[titan1a]

Well I know now that 4 tubes are bad/marginal and one is an older sub (6C5) for a 6J5. With both output tubes bad I can understand high distortion.

Permit me my folly to ask an old but perhaps stupid question: The chassis is bereft of tube shields. The aforementioned tubes are shouldered glass. Are these shields necessary? Are matched 6F6G tubes necessary and will Russian tubes suffice?

Getting sound is wonderful. Getting fidelity is awesome. Making steady progress with your help: this couldn't be done without you. D**n the money; full speed ahead! Waiting for her to come home.

Made in America: nobody does it better!

Rick Ethridge
Plattsmouth, NE

[Arran]

 Yes, tube shields are necessary, at least with the 6Q7G, but thankfully if it is a 37-665 they used the tube shield bases that allow the use of a metal or a GT style tube in place of the G style tubes, a 38-665 would not. Yes, you can use Soviet/Russian tubes, as long as they are electrically the same as the North American type, but other then the power tubes most of their octal types were metal so there really is no price advantage in using Soviet/Russian octals.
 What makes you think that the output tubes were bad? If there is high distortion that's usually indicative of a biasing problem, not poor emissions. A power output tube could be gassy however, at that could cause distortion if they work at all. I would get a 6J5 if that's what the set calls for and the 6C5 is no good, the 6C5 is not an exact match to a 6J5 though it may still work in some circumstances.
Regards
Arran

[titan1a]

As I said, both 6F6G tubes are very weak. The 6K7G is barely good. The 6A8G tube is bad. A 6C5 was subbed for a 6J5G. The Russians tubes are cheap and matched.

Rick Ethridge
Plattsmouth, NE

[mikethedruid]

Well, if the 6A8G mixer/oscillator is bad, you are likely going to have some problems. Buy the needed tubes. It is always best to sort out those problems even before you start further diagnosis, once you have finished the basic rebuild and before alignment, so one thing doesn't mask or interfere with another problem. I'm following your work with interest. I have my eye on a 37-665 myself, but doubt I can get it while it is still in my price range. It looks fairly unmolested, and the cabinet is very nice. Good luck with your project.

[titan1a]

I hope you can get one. I paid $150 plus shipping on Ebay. I read this model was used for Apex radio frequencies. These immediately preceded FM. My repairman and I are both learning together. He just restored his RCA CTC-2B television and, before that, my Zenith 7S363. The radio will need help on the top from weathering and water damage. I seriously want this radio to come out OK. I believe Philco, for the most part, made much better radios than Zenith. I salivate whenever I think of my old/new receiver operating in the living room near the fireplace. Thank you for your reply!

Rick Ethridge
Plattsmouth, NE

[titan1a]

I'm still looking for the SPRING CLIPS that fasten the shadowmeter to the bezel. If I can't find one other methods, including gluing, maybe necessary. Someone help me find them or instruct me how to create them!

Rick Ethridge
Plattsmouth, NE

[mikethedruid]

Rick, before you go to a make shift method like glue, try placing an ad for the clips here http://www.philcoradio.com/phorum/forumd...php?fid=17  . Also, you might ask this question more directly about how the clips work, or making a substitute, here but ask more directly, put "Shadowmeter mounting question" as the title and subject line. You should get an answer from someone knowledgeable on this particular, which, sadly, I am not.

[titan1a]

My repairman has started working on the electrolytic and some of the wax caps. He's found the usual rusted bolts to contend with. He had an accident and partially creased the speaker (repairable) but can't unfasten the bezel/escutcheon. After this come the tubes.

Rick Ethridge

[sam]

RICK

TWO pages on this post about how to fix your radio
 and you did NOT even replace any caps  ???  

sam

[titan1a]

Tubes tested first. Most caps replaced second. I'm still missing some parts but I'm hopeful they can be procured. Next will be the tube replacement, installation of replacement parts then, hopefully, a tune-up. This is the first time I've had a radio like this repaired and it's not a small undertaking to me. I look forward to her being brought home and placing her in a place of honor.

[titan1a]

Great news! Repairman found and replaced bad caps resulting in greatly improved fidelity. Not all the caps are being replaced as many low power units have kept their tolerances. I've tried my best to scour the web to find elusive information successfully (so far).

I thank all of you who have been so kind helping. The vintage Philco community has bent over backward to help me restore my beloved tombstone to functionality. I owe you a great debt. When my "baby" returns home, when I listen to her, I will think of you all. Your pictures and advice have been crucial to her restoration. Your published books will be purchased with gratitude. Where I can help, I will try hard to be of service as I learn more. I'm still a novice at this.

Bless you all!

[mikethedruid]

A piece of advice, when you have it open and replace caps, it pays to replace ALL the paper/wax caps, and all the electrolytic caps, and any non mica small value caps. I always replace with caps of higher voltage rating than the original, and as close as I can get to original value capacitance using modern standard values. With the resistors you only really need to replace out of tolerance ones, but I usually just go ahead and replace them all unless they are too tough to get at and are OK tolerance wise. Again, I use modern 1 watt for the old 1/2 watt resistors, as they are about the same size, and provide extra margin, and also go up similarly with higher wattage resistors also. This way I minimize the chance that I will have to go back in at some time in the near future because some other aging part has failed. It has been fun reading about your restoration. Good luck with your "new" Philco. I look forward to seeing posts from you in the future.

[Eliot Ness]

Great news! Repairman found and replaced bad caps resulting in greatly improved fidelity

Mike just said it and many others have also, but it bears repeating.  You need to replace all of the wax/paper and electrolytic capacitors while the set is being repaired or they will fail at some point when you have the set all back together and listening to it.

Not all the caps are being replaced as many low power units have kept their tolerances.

 
Modern meters check the actual value of the capacitor but not at its rated voltage where it is most likely to fail or have excessive leakage.  Just for kicks I usually test all the paper caps that I replace and while some still read within tolerance, virtually all of them fail the leakage test at their rated voltages.  The only way to fully test those old capacitors is with an older cap tester that will apply true working voltage.

Rick, we don't replace those old caps because we enjoy doing it, but because we know if they aren't causing problems now they will in the near future.  We want you to enjoy listening to your tombstone radio without having to pull the chassis out again because of bad capacitors.

[titan1a]

Radio is now making the sound like that of frying bacon in the background regardless of volume level. Missed a cap or a bad tube? Otherwise it is the best sounding AM radio I ever heard.

Rick Ethridge

[titan1a]

My repairman came over and we exchanged information. The "frying bacon" sound is coming from a microphonic 6F6 output tube. All the electrolytic and almost all the wax caps are replaced. The var-cap is removed to replace the worn-out grommets. I found one spare 6F6 tube in my stash but need another. New tubes will be ordered next week then the chassis will be reassembled and the shadowmeter installed and adjusted and the unit realigned while waiting for the new dial. After this then we restore the cabinet! Three months left?