The PHILCO Phorum

I'm in the process of redoing a 41-290. I've got the electrical portion pretty well finished. The AM band picks up a few local stations quite well. The other two bands pick up several transmissions, but they are rather garbled. I suppose that the transmissions are SSB. I have the schematics and other service info that I had ordered from Chuck which includes the alignment instructions. I don't have any access to any equipment like a signal generator and I don't really want to go out a buy one as this is pretty much a one-off project. Is there a simple procedure to check the alignment without having to resort to any test equipment, or should I just leave well enough alone since the AM band seems to be working quite well?

I haven't had the radio powered up for too long yet to really check it's performance. Also, my work area is right next to the main power panel which does seem to have a big effect on the little AM/FM radio I have out there to listen to when I'm working. Should I move the radio to a more "RF friendly" area to get a better idea of it's performance?

During the electrical restoration, I had several question come up which were answered by the kind folks at this site that were a real big help.

Thanks!!

The simple is NO. You may be able to do a simple RF alignment be using stations of a known frequency but the IF you'll need to use a generator. Actually there not very expensive.
Terry

Other options are:
1) If you have a friend that is a ham radio operator or collects old radios, you could ask him/her.
2) Are there any antique radio clubs in your area? If so, you might inquire of them whether a someone in the club would be willing to do the alignment.

Jon

Len, listen to them. I know some have said they can do it by ear on a radio station, my ears are not that good. The problem with listening to a radio station and trying to peak the IF is that their signal (sound) is not continuous. Same with peaking on a low and high frequency for RF. It goes up and down with the programming. Take a look at it with an analog meter on your speaker and you will see it fluctuate. Not good for finding a peak. What a sig gen will do for you is provide a consistent tone at the IF frequency or the RF frequency, that will make it easy to peak the sound (tone) coming out of the radio and your meter will provide you an accurate way to peak them. You can try the same with a DVM but the rapid change in the digits will drive your brain crazy. Both will work, one easier than the other.
Regards, Jerry

In a pinch, you can do a fairly decent alignment by connecting a VTVM or DVM across the AVC line and peaking the RF and IF stages for maximum negative voltage while tuning a local station. Since you are measuring carrier level, not audio modulation, a broadcast station can serve as a signal source.

It is certainly not as accurate an alignment done with a proper generator, but it will get you into the ballpark if the adjustments have not been tampered with and the IF is fairly close to its spec center frequency.

+1 for Mondial's idea. A much better way to do it than by ear. It should get you close. At least you don't have the dang modulation of a radio station jumping things around.
Jerry

Thanks for the suggestions. I may have found someone in the area who has the test gear and expertise to help.