Rich;
So you did. One thing I like about Philco service materials is that they at least show part's placement, which makes them better then Rogers sets, neither are as good as RCA or Stromberg Carlson, those show the wires and how they are routed, connected, and so on.
Regards
Arran
I've started reading the books linked by @MrFixr55. And you're right, @morzh... they are very similar to MOSFETs. They run at a different voltage range and need a bit of heat. Even some of the schematic symbols we use today make a little more sense now. I haven't gotten into the underlying math of the components, but a pn junction diode and a vacuum tube diode conceptually operate under the same principle. The same thing with a Triode and a MOSFET.
I haven't looked this up, but I'm assuming that structures like current mirrors might not have been used with tubes. MOSFETS can be made small and cheaply while tubes take up space and would get pretty costly for large circuits. I'll probably find out more about this as I read. I do know there are some other tube types coming up that I haven't covered yet.
Anyway, back to the more relevant topic of the restore. I've decided to redo the cabinet. I do understand appeal of wanting to keep it with that "aged" look. I've cleaned the chassis and components as much as I can without removing things. The next step for the circuit is going to be to make a list of capacitors to order. Do you guys have a recommendation of where to get them? I've used some of the larger sites like Mouser but I figured you may know of another shop that has great prices. Is radiodaze.com a recommended site?
You will be surprised.
While current mirrors indeed are transistor-based curcuits, it is possible to create it using tubes (the curcuit will be somewhat different).
But SS current mirrors are used to improve upon tube curcuits.
Like, for an output pushpull, the CM could be use to equalize the idle currents of the two tubes, and such.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
You can find much of what you need from Mouser, though getting axial lead capacitors from there is more difficult, you can use radial caps inside the Bakelite block cases, they fit rather well, but axial ones will fit too. I myself gave bough caps from both Radio Daze, and WJOE Radio, WJOE radio is very reasonable if you want bulk film caps, they sell both axial and radial lead ones too, resistor selection is more limited then Mouser of course.
With regard to bulk however there was a series of tubes developed by RCA called "Nuvistors" they used them in TV tuners a lot, and there were also subminiature types, sometimes called "hearing Aid Tubes", the envelopes are the width of a pencil. The main selling point with transistors originally was that they used less power more so then less room, mostly because of not having a filament to heat. Some of the European and British portables show that size really wasn't the aim, they had multiple bands, and big speakers.
Transistors cost more though at the time because they were more expensive to manufacture, and had a high rejection rate, almost 1/2 didn't leave the factory for one reason or another. Some of the early Ratheon ones cost $15 each at retail in the mid 1950s, so needless to say tube portables were around for a few more years after that alongside the transistor sets, and much longer in AC powered devices like TV sets.
Regards
Arran
For me I find Mouser to be overly complicated for what we generally need to fix antique radios. For example, if you just put resistors in their search box it comes up with 16 different categories totaling over a million pieces. They are more for an engineer or manufacturer as they cover everything those people would need, it’s great for that. I find a source like www.justradios.com to be perfect for what we need. If you plan on sticking with this hobby, they even have kits of resistors and capacitors containing the most often used parts. They have a few different type of resistors and capacitors listed covering most of the values, voltages and wattages we need in an easier format to order from. If you need that one unique part Mouser does give you more choices.
Though Mouser search has its quirks (I in fact called them about one specific case of not finding a part yesterday), it does not occur to me as overly complicated.
I just limit the search and, say, if I need a resistor, I could quickly limit it to search, say (without even picking the category like "carbon / MELF" etc), such as below. Say, looking for axial 100K 2W 1%.
100K / axial. This limited my search to 800 instances.
2W - down to 70.
1% - 18 instances.
Done.
Now, with all results on one page, Yageo @ $0.177 at 10 pcs is my choice.
THis took me under 1 minute.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Like I said I agree if there is something unique or special, Mouser is a good choice. I’ve been on their site a couple times and ended up leaving because of how complicated the process seemed to me. Just radios or WJOE or others has what I generally use 99% of the time with using their easy chart with all values they offer and you just click on them, done. The only time I used Mouser was for a couple crystals I needed and couldn’t find anywhere else and that was a hassle to narrow down. For an engineer or manufacturer they are great as they have more variety and they do give a great description and specs of the components you’re interested in so in general I think that’s the customer base they are after.
All right. I have my capacitor list. I basically went down the part list and picked all the condensers that didn't say "mica" and visually inspecting that the cap is what I expected it to be (paper wrapped ...other than the electrolytics that is). Do you guys have a preferences for the type of capacitors you use? Can those paper wrapped capacitors be restuffed? I noticed a write-up talking about using Orange Drops but I'm not sure that's the way to go if you want to restuff.
How about tips on improving the look of the chassis and metal shields? I assume they are made out of steel. There is some rust in spots but I'd like to clean it all up and have it looking good again. Is it worth stripping everything out and cleaning? Recommended cleaning products? I'm not sure about the tuning capacitor either. I've cleaned it the best I can without removing it but it's still pretty rough looking.
I'm betting there are some good threads on here that probably already talk about some of this. I'll keep searching too.
OH! And another question. I need to replace the speaker, speaker wire and the power cable. Does someone make a 3 conductor cloth wrapped power cable? I assume I can connect the GND to the neutral of a 3 conductor plug. Or do you guys use a 2 conductor cable and run a separate wire to a grounding rod?
(This post was last modified: 12-15-2025, 05:26 PM by eewill.)
I use the metalized radial caps (yellow ones) from Just Radios. I don't restuff paper caps because I figure who is ever going to see that except me. Same for ecaps unless there is no room under the chassis. I do admire those that do.
For cleaning the chassis I always remove everything I can so I can do a good job cleaning. I stay away from liquids as they are a mess but do use naval jelly sparingly on rust. I use scotchbrite abrasive wheels on a dremel tool as shown in the picture.
As for the power cord. Using a 3 wire cord and connecting the ground to the neutral is not recommended. You might as well use a two wire power cord in that case. I use two wire cords. They can be found on Amazon. The ground clip for the antenna should go to a pipe driven in the ground. That is what I do. Makes a big difference in the amount of noise. Using the house ground may very well introduce more noise.
Quote: Well, I was planning on (eventually) putting the radio in my 3rd floor office at work. There is no way I'm getting a line down to a grounding rod.
The office will be problematic for RF noise, sorry. None the less the antenna can be as much wire that can be hidden and routed high on the wall. The ground can be a counterpoise similar length as the antenna wire routed along base board molding.
The AC plug can be used with a plug-in RF filter at the outlet. My not be of much help as the filter references the AC ground at 3 stories from earth there will be a lot of noise on the AC ground.
An alternative if you a blessed with your own window, is the use of a tunable external loop. Connect with separate wires no more the 6' to the radio do not cable these wires.
I tried for years to operate an AM radio in all of the electronics labs I had. Nuts, none worked well building was too shielded and noisy.
Nice work on the radio. I have had that model sitting in the"Q" for years. Someday I will get to it.
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
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