hi truckernix, it isn't too difficult, as long as you make it look close to what it was like, it will be fine, because later when we go through the alignment procedures any small variation in the coil winding will be calibrated out.
in the photo of the dirty coils in the vise, the center outer portion is dropped down a bit, and touching it i could see it was sloppy loose which is no good on rough roads to the listener a weak station could have loudness variations with truck motion as this coil giggles, but it would likely not move enough in one instance to notice, really it just needed to be fixed on principle
the circuit of what this coil does is attached as well - the two halves are for the variable oscillator that modulate the selected band to the IF frequency. the oscillator must be able to span frequency ranges of (535KHx - 262Khz) to (1605KHz - 262KHz), that's 273KHz - 1343KHz to keep the range overlapping properly with the selected station, the span offset is taken up by adjusting the iron core positions relative to each other it's a pretty neat Rube Goldberg machine, but it works repeatably.
once removed from the rubber holder grommet, i slipped the coil apart into it's two halves, the inner one is a solid winding 1 layer thick end to end, i only had to re-wrap about a half dozen turns at each end and then held it in place with painters tape while the wax was warming up the outer half i tried preserving the coil but soon it all fell apart, since it's only 15 - 1/4 turns of evenly spaced wire, i decided pulling it all off and re-wrapping it was easier than trying to re-melt the gyptal in place, the spacing is not super critical as long as nothing moves when we are done that's what's important if one wrap is closer or father apart it will have virtually no significance to the desired mutual inductance of the inner-outer coils because the gap is so large between the two and it's an air core.
i taped the wire at one end close to where it was at before (you could see a shadow of the old wire on the core) then i rolled it on the table top, 15 turns happens fast, so go slow and even then tape the other end up. put a dab of wax here and there to hold it all together then i followed up with a bit of rubber cement in a strip along the wax (not shown) and finally used a hot air gun to remelt the wax evenly once the rubber cement strip was holding
wax is a good intermediate holding solution because it's very easy to undo if something goes wrong before you commit with the rubber cement -s
update still waiting on the plating shop, so in the mean while, here are some photos of the tuning clutch getting a new rubber pad for this task i used part of an inner tube, sanded it smooth then glued it to the assembly with contact cement, you can't use rubber cement for this task (i tried), rubber cement only seems to work when it's rubber to rubber, it peels off the aluminum very clean and easy contact cement seems to hold more like original
the clutch serves two purposes in the tuning assembly, one is to allow the tuning knob to slip if you try to turn it past the end of the mechanism limits, the knob is worm gear driven so you would have insufficient feedback before things got a lot of forces applied the second purpose is that it has a dis-engagement lever used when any of the tuning buttons are depressed, the first part of travel of a button opens the clutch before the final travel meets with two parallel rods to swing the tuning core guide bar.
for interest sake i included a photo of three button assemblies side by side with with different parts of the AM band programmed into them this is where the "memory" of a tuned station is stored in the radio these buttons have both ends and the center of the AM band stored via the half round disk that can swing to any angle. when a button is pulled out, that tiny disk can float free, as you push it back in, it hugs the two parallel tuning bars that rotate around a mid point the disk rotates to match the position of the two parallel bars perfectly as you press the button back in for programming, then on final travel of the programming action a lever pinches this half disk to clamp it firmly into position to remember the station.
Hi truckernix, yes if someone wants to save the info or make an article out if it that’s fine by me, I think that would be neat. I’ll answer any questions the best I can, also I’ll take advice too, i know I’m not going for perfection most days, but I’m trying the best I can with the motivation I got. -s
finally got some parts back from the hot dip galvanizing the original zinc was likely electroplated on, but i decided to take a risk and see how hot dip would turn out on some thicker steel parts
the zinc is quite thick in some places, i have spare parts of most of these pieces so later i can rework them and decide which way to go the hot dip process is a bit rough on the smallest parts, i see it did damage the light reflector part, fortunately it is not the one from the radio it was a spare that i was ready to sacrifice for the cause... so now i know better
there may not be updates for a little while now, got to make progress on spring outdoor things but i will return to it, feel free to send questions as usual -s
I was away for a while working on other projects, but i did make a bit of progress on the radio. while being near the gas welder, i fixed the radio housing. i wanted to see if i could weld it reasonably okay without totally destroying it. now that i have something that might be usable i'll spend time cleaning it up, i'll likely fill in the remaining imperfections with epoxy.
attached photos of the rusted / broken dimples that hold one end of the housing together notice one slot was stamped a bit too close to the edge and rotted open i managed to make a new dimples and welded patches with fresh dimples in, the radio housing is 0.040 thick, i couldn't find material in that thickness in all my junk, so 0.035 got used.
this weld mess of mine can always be cut out and redone if a better radio housing cannot be located in the future it will be our secret for now -s
Here is the latest progress. I have been taking advantage of summer to do outdoor things, haven't given up on the radio.
I put the tuner unit back together yesterday and today. Overall my method is: take it apart as much as i can, clean everything up, re-assemble with as many original parts as possible but don't go overboard using old parts if they are not good enough.
So turns out that hot zinc dip was probably not the best idea. Many threaded holes and tight clearances needed to be cleaned up to fit, that took a lot of time with files and sand paper and thread chasers. The movement should operate easily without any oil when all the parts are clean. Once it's together you do oil it and then it really gets smooth.
There was a lot of taking it apart to re-assemble in a different order. I should have made a few more notes about the disassembly order.
I am posting only photos from the successful order-of-assembly path. This means i have a fewer images to share, but on the plus side, when you look at any of my photos you will see a partially assembled state that should not require any disassembly if you reproduce that specific state during your work.
Attached photos: - tuner unit chassis - how to compare button return springs, I discovered that the earliest versions of this radio used substantially weaker button return springs. - weak spring vs newer stiffer spring, my springs got mixed up, but putting them back to back we can clearly see a difference in compression. - installing the buttons, us an alligator clip to temporarily hold them in place - all buttons installed
The button retaining part had a soft rubber strip on it that cushions the buttons return and prevents rattling on metal. I have replaced it with adhesive felt. It is a bit difficult to see in the photo, but there is a felt on both edges of that retaining part that the buttons extend through.
When using non-automotive grade self adhesive felt, i go around the edges with a dab of crazy glue to ensure the low quality adhesive won't let go.
second post with more pictures to follow shortly -s
- coils with iron cores installed - soldering the antenna wire braid back like it was, half on the chassis and half on the coil can - the old wires used as reference when making new wire bundles - soldering the power wire braid onto the tuner unit, this is also where the dial indicator ground wire solders, it seems redundant but the radio originally has this ground wire. - complete tuner unit with all new wire bundles ready to go.
hope i can get back to the radio sooner next time, next thing i'll work on is the dial face. -s
update painted some of the dial face parts, there are a surprising many bits to just the dial face on these radios some of the parts were two colors, black to minimize light leakage and the dial face color sorta sandy tan i use the closest colors from rustoleum brand spray that match the old paint alright, i'm not sure if the remaining paint is even the correct color after 70 years, as long as colors go well together and it looks good to my eye is what i care about right now.
to top indented edge of the clear dial face is white to reflect light around the top edge down onto the numbers, it acts like a 90 degree light pipe a bit. reproduction dial faces do not come painted, and their numbers are just a low quality sticker so they won't even light up 3D like an original. -s