[Jay Thomas]

I have been restoring a Philco Model 80 and have two questions: 1)  What can be used for the dielectric material for the sensitivity control?  The material in my radio sensitivity control has pretty much disintegrated.  I was thinking about some thin plastic material, but thought I would find out if anyone has replaced the dielectric material and with what. 
2)  I have completely recapped the radio, replaced all weak resistors, etc.  Tubes check good.  When tuning in stations, when I keep my fingers on the volume control, the signal (volume) is loud until I release my fingers from the knob.  I have a 12' antenna.  I tried grounding the chassis, but that did not make a difference.  I also installed the "gimmick wire" but that did not make any difference with or without it.  I have plenty of volume otherwise.

Thanks for any help!

[Radioroslyn]

Hi Jay,
Well lets do a bit of troubleshooting. Unplug your Jr and turn the volume control full up. Measure the resistance from the ANT to the GND posts on the chassis. Should read about 3 ohms if not primary of the antenna coil is bad. Not difficult to repair.

Terry

[Jay Thomas]

Hi Jay,
Well lets do a bit of troubleshooting. Unplug your Jr and turn the volume control full up. Measure the resistance from the ANT to the GND posts on the chassis. Should read about 3 ohms if not primary of the antenna coil is bad. Not difficult to repair.

Terry

Thanks Terry.  My Jr does not have the posts.  However, I checked the resistance between the ground wire and the ANT and I get 7 ohms with volume full up.  I turned the volume control all the way down, and I get zero ohms.  As I turn the volume control up, I do not get any reading until about 3/4 the way to full up.  A large space where no resistance is detected.

Jay

[Radioroslyn]

Seems like your coil is ok but pot is bad. If you connect your antenna to the wiper of the pot do you receive signals ok? If so your pot is open. Suitable replacement would be one from 10K-50K.

Terry

[Jay Thomas]

Seems like your coil is ok but pot is bad. If you connect your antenna to the wiper of the pot do you receive signals ok? If so your pot is open. Suitable replacement would be one from 10K-50K.

Terry

Thanks again.  I will give it a try.  I am able to control the volume okay.  My body is acting like an antenna when I hold on to the volume control knob.  Like I mentioned before, the volume increases when I am holding the volume control knob, and decreases when I let go.  But I can raise and lower the volume okay otherwise. 

Any thoughts or ideas about what I can use for insulation material to replace the dielectric material in the sensitivity control?  It probably is the same material used in all of the old tuners for adjustments.  Looks like an early thin plastic material.

Here is another question maybe you can help with...I use a transmitter to listen to music on all of my AM radios.  The music comes in very clear.  I have 3 Philco cathedrals, a model 20, 80 JR and 81 JR.  Sound is distorted on all 3 from the transmitter, but clear on normal radio transmissions.  Is this normal on these older radios?  I have an AMT3000.  Maybe too powerful for the older radios? 

Thanks for any comments.

Jay

[Radioroslyn]

Seems like your coil is ok but pot is bad. If you connect your antenna to the wiper of the pot do you receive signals ok? If so your pot is open. Suitable replacement would be one from 10K-50K.

Terry

Thanks again.  I will give it a try.  I am able to control the volume okay.  My body is acting like an antenna when I hold on to the volume control knob.  Like I mentioned before, the volume increases when I am holding the volume control knob, and decreases when I let go.  But I can raise and lower the volume okay otherwise. 

Any thoughts or ideas about what I can use for insulation material to replace the dielectric material in the sensitivity control?  It probably is the same material used in all of the old tuners for adjustments.  Looks like an early thin plastic material.

Here is another question maybe you can help with...I use a transmitter to listen to music on all of my AM radios.  The music comes in very clear.  I have 3 Philco cathedrals, a model 20, 80 JR and 81 JR.  Sound is distorted on all 3 from the transmitter, but clear on normal radio transmissions.  Is this normal on these older radios?  I have an AMT3000.  Maybe too powerful for the older radios? 

Thanks for any comments.

Jay

Sent pm.

Terry

[Jay Thomas]

There is enough dielectric material left in the control so this is a non-issue.  As far as the transmitter and the distortion, the farther away I can get the radio from the transmitter, the clearer the signal.  No further help on these issues is necessary.

Thanks,

Jay

[Raleigh]

I have an SSTRAN, which I use to transmit to my old radios. A few of them, all with RF amplifier stages, distort when listening to the SSTRAN but not when listening to a "real" station.

I partially solved this by dialing back the modulation control on the transmitter. All of them sound less distorted now. I don't know if you have a modulation or gain control on your transmitter. If not, maybe you can play around with your transmitter antenna length and placement.

It could also be that your transmitter is distorting the signal. How does a modern radio known to be good sound receiving your transmitter?

[Jay Thomas]

I have an SSTRAN, which I use to transmit to my old radios.  A few of them, all with RF amplifier stages, distort when listening to the SSTRAN but not when listening to a "real" station.

I partially solved this by dialing back the modulation control on the transmitter.  All of them sound less distorted now.  I don't know if you have a modulation or gain control on your transmitter.  If not, maybe you can play around with your transmitter antenna length and placement.

It could also be that your transmitter is distorting the signal.  How does a modern radio known to be good sound receiving your transmitter?

My transmitter is an SSTRAN also.  I dialed back the modulation control, but the signal seemed better to raise it a little.  I am sure the transmitter is causing the distortion to the three cathedrals.  I have about 45 other radios that I have restored (1939-1952).  These all sound great with no distortion.  Just seems that the problem is with my 3 early cathedrals.  I have two of cathedrals in the same room as the transmitter where all of my radios are on display.  I may try to relocate the antenna like you suggest, or one of the radios into another room.
Thanks for your suggestions.

Jay

[Jay Thomas]

Seems like your coil is ok but pot is bad. If you connect your antenna to the wiper of the pot do you receive signals ok? If so your pot is open. Suitable replacement would be one from 10K-50K.

Terry

Thanks again.  I will give it a try.  I am able to control the volume okay.  My body is acting like an antenna when I hold on to the volume control knob.  Like I mentioned before, the volume increases when I am holding the volume control knob, and decreases when I let go.  But I can raise and lower the volume okay otherwise. 

Any thoughts or ideas about what I can use for insulation material to replace the dielectric material in the sensitivity control?  It probably is the same material used in all of the old tuners for adjustments.  Looks like an early thin plastic material.

Here is another question maybe you can help with...I use a transmitter to listen to music on all of my AM radios.  The music comes in very clear.  I have 3 Philco cathedrals, a model 20, 80 JR and 81 JR.  Sound is distorted on all 3 from the transmitter, but clear on normal radio transmissions.  Is this normal on these older radios?  I have an AMT3000.  Maybe too powerful for the older radios? 

Thanks for any comments.

Jay

Sent pm.

Terry

Hi Terry:  You were right!  The pot was bad.  It tested good with an ohm meter.  I happened to have another Philco pot and replaced it and no longer have the problem where I act as an antenna. Never would have suspected this.

Thanks for your help.

[Radioroslyn]

>Hi Terry:  You were right!  The pot was bad.
You thought other wise?????
Just kidding my friend.

I've seen a number of them go open from a lot of use. They also seem to be a little hard to find a replacement. Nobody has a 20K pot w/sw

Glad to point you in the right direction.
Terry