01-01-2014, 05:51 PM
Well, there is good news and bad news tonight...
First, the good news: The 91 lives! I decided that just in case I had made an error rewinding the oscillator coil, I would try another coil - if I had one.
As it happens, I have a small stash of coils. In the box was an oscillator coil! I do not know if it came from a 71, 89 or 19, but it is the same type of coil, with the same pinouts.
The cathode winding needed to be rewound, so I did that.
Installed it and the set began to work!
I've let it play for over an hour and the power transformer is only lukewarm. Considering it had been overheated in the past, to the point of leaking out a lot of wax, I find that pretty amazing.
Now, the bad news:
The tracking is way off. I can not tune in 1400 kc. Tuning the signal generator around, I managed to get 1190 kc at 140 on the dial. My SSTRAN, which is set at 660 kc, comes in at 75. So the entire AM band is shifted upward on the dial from where it should be. Adjusting the high frequency oscillator trimmer only managed to move things back down the dial somewhat before the adjustment screw started coming loose.
No, I have not tried the low frequency padder, simply because that adjustment is supposed to make the tuning condenser track properly with the IF.
Oh, and the tuning condenser seems to be very dirty and the tuning cuts out - loudly - at various spots on the dial. There is no obvious visible rubbing of the plates.
The tuning condenser, incidentally, is the same type as used in the 1933-34 models 14, 17 and 18 rather than the large type used in the earlier 91 and the 71. So this must be one of the last production 91 receivers.
So...am I looking at adding or removing turns on the oscillator coil secondary (the winding which the tuning condenser is connected to)?
First, the good news: The 91 lives! I decided that just in case I had made an error rewinding the oscillator coil, I would try another coil - if I had one.
As it happens, I have a small stash of coils. In the box was an oscillator coil! I do not know if it came from a 71, 89 or 19, but it is the same type of coil, with the same pinouts.
The cathode winding needed to be rewound, so I did that.
Installed it and the set began to work!
I've let it play for over an hour and the power transformer is only lukewarm. Considering it had been overheated in the past, to the point of leaking out a lot of wax, I find that pretty amazing.
Now, the bad news:
The tracking is way off. I can not tune in 1400 kc. Tuning the signal generator around, I managed to get 1190 kc at 140 on the dial. My SSTRAN, which is set at 660 kc, comes in at 75. So the entire AM band is shifted upward on the dial from where it should be. Adjusting the high frequency oscillator trimmer only managed to move things back down the dial somewhat before the adjustment screw started coming loose.
No, I have not tried the low frequency padder, simply because that adjustment is supposed to make the tuning condenser track properly with the IF.
Oh, and the tuning condenser seems to be very dirty and the tuning cuts out - loudly - at various spots on the dial. There is no obvious visible rubbing of the plates.
The tuning condenser, incidentally, is the same type as used in the 1933-34 models 14, 17 and 18 rather than the large type used in the earlier 91 and the 71. So this must be one of the last production 91 receivers.
So...am I looking at adding or removing turns on the oscillator coil secondary (the winding which the tuning condenser is connected to)?
--
Ron Ramirez
Ferdinand IN
