07-16-2008, 05:46 AM
I have a Philco CT-2 that was restored and ready to install in a 1934 Plymouth PJ and is now acting strangely.
When 6 VDC on a positive gorund is applied, the tubes light up nicely (except for possibly the #77 tube, I can't get a good vantage point to see if it lights) and the vibrator begins to hum. At first, when using a signal generator, I wasn't able to pull a signal in. I then gave the side of the radio a few good thumps and it seemed to jar the vibrator into a better working state. I was then able to pick up freq's from the sig. gen.
Before thumping the side, the radio was drawing about 3.5A and post-thumping, the raio was drawing 4.6A. Possibly a bad vibrator?
The problem other than the above:
#1 - I can only get a good signal down to 800 KHz. I have no problem pulling a good tone in the uppers but it cuts out when I get down to 800 and below.
#2 - When I was taking voltage readings from the underside of the chassis (the tubes), I thought that I might have heard a little arcing, could this also be the Vibrator?
#3 - If I rock the radio while at a "good" freq. above 800, the radio tends to cut in and out.
#4 - If I touch a screwdriver to the grid cap, tube shield or case, it seems to change the amplitude of the signal. Could this be a ground problem?
#5 - The #77 tube doesn't appear to be lighting, but I can't be 100% sure. When I measured between pins 1 and 6 I got continuity (heater)
I'm fairly new at playing with antique car radios and still have a lot to learn. These seemingly multiple problems are really confusing. Part of me says that I should replace the Vibrator / take it apart and clean up the contacts.
Any help on this topic would be greatly appreciated. Thanks!
When 6 VDC on a positive gorund is applied, the tubes light up nicely (except for possibly the #77 tube, I can't get a good vantage point to see if it lights) and the vibrator begins to hum. At first, when using a signal generator, I wasn't able to pull a signal in. I then gave the side of the radio a few good thumps and it seemed to jar the vibrator into a better working state. I was then able to pick up freq's from the sig. gen.
Before thumping the side, the radio was drawing about 3.5A and post-thumping, the raio was drawing 4.6A. Possibly a bad vibrator?
The problem other than the above:
#1 - I can only get a good signal down to 800 KHz. I have no problem pulling a good tone in the uppers but it cuts out when I get down to 800 and below.
#2 - When I was taking voltage readings from the underside of the chassis (the tubes), I thought that I might have heard a little arcing, could this also be the Vibrator?
#3 - If I rock the radio while at a "good" freq. above 800, the radio tends to cut in and out.
#4 - If I touch a screwdriver to the grid cap, tube shield or case, it seems to change the amplitude of the signal. Could this be a ground problem?
#5 - The #77 tube doesn't appear to be lighting, but I can't be 100% sure. When I measured between pins 1 and 6 I got continuity (heater)
I'm fairly new at playing with antique car radios and still have a lot to learn. These seemingly multiple problems are really confusing. Part of me says that I should replace the Vibrator / take it apart and clean up the contacts.
Any help on this topic would be greatly appreciated. Thanks!
