[bruderhaus]

Thank you for letting me join the forum. I have a love affair for the Philco 37-650, as it is the radio I grew up with. My twin brother and I would listen to Big Jon and Sparkie while my father would listen to Jack Benny. We would scan the newspaper radio schedule listings to see when special programs (like “No School Today”) would come on and then set our wind up alarm clock so we would not miss anything.  Alas, the 37-650 faded in oblivion as newer radios and TVs came more common but the memories never faded. The 37-650 grew old and sick and sat unused for decades.  It is now time for me to bring it back to life.

I am an amateur in electronics and try to learn more every day. I have read just about every article on the web about the 37-650 and am now about to attempt restoration. I hope lovers of this particular model will be able to continue to aid me in my quest.
In my exploration I have found that the chassis is 95% original and a few repairs appear to have been made, perhaps in the 1950’s. Visual inspection showed no burnt, melted or otherwise damaged parts. All the capacitors appear to be original Philco brand save for one. 
My initial test was to check for any shorts; this was done with a check of the windings of the transformer then a careful “power up” with a light bulb in series with the AC input. To my surprise nothing blew up or caught on fire!.  Local AM stations came in though faint. There was a 120 cycle hum (not unbearably loud but annoying.) The indicator lights were not functioning so I bought some new bulbs and repaired the light sockets for the dial and shadow meter.  I also purchased a tunable loop antenna (tecunAN-200) and, as the radio was in my 1929 one car garage, I made a local “earth ground” by tapping into an old 1 inch water pipe I could see thru a two inch crack in the concrete floor.
Next issue was to determine the antenna connections for the new loop; I finally decided to (after cleaning the terminals) to place the loop on terminal 1   with the jump connector tying in terminals 2 and 3. The shield wire from the tunable loop was placed on terminal two. My new “earth” ground wire went to terminal three.    I removed the chassis from the cabinet and placed it on a small table just behind the cabinet, in this way I could leave the speaker attached, the shadow meter was given a new front cover from the bottom of a frosted pill bottle and then placed in a plastic tray where I could see it. I placed tin foil around part of the bulb as the original metal casing around the bulb was missing. After lightly cleaning the chassis for dust and dirt, I was ready to test. (I am working on a 44 special bullet casing to make a new brass cover for the bulb.)
Surprise but the radio and shadow meter worked, at least partially. The shadow meter moves but not as “fine” as it should. On the band one the stations came in clear but mildly distorted. By adjusting the loop antenna dial I could get right onto the stations and they came in strongly. The radio dial was fairly accurate but not perfect. I could not find Big Jon and Sparkie L.  Bands two and three were dead except for 120 cycle hum.
The volume switch seemed to be working but had a few scratchy parts. The On Off switch for tone control was a different story. When the radio was turned on and in position one, the sound was very weak; in position two the sound was very bright; in position three the sound was bright; and in position four the sound was muffled. This told me that, if the tubes are not bad, then many capacitors will have to be replaced immediately.  
 
 
The only non Philco part appears to be a replacement of Bakelite capacitor part # 54 &54A, the Bakelite double (3615-YU) had been replaced with a Philco Bakelite single capacitor (8326 SU) and an external “American Capacitor”  .3 (?) mF  in a cardboard box.    The tuning section may have been removed and worked on at one time as a wire from chassis (6JFG base) had been cut and then repaired, repaired with very old cloth electrical tape. The tuning section front section (for part #20 oscillator transformer) has what appears to be a replaced part as it is white while the others are brownish (aged?) in color. There is also a bend in the metal of the tuning box in one section.  
My initial plan is to replace (restore) all the Bakelite capacitors and tubular paper capacitors with mylar film ones if feasible, however they would be replaced one by one and the radio tested after each replacement.  The aluminum can capacitors would be restored by opening the cans and using radial Mylar capacitors, if feasible. In that the aluminum can capacitors are primarily for the power supply, these should be the first to be restored. In that the tuning section will be the most difficult, this would be done last as the one section for broadcast band appears to be working correctly (why fix something that is working?). I would like to use capacitors that are between 20% to 30% over the originals and to have a WV of at least the original specification if not slightly higher.
My test equipment is very sparse at the moment. I have a digital multimeter and am attempting to restore an analog Triplett model 2400 (from 1946). My initial tests on the Triplett 2400, after replacing the leads with new wires and using a small 22 ½ volt battery, appear promising.  The 2400 was given to me and appears very clean inside, the ohms part is the only part I have tested so far. My Tek oscilloscope is currently not working and I may have to do without it for a while.
My questions to the group are:
1)     Does the order in which I want to restore it seem appropriate?
2)     Is Mylar a good substitute for the Bakelite and tubular electrolytic condensers?
3)     Is there anything I need to be super cautious about?
4)     Are there any resisters that I should automatically change
5)     Any other suggestions?
I have attached some pictures, I hope they make thru the web  . They are not great pictures but will give an idea about the chassis.
Thanks for any and all assistance.


I guess I don't know how to insert an image, :-((