Model 80 Mods - Printable Version
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Model 80 Mods - Mike L - 10-03-2016
Making progress on my model 80. It is playing well and the voltages seem more in line now that I can check them with a VTVM. At a later date I think I will need an alignment to peak performance. I receive stations all along the dial range. However there is one station on the 150 dial location that is very strong, but very distorted.
Following Ron's mods: I have changed resistor #9 to a 13k 3 watt. Changed resistor #16 to a 2meg. Now I'm getting ready to change the connection of resistor #5 and cap#6 with respect to their connection to the antenna coil. Which brings up the question of the "gimmick". In the performance modifications on his website there is one wire with three turns wrapped around the volume control wiper lead and then connected to the cathode of the detector-oscillator tube. Simple enough, but then I found an earlier post on the subject where there were two wires. One connected to the cathode of the detector-oscillator tube the other wire connected to the volume control center tap with the free ends overlapping about an inch and twisted together. Which is correct? Then It dawned on me I have a model 84 sitting here as a next project. Different still. That gimmick wire is indeed wrapped around the volume control wiper lead, but then is connected to the oscillator-transformer. Photo below is my model 84 with the solder tool pointing to the connection.
While the radio is playing there is a definite boost in volume if I touch my finger to the shaft of the volume control. Is this what the gimmick is intended to do?
RE: Model 80 Mods - Radioroslyn - 10-03-2016
What it does is add some osc signal (from the 36's cathode) to the input of the mixer. This improves the ability to the mixer to handle stronger signals without overload and generally improves the mixing action.
By touching the volume control you are asenually are bypassing it and adding more rf signal, that's why it gets louder.
RE: Model 80 Mods - Mike L - 10-08-2016
I completed all of the mods recommended. It plays and receives stations all across the dial, but reception is really not improved. If anything it is worse as I need a longer antenna wire with the radio upstairs out of the basement. There is also a hum like a florescent light interference which wasn't there before. Maybe it just the time of day, but 700 WLW is just a stones throw away and I thought reception would be better. Maybe I did something wrong?
