Thanks for the background information!
At this point I'm planning to melt off the wax and see if I would be lucky enough to find the break at the beginning.
SO one thought that came up was - could I take the Primary of another, 1st or 2nd IF from a Model 60, cut it off and glue it, to replace mine? The Primary resistance is the same on both, but I don't know if position, diameter, etc. are the same.
If that isn't a good choice, I will place an ad to see if I can find one from a parts set or junk box somewhere. This isn't something I have laying around.
Learning more every day!

[jjfritz5528]

Well, I melted the wax off the bottom, open winding and both leads were firmly attached to the solder posts. I unwound several wraps, from the outside of the coil, no breaks. The other wire goes down inside the back of the coil and I can't unwind any, unless I try to force the bobbin off the wooden center post. I did try a little, but if I continue I think it will destroy the wraps. So I think you can look for a Wanted ad posting in the near future?

[jjfritz5528]

Here's an update!
I unwrapped several more wraps on the outside, and I SAW the telltale blue-green corrosion color, and there was the break!! Very good news, and I am hoping that maybe 8- wraps less on the coil will not make any difference.
Now the difficult part. The other end , at the back of the coil only has a little over 1/8" of the wire exposed. I'm sure if I try to pull anymore, it will just break off with nothing exposed. So I need to try to solder the wire from the coil terminal to this short little stub. I am using magnifying glasses to see this. So hopefully tomorrow I will attempt to solder. I do have the insulation off it, but it sure is short.
I had done some poking around with a pin to try to find the break, when I decided to just unwind more, which certainly was good!

[Chas]

Keep a count of the total number of turns removed... Should a replacement not be found and the coil fails from too many turns removed. FWIW a splice and replicating the turns with the same wire size will work. If not, the coil could be rewound, I assume it is universally wound ( winding waves back and forth) and with a single strand of wire? Does the wire appear to have a couple of threads wrapped around it?

Ideally, all information to rewind is in the coil itself, wire size (type) turns direction, position, width. Duplicate and it will work.

Chas

WA1JFD

[Radioroslyn]

Sounds great! Just remember if you have trouble getting it tune you can always add a little C to replace some missing L.

GL

[morzh]

If this IS the 2nd IF coild and IT IS the secondary, you do not need to worry about 8 turns removed and splicing.

Technique:

Use a bit thicker gague (not much thicker) wire than the one use in the coil.
Alternative: use a real rigid wire (like a lead from a resistor/cap).
Prep the stub (clean/tin).
Measure the length so when bent, it touches both the lead and the wire stub.
If using magnet wire, prep both ends.
Solder well your wire to the pin.
Route the wire to your stub. If rigid, make outward right angle, push towards the stub so it stays touching it, then solder. If it is a thinner magnetr wire, route along the coil, then solder, then put some wah over.

[RodB]

Yes, Mike, I've used that technique many times. I've never had a problem doing this. All you have to do is bring the coil stub in contact with the wire lead and touch gently with the soldering iron that has a small drop of solder. If possible, use a touch of resin.