I am working on a Philco 40-150 code 121 at the museum. The electrolytic and paper capacitors have been replaced. All tubes have been checked.
The problem is that I receive 1500 KHz at 530 on the dial, 580 on the dial, and 1500 on the dial.
What is going on? All suggestions are appreciated.
Thanks,
nv3g
Oscar -
I recently finished restoration on my 40-150. Beyond replacing the paper and electrolytic capacitors, may I also suggest that you replace the mica capacitors also. I replaced all of the ones in my set-some were made by Micamold, mica capacitors that have gotten a reputation lately to be as defective and leaky as the old paper capacitors. One word of caution if you choose to do that-the values for the micas in the service data are the values you want to use. The color codes on the caps in my set did not follow the usual accepted mica capacitor color code. So, replace a 5 mmf capacitor in the chassis, and in the service literature with a new 5 mmf capacitor, even if the color code on the actual cap itself is different than what the color code for a 5 mmf cap. should be.Don't confuse yourself. Also, I replaced all the resistors. A lot of people will tell you it's not necessary to replace all of the resistors, only the out of tolerance ones, but I do a complete overhaul on my radios. I did notice when I was setting the push buttons on my set that 1600 came in when adjusting the trimmers for the lower frequency button settings. With regular dial tuning, however, stations didn't come in at several points as you describe after I did the electronic overhaul, and did an alignment as best as I could.
Hi Oscar,
Sounds like image rejection problems to me. Are you using the original antenna/loading gizmo shown in the schematic as p/n #1? Without that the circuit may not resonate and cause the problem you describe.
If you do have it and suffer from images a good alignment may cure it.
Good luck,
Bill
Thanks, Bill. I am ending up with egg on my face. I used a long wire antenna instead of the regular antenna which connects to the four terminals on the back of the set.
Thank you all for getting me back on the track.
nv3g
Oscar