[LDel]

Thank you for accepting me into the group. I hope I'm on the correct thread to ask my question. This is my first restoration of a Philco 60B (1933). I'm smart enough to know when to ask someone more knowledgeable than I, so here goes: I have taken two, Philco 60B chassis and combined them into one radio. Both radios were BADLY abused i.e. grill cloth and speaker cone ripped out, mica trimmer caps missing, antenna coil and 1st IF missing, chassis left outside in bad weather, etc. - You get the idea. I was able to harvest enough parts to make one complete set. I re-stuffed the condenser blocks, replaced out of tolerance resistors, re-wound the oscillator transformer primary, and replaced decrepit wiring. All IF's and the antenna transformer show continuity. The tuning condenser was so badly rusted and filled with debris, that it had to be soaked, overnight, in vinegar to clean it up. (Yes, I removed the mica trimmer caps first.) As of yet, I do not have a dial, or the 1/4 inch plastic alignment tool - both have been ordered. I can inject various modulated RF signals at the antenna post, and by rotating the tuning condenser, I can hear the tone in the speaker. However, I am not able to tune in stations - I just get LOUD static in places that seems to indicate the presence of a station. Does the fact that I can hear different modulated RF frequencies indicate that everything is in working order, and I just need to do an alignment? It will be another month before I receive the dial and alignment tool, and I don't want to waste time, if I should be looking for another problem. On a side note: It's been over 30 years since I've done work like this. I never was fantastic, but I could usually get a set to work. I'm hoping by reading/studying/and following this forum I can become more proficient. Thanks in advance for any/all responses.

[Ron Ramirez]

Welcome.

We split your initial post into its own thread in case you're wondering.

Also, the 60B was made from 1933 through 1936 - it is not a 1931 model.

Stand by for good responses from some good people...

[Radioroslyn]

Hi and welcome,

Connect your well calibrated signal generator to the ant post. Set the radio's tuning dial @ 550kc or so. Generator for 460kc 400cy modulated tone attenuation full up (max output). Adj # 17, 18, and 26 for max signal while adjusting the generator's output down so as not to overload the receiver. 
Use an ac voltmeter across the voice coil to measure the output. Or a hi impedance analog voltmeter to measure the avc voltage for finding the peak output.
This completes the IF alignment.

[LDel]

Thank you for your response - I am VERY appreciative.  Based on your response, the IF sections need to be aligned, as they are the culprit. I have aligned sets, in the past, so the procedure doesn't scare me.  I'll need to wait until I get a replacement phenolic dial, and a 1/4 inch plastic alignment tool.  I'll re-post with the results.  Many thanks.

[Radioroslyn]

To do the IF alignment you don't need the dial on the set just close the tuning cap. Tuning cap shouldn't have any effect on the IF.

[fenbach]

radioroslyn, i need you to set me straight. you say, "Connect your well calibrated signal generator to the ant post...and Adj # 17, 18, and 26 for max signal." not to the IF tube [78] first, then to the 6A7??

and, LDel, your radio may have a padder 26A if it's a later run. see

https://web.archive.org/web/201603160007...60evol.htm or

https://philcoradio.com/library/index.ph...-model-60/

you'll find some alignment instructions on pg 76 of

http://www.silverslingshot.com/PDFFILES/...s_1937.pdf

[LDel]

Thanks again - there's SO much for me to learn.  That's why I'm here.

[LDel]

Fenbach - Thanks for the links.  My radio is an early run.

[Radioroslyn]

It's the trimmers that are in parallel with the primary or 2ndry of the windings in the IF transformers. I just took a quick look at this: http://www.nostalgiaair.org/pagesbymodel...013793.pdf Note the 2ndry of the 2nd transformer has no trimmer it's untuned. Go over them a couple of times to be sure all are at the peak. Sometimes there is some interaction between them.

If you connect the generator directly to the tube's element that is connect the transformer it tends to load the circuit and not give an accurate alignment.

[LDel]

...will do.

