06-19-2018, 10:51 PM
Grid Leak Resistor
I liked the way the original grid leak resistor looks - and it has that nice holder under the chassis, so I just soldered on a small 1/2W 4M resistor to it. Voila! 2M gridleak resistor.
It did seem to be an improvement in reception over the original (drifted) 3.7M value.
Alignment And Neutralization
This was the first time I've neutralized a TRF set. The neutralization procedure is well-documented.
The first step was to build the described adapter from a junker chassis 4-pin socket and a dead 80 tube base:
[Image: https://farm1.staticflickr.com/892/42863...1b37_c.jpg]
[Image: https://farm2.staticflickr.com/1823/2804...7904_c.jpg]
Next I did the RF alignment as described and then went through the neutralization procedure for each RF stage.
[Image: https://farm1.staticflickr.com/892/42863...402b_c.jpg]
Reception and Hum
After alignment the set works quite well.
In fact I detuned the 3rd RF slightly because it was just too loud even at minimum volume on the stronger stations. There's a pretty long antenna for the workbench in the garage.
(I checked the volume control and it reads OK at 8K vs 10K expected - and has a good ground connection on one end.)
Mike - here's a video of what it sounds like tuning around the dial.
[Video: https://youtu.be/8VY1uutZIv0]
There is a low (60Hz?) hum that is more noticeable between stations but doesn't really affect listening.
Is that what you heard with yours?
P.S. Ты заметил наш российский канал?
I liked the way the original grid leak resistor looks - and it has that nice holder under the chassis, so I just soldered on a small 1/2W 4M resistor to it. Voila! 2M gridleak resistor.
It did seem to be an improvement in reception over the original (drifted) 3.7M value.
Alignment And Neutralization
This was the first time I've neutralized a TRF set. The neutralization procedure is well-documented.
The first step was to build the described adapter from a junker chassis 4-pin socket and a dead 80 tube base:
[Image: https://farm1.staticflickr.com/892/42863...1b37_c.jpg]
[Image: https://farm2.staticflickr.com/1823/2804...7904_c.jpg]
Next I did the RF alignment as described and then went through the neutralization procedure for each RF stage.
[Image: https://farm1.staticflickr.com/892/42863...402b_c.jpg]
Reception and Hum
After alignment the set works quite well.
In fact I detuned the 3rd RF slightly because it was just too loud even at minimum volume on the stronger stations. There's a pretty long antenna for the workbench in the garage.
(I checked the volume control and it reads OK at 8K vs 10K expected - and has a good ground connection on one end.)
Mike - here's a video of what it sounds like tuning around the dial.
[Video: https://youtu.be/8VY1uutZIv0]
There is a low (60Hz?) hum that is more noticeable between stations but doesn't really affect listening.
Is that what you heard with yours?
P.S. Ты заметил наш российский канал?
