The PHILCO Phorum

I just finished one of these. It is the last in the 60 series, run 7 I believe. My question is this:

It plays strong and very clear and tracks well, but when tuning strong stations they overlap by about 35kc on either side of the station, i.e. when tuning 770, I hear the station from about 750 to 820 (820 is a weaker station and I hear both then). With 710 I hear it from about 690 to 750kc.

On strong lower frequencies (570 and 620) I get a squeal as I tune to them and i hear a slight oscillation. I switched the 6A7 and 78 tubes, but don't have a 75 to try in case it is a tube. I did change all caps and resistors except one mica. I did peak the IF's. What might cause this?

In comparison, I have a Zenith 5S29 that tracks well and strong, but it has less bandwidth when tuning. Is this just due to the different designs of these two radios or is something wrong with my 60?

Steve

Sounds like an oscillator/IF issue.

Did you replace the mica caps vic the 6A7 circuitry with values that were right on or very close?

Are you certain that you peaked on the highest response and not on a harmonic?

Did you follow the original placement of components/leads you replaced?
This does not always cause a problem but it can....

The mica that goes across the oscillator coil was changed and I didn't have a 110 pf cap. I did use a 96 pf instead. Would this do it?

It plays strongest on the desired setting in every case, it just "bleeds over" on either side of the station setting more than i think it should.

I would think that 96pF would be OK.

What are you using for an antenna?

I am using a wire wrapped around my window trim. It is about 12 feet long.

I am not too experienced in these things, but I would think that some combination of components would allow a different Q and result in a wider or tighter setting on either side of a chosen station (ie. less KC on either side). I just don't know where it may be on this set and if it is something I can adjust. I have read about this, but don't really understand it enough.

I also don't know if this is normal operation for this model.

You can do this by increasing or decreasing the IF and adjusting the corresponding padders, but it is hit or miss.

When you aligned, did you use a freq counter to verify the f from you sig gen?

Schematic and information here:
http://www.nostalgiaair.org/PagesByModel...013793.pdf

Agree, repeat the alignment. You can get an inexpensive digital frequency counter (probably less than $25 delivered) as just mentioned. If you have an older signal generator leave it on for at least half an hour before verifying and using it on the set. They all drift a bit before becoming stable. Anyway follow manufacturer's instructions for alignment.
Could be a carbon resistor going way up in value, no foolproof way to measure them, so for the few pennies each, I now replace them whilst doing recap job. I'd like my restorations to outlive me.

Well, do that, and then let us know what you have found.

I used a signal generator this morning and peaked the IF's at 460kc. My generator is accurate and i have a frequency counter to check. The Riders instructions are not clear. It just mentions the IF compensator locations and the high and low frequency compensators. No other instructions, so I put the signal through the antenna and ground connection as I have read and have done for most other alignments that have detailed instructions.

After peaking, there was still a good bit of oscillation as I tuned across the dial. The stations come in strong, but it still has what I would call a wide bandwidth, hearing the desired frequency about 30kc before and after the desired frequency. The signal/sound is very good when you get right to the station frequency, it is just that you can still hear it on either side more than I am used to on other radios I have aligned.

I then decided to detune the IF's just a bit and it helped a lot (acted like a regen set). The oscillation lowered quite a bit. Now I am only getting an oscillation at the lowest frequencies, 570 and 660. If I tune carefully, there is no oscillation on the station, it is only if I am slightly on either side of the station frequency.

All other stations above the low frequency ones work well and it is a big more selective as well now. I did change all resistors already and caps. I used it a few hours today and it played well except for the above.

Maybe this is normal for this set? Maybe i am too picky?

Without looking at the alignment instructions, I think there may be a portion where you input your signal at the grid of the 6A7.

The alignment instructions in Riders dont say where to inject the signal. I did try the grid of the 6A7 also but may not have done something right as I didnt see any change.

Here are comprehensive alignment instructions for late model 60 sets (with four IF adjustments and wave trap):

1. Remove the grid clip from the 6A7 tube. Attach a grid clip from a junk set to the 6A7 grid cap and clip the high end of your signal generator to this grid clip. Attach the low end (grounded end) of your signal generator to the Philco 60's chassis.

