[Arran]

Bob;
I was thinking the same with that 150 ohm resistor, put a larger value replacement in it's place to compensate for a silicon diode, or pair of silicon diodes. I think that the forward drop is roughly .7 volts on a silicon diode, obviously more with two in series, I was told that the selenium ones had a 4 or 5 volt drop when they were new, not 75 years old, so adding extra resistance following the replacement rectifier is a good plan, even better when the resistor following it is a dodgy sand resistor. By the way sand resistors are wire wound resistors, but that sand coating didn't do very much to protect the wire, or the connections, from corrosion, and the one in my set is looking a little green on one end, even though it read 160 ohms when I tested it.
I misspoke about the paper caps, the small ones were not 200 vdc rated, they were 100 volt caps, I may have a go at restuffing but I don't think I have any .022 uf caps that are small enough to fit in the shells, which are maybe 3/16'' on the inside. I guess that Phillips decided to use 100 volt ones because of the low voltages involved, and because they were smaller to work with, likely cheaper as well. It's kind of a shame as the set is all original inside, right down to the tubes. Has anyone tried painting those yellow poly film caps? I was thinking of trying some cardboard straws for capacitor shells, if I could find some the right colour. They are no good as straws so maybe they should be put to more constructive use.
Regards
Arran

[radiorich]

Hello Bob,
What nice looking set it looks like a Emerson that I have you did great job with the two Electrolytic cans .

Sincerely Richard
P.S. Bob I sure miss those Mallory ones that were made they were thinner but I did buy some Illions Cap ones that seem to be very small compared to others .

[klondike98]

Thx Richard.
Arran, the 0.02 caps in mine are also 100v. As I mentioned the original paper tube is just a little smaller than the modern yellow caps. After warming the tube and pulling the guts out, a slit down the side of the tube with an exacto knife allows you to open it up just enough to slide the cap in. With the slit placed out of sight you can’t tell it’s been slit.

[klondike98]

I can't believe I missed this little critter when replacing the electrolytics. Wasn't much of him left, he crumbled when I removed him.

[Image: https://www.dropbox.com/scl/fi/2vmm8o4lx...0x9b&raw=1]

I've gotten a couple more caps stuffed and have now started on what is likely the most difficult, C-5 and E-1. E-1 is a combination cap and choke that I have never seen before. I'm wondering if it's similar to those Philco caps that have the coil of wire wrapped around them although this one is fully connected into the circuit. Its simply listed as Choke and tubular capacitor (0.05uF, 200v). I won't know if I'll be able to reuse the choke portion until I get it out.

Question: Has anyone every replaced one of these? Is the choke a critical component or do folks just replace the 0.05uF portion?

[Image: https://www.dropbox.com/scl/fi/jtk0o26aw...rpkt&raw=1]

[Image: https://www.dropbox.com/scl/fi/fmy6p71xj...g78z&raw=1]

[img][/img]

[RodB]

That's the Philco rf trap in a foreign radio. Resonant somewhere around the IF, it's a short to ground. You can just replace it with the cap or wind about 8 turns of insulated 20 AWG wire around the new cap, being sure to connect them in series.

[radiorich]

Hello bob,
I have seen what rob is talking about done as a replacement for that capacitor choke combo.
Sincerely richard
P.S. that bug has been there for a long time I bet.

[klondike98]

OK, thanks guys. I thought that might be the case but wasn’t sure. It will be interesting to see what the internal of that component looks like.

[Arran]

Bob, Richard;
One more thing, I heard it suggested that it would not hurt to add a Zener diode between the start of the filament string, and ground. I have not tried this, but the filament string in most of these does add up to 7 volts, 8.4 volts in a set with an RF amplifier stage. How necessary it is I don't know, maybe useful in places where you have a lot of voltage spikes, or power surges, but it's not likely that someone would pull a tube and stick it back in whilst the set was still powered.
Regards
Arran

[Arran]

Bob;
I was looking through one of my RCC manuals tonight, the one for 1948-49, and guess what I found? There was another clone of the Motorola produced under the Rogers-Majestic brand called a model R109 "Take About", I think this has the best service info I have found yet: https://pacifictv.ca/schematics/rogersr109data.pdf
Regards
Arran

[klondike98]

Thanks for that info Arran. As it turns out rather than being very difficult (as I originally thought), removing the speaker to get access to some of these caps is very easy. One screw and one wire desolder. 

[Image: https://www.dropbox.com/scl/fi/b615ysed8...qzir&raw=1]

[klondike98]

I now have all the caps replaced. That combination choke and cap (E-1) was indeed just about 30 coils of 22 guage wire wrapped around a normal 0.05uF cap.

[Image: https://www.dropbox.com/scl/fi/7omuqw0jy...mwod&raw=1]

Since its completely buried in the chassis I simply wrapped it in electrical tape to keep the coil in place and protect against shorting. Now I'm waiting on an Antique Electronic Supply order for a power cord to wire in and then I'll add in the diode to replace the selenium rectifier.

[Image: https://www.dropbox.com/scl/fi/d132dooyv...j1uq&raw=1]

I did locate a fellow that has an image of the B Battery (Eveready 467) box that can be printed to create a reproduction battery from seven 9v batteries. It only gives you 63 volts or so but he says it should work ok. Here's the link to his page:
https://www.greenhillsgf.com/IndexOwn_63...eryKit.htm

I'll be working on that while I wait for the cord.

[RodB]

I've often wondered whether the capacitor foil adds to the inductance of the coil.

[Vlad95]

I did locate a fellow that has an image of the B Battery (Eveready 467) box that can be printed to create a reproduction battery from seven 9v batteries. 
Unfortunately this link may not available at nearest future.l 

There is huge number of battery labels on my site. You can find any for your needing and download free at any time.

Battery labels FTP

Now it is only FTP access for this part of datas, but at nearest future I planning to update this part of my site for normal access as all another resources.

[klondike98]

Thank you Vlad

[klondike98]

A bit more work on the Motorola. I got the repro battery together right up until I realized the snap clips on the top of the battery are larger than the ones we see today on 9v batteries. I'll have to look around for some. I used the file on vlad's site and then pasted the paper onto a manilla file folder. That seemed to be just about the right thickness for the box. Just be sure the image you print is the 7" x 10" that is noted on the file. That gives just the right size box.

[Image: https://www.dropbox.com/scl/fi/j7fs3kx30...bz4v&raw=1]
[Image: https://www.dropbox.com/scl/fi/cs38e4519...qxqr&raw=1]

I did wind up replacing the 160 ohm wirewound resistor with a 200 ohm wirewound 5 watt resistor. That gave just about the right voltage drop after substituting a 1N4007 diode into the circuit. The resistor does get pretty warm but the current flow seems about right 100mA with a 20v drop across the resistor. I'm getting 7.5v on pin 7 of the 3S4 tube (schematic calls for 7.9v) and 67v on the plate of 1R5 (nominal is 70v).

At this point I powered up the radio in AC power mode and was able to very faintly hear some stations but it is very weak and somewhat garbled. I did a quick check of alignment but that did not seem to be the issue so something else is going on. I will try power up with the A and B batteries rather than AC and see if that makes a difference. If not, I'll go back and recheck wiring and try some signal tracing through the radio.