[Arran]

Philco liked using those Bakelite block capacitors across the power line for years, probably because it could do double duty as a convenient terminal strip for the power cord. I have heard that the potting in them is tougher to get out then the 1930s blocks, but not too hard.
Regards
Arran

[morzh]

They did change the tar type, more than once, and yes, the later ones are a bit tougher. Also flooded grommets they used for some time did not help
I am sure they were re-using old stock in the later radios.

[radiorich]

Hello Arran
yes, I am sure that is one the reasons they kept using that item way past it's prime ,
If it works why change it !

Sincerely Richard

[jrblasde]

Does anyone know what kind of paper is used to line IF cans? There is a tube of paper inside all three IF cans on this radio, and it is preventing me from removing the internals. I had to sacrifice the paper to remove the internals.

To replace it, can I use regular paper or will I need insulating paper?

[jrblasde]

Here’s the paper I am talking about. Seems to be glued into the can.

   

   

[jrblasde]

Disregard, I found an answer. As I suspected, that paper is placed around the innerworkings to insulate them from unintentionally contacting the metal can (since that is grounded). Given that regular paper has an unspecific insulation rating, we can't say whether it will be adequate. It probably would be fine, but let's use insulating paper. I've discovered it is readily available on Amazon for roughly $12.

[morzh]

I was lucky and bought a large roll of fishpaper on eBay.
Fishpaper is the one to use.

[jrblasde]

Thank you, Mike. I will order the fish paper. I saw that on Amazon, and admired the odd name.

    I should provide an update on the project. This week was fairly busy with work, so I felt that I wasn't able to spend as much time working on the radio in the evenings. Nonetheless, I finished disassembling the main and the RF chassis. Those were some very tough rivets to drill out! I knew that it would get up to about 50 degrees on Wednesday, and then it was 61 degrees on Thursday. I read that it needs to be between 50 and 90 degrees to use naval jelly, so I rushed to get the two parts of the chassis ready to clean on Thursday. It was about 7:00 PM by the time I was ready on Thursday evening, and the temperature was cooling down and hovering right at 50 degrees. I got it done, though! I applied the jelly, let sit for 10 minutes, and then scrubbed it with steel wool. I let it sit for another 5 minutes, and then wiped it clean with a wet rag. There was still some remaining jelly, so I sprayed the chassis clean with a garden hose on my driveway.

    There was still just a bit of rust, so I applied a bit of baking soda and scrubbed it into the metal. One more rinse, and it was looking pretty good! There's a couple of remaining spots of rust, but they look more black in color to me (that is, they don't look like normal red rust).

   

   

    Aside from that, I have been cleaning up the components I'll be reusing (hardware, trim caps, the band wafer switch, the IF cans, etc.). There is an assembly of three trim capacitors named C404 A/B/C, and it is a Philco part number 31-6464. One of the three trimmers had a cracked housing. I was able to repair it with some super glue and a clamp. I then was able to reinsert it into the assembly and re-solder one side of it to the common frame. I made sure that it still adjusts (it does) and that it still appeared as an open circuit to DC.

   

   

   

    I used an LCR meter to start filling in some missing values on the schematic. C402A and C402B (both trimmer caps) both measure 10 pF. C404A and C404C measure 20pF, whereas C404B measures 600 pF (this unit is larger than the other two). As for inductors, L403, L406, L407, and L408 all measure 2.0 µH with a DC resistance of 0.1 Ω.

    Lastly, I've removed the cans from all three IF cans. I cleaned them up in an ultrasonic bath of hot vinegar. They are looking nice! I've cleaned all of the trimmer caps in them with some electrical contact cleaner, and I have measured and cut 9" leads of new 20 AWG stranded wire for them. I need to order new capacitors to replace a few mica capacitors in two of them (might as well, while they are open).

   

Lastly, I have finally disassembled the wafer switch. That is to say, I've removed all of the wires and passive devices connected to it. It's out in my garage, and I've been in the process of cleaning up all of the solder lugs so that it may be reused. I will also need to clean up the air gap tuning capacitor a bit, and then I'll reinstall it. But the chassis is now fully disassembled, is clean, and is looking pretty sharp with a few fresh rivets on it!

   

[radiorich]

Hello Joseph,
nice Job on your chassis and I too use fish paper "Fibroid Fish Paper Electrical Insulation" made by GC electronics .
Sincerely Richard

[jrblasde]

I've made a disappointing discovery this evening. That is, my 3rd IF can is a Meissner part #16-6660. This is not the original unit (I don't care about that part), but it is strictly an AM IF can (456 kHz intermediate frequency). That's not going to cut it for FM demodulation!

    I've already been down this road with my 49-906, but these Philco IF cans are impossible to find for the FM sets. Philco used 9.1 MHz as their FM intermediate frequency at the time, and that's a very unusual value. I'm going to have to build my own IF can, just as I did for the other set. But last time I built a 1st IF can, so this will be slightly different. This also appears to be quite the complex IF can to reproduce!

   

I suppose I'll search the internet to see if there happen to be any similar options available right now, but it may be time to put back on my PCB design hat!

[morzh]

Yeah...fun.