2. Do not rely on your ear. Connect an analog AC voltmeter, preferably, at the speaker between the green and white leads (plate and screen grid). Safety first! Do not do this with power on, else you will receive a nasty shock! Connect everything before applying power to the radio. You can use an analog multimeter, but not a digital one. It must be set to AC volts. If it has several volt range settings, start at a higher range and work your way down to a lower range until you get a strong reading on the meter without pegging the needle.

3. Turn the radio on, volume control all the way up, dial set at low end of AM band, tuning condenser plates fully meshed. Make sure the band switch is set to AM (counterclockwise). Adjust the signal generator to produce a 460 kc signal. Feed a modulated 460 kc signal into the 6A7 grid cap. Keep the signal as low as possible, just enough to barely hear the "beep" of the signal generator while being able to see good deflection on your meter. This is important!

4. Adjust the various screws, hex nuts, etc. as follows, using the illustrations below to guide you to the locations of the various adjustments. Use a plastic or Bakelite 1/4" hex adjusting tool designed for adjusting Philco trimmers; a metal socket wrench will throw the adjustments off to a certain degree.

5. Adjust trimmer (26A) for maximum output.

6. Adjust trimmer (26) for maximum output.

7. Adjust trimmer (18 ) for maximum output.

8. Adjust trimmer (17) for maximum output.

9. You should notice as you adjust these, that the signal will get louder. Reduce the output at the signal generator as this happens. You want to keep the input signal weak, barely audible.

10. Remove the temporary grid clip from the 6A7 grid cap and reattach the proper grid clip to the 6A7 tube. Unhook your signal generator.

11. Now, connect one lead of a 200 pF mica or ceramic condenser to the antenna clip of the set. Connect the high end of your signal generator to the other end of this condenser. Low end of the signal generator to chassis ground as before.

12. Crank up the output of the signal generator, which is still set at 460 kc. For this next adjustment, you want a loud signal.

13. Adjust the wave trap trimmer (accessible through a hole in top of the chassis) for minimum output.

14. Now set the signal generator for a 1400 kc signal and turn it down again; for the remaining adjustments, we want the weakest possible signal from the generator once again. Tune the radio to exactly 140 on the dial.

15. Adjust trimmer (6) for maximum output.

16. Adjust trimmer (5) for maximum output.

17. Tune the signal generator to produce a 600 kc signal. You may have to turn up the generator output for a louder signal here. After doing this, find the signal on the dial of the set; it will be near but probably not exactly at 600 kc.

18. Now we will adjust trimmer (12). This is adjusted differently than all of the others. Here, we will utilize a process known as rocking. What you need to do now is, find the signal on the dial. Now, adjust the trimmer (12) either clockwise or counterclockwise very slightly. Turn the dial of the radio to find the signal again. Note in the meter whether the signal is higher or lower than before. If lower, turn trimmer (12) in the opposite direction and try again. If the signal is louder, continue turning (12) slightly and finding the signal with the tuning knob, watching the meter to see if the signal continues to increase in strength. Eventually, you will come to a point where the signal does not get stronger and in fact will start to get weaker. When this happens, adjust (12) slightly in the opposite direction from how you were turning it to find the peak again. At this point, the 600 kc signal may not appear exactly at 60 on the dial. That does not matter. What you have done is to align the set's oscillator to track properly with the set's IF chain. This step is important for best operation of your radio.

19. Now, you must set your signal generator back to 1400 kc and, still using the lowest possible signal so that it is barely audible yet reads well on your meter, repeat steps 14 through 16.

20. Congratulations, your 60 is now properly aligned.

Thanks Ron,

I will try this and let you know how it turns out.

Steve

I aligned the set according to the instructions and the set is yet more selective. I think it is as good as it will get. It does track well also. I am pretty happy at this point.

Thanks Ron, Terry and Codefox for your help,

Ron,
can i assume the procedure will work for the early model 60 as well as the late ?