[LDel]

Radioroslyn - I grew tired of waiting for the plastic alignment tool to arrive, so I made a few calls and managed to borrow one.  (Unfortunately, the person from whom I borrowed it, inherited it from his father, and he doesn't know a thing about radio repair - so he can't help me.)  I'm not able to inject a 460KC at the antenna clip.  The lowest frequency that will pass is 560KC - and that is EXTREMELY faint, and adjusting the caps makes no difference.  (I do not have a frequency counter, but the generator has always been accurate for past alignments.)  However, there appear to be other problems that an alignment is not going to fix:  

I decided to take some voltage measurements.
 
The 42 output is okay.
  
The 75 P-K is 278 (should be 250) the CG-K is .55(should be .15)

Moving backward, the 78 readings are worse:  P-K reads 278 (should be 250). SG-K reads 271 (should be 120) CG-K reads 3.49 (should be.18) 

Worst of all is the 6A7.  The P-K is 255 (should be 250). That's the only reading I can take, as the digital multimeter jumps all over the place and flashes AC.  I realize that incoming signals are AC, (at least that is what I learned) but the Model 60 directions specify DC voltage measurements, with the exception of filament voltages.  I must confess that I am only vaguely familiar with a pentagram converter - it appears to be 2 tubes in one.  This tube tests okay on my tube tester. 

The schematic does not appear all that complicated, but obviously, at this moment, I'm over my head.  Any clarification would be greatly appreciated, as would some direction, as to where to begin investigating.  Many thanks, in advance.

[Radioroslyn]

It would seem that your 78 is a bit weak as it's not drawing enough current to cause a voltage drop across it's screen resistor. This will effect the amount of plate current it draws. That could be the reason for the high reading on the 78.

As for the generator if you have a local station at 920kc you can use it's carrier beat against the signal from the generator as it's the 2nd harmonic of 460kc.

[mikethedruid]

I've been reading your thread, Del, and here are some thoughts. First, I trust you have replaced all the paper condensers and the electrolytic condensers. That should be done before anything else. Now, with the problems you are describing, check all the resistors with the radio OFF and UNPLUGGED. Any that are beyond their specified tolerance (usually 20%, but sometimes less, as will be noted on the schematic, and with a gold (5%) or silver (10%) marking on the resistor) should be replaced. Last, I have a trick I use for injecting the IF frequency into a radio. I took a toilet paper tube, and have wound a coil of 22 gauge PVC insulated wire around it, about 30 turns. I put a .01mfd condenser in series with it, and feed this directly from my signal generator, the other lead of the .01 mfd condenser to the signal lead from the sig gen, and the other end of the coil connected to the ground lead from the sig gen. I slip this over the mixer oscillator tube, and it induces the proper IF frequency into the tube. This doesn't work with metal RCA tubes, but you shouldn't use them in a Philco anyway. One can also detach the grid cap wire from the mixer oscillator tube, and inject the signal directly there, using a .01 mfd condenser in series with the signal lead from the sig gen. Lastly, for adjusting the little variable caps in the IF cans, I made a little brass screw driver from some 1/16" dia. brass rod you can buy online or at Home Despot by grinding a straight blade on one end, and bending the other into a handle, then insulating the handle with a layer of black electrical tape. Works great, and is non=magnetic, so it doesn't influence the IF response of the coils being adjusted. I hope these tips are of help to you. Good luck !

[LDel]

Mikethedruid - Thank you for your input.  The electrolytics were replaced - cutting the tubes apart and re-stuffing them was the first thing that I did.  All condenser blocks were re-stuffed and out of tolerance resistors were replaced.  As with you, I always place a .01 cap in series with the signal generator leads.  Yes, I also tried feeding the signal directly in the cap of the 6A7 tube - no luck.  I do like the idea of the PVC coil that you made - I'll have to try that sometime.  As for the alignment tool - you're very creative!  I am beginning to find that creativity is part of radio repair.  That and LOTS of tenacity!

[LDel]

Radioroslyn - I rechecked the 78 on the tester, it tests okay - but I know that's not the same as working in a real circuit.  I'll check my tube boxes to see if I have another 78 tube.  If that doesn't change things, I'll trace the circuits to the tube.  You've given me a direction to follow - I appreciate it.  I'll let you know how it works out.

Unfortunately, there are no radio stations, in this area that broadcast at 920KC.  I found it interesting that you mentioned this - I forget the details, as to why, but I had to double the frequency to get the results I wanted.  I'm a retired, classically trained musician.  We call that first harmonic - one octave higher.

Many thanks for your guidance.