05-26-2018, 10:02 AM
April 15-16.
I decided to rebuild and use the 38-116 RF unit instead of the 38-690 RF unit.
Why?
The 38-116 RF unit had unmolested tube shield bases.
I began the long, drawn-out process of removing one section of the RF unit at a time, replacing capacitors and resistors as I went. The main sub-base of the RF unit (where the tube sockets are attached) were also rewired...which took quite a bit of time.
Remembering my experience with my 37-670, I decided to replace everything...including mica caps.
[Image: http://www.philcoradio.com/images/phorum...90_055.jpg]
I replaced the original micas with new silver micas, or with NP0 (C0G) ceramics.
[Image: http://www.philcoradio.com/images/phorum...90_056.jpg]
In the case above, capacitor (19) was 130 pF. So I connected a 120 pF and a 10 pF in parallel to obtain 130 pF.
When this section (the middle section) was finished, here's how it looked:
[Image: http://www.philcoradio.com/images/phorum...90_057.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_058.jpg]
Now have a look at the oscillator section of the RF unit before I did anything to it.
[Image: http://www.philcoradio.com/images/phorum...90_059.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_060.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_061.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_062.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_063.jpg]
Coil (37) was bad. Notice the greenies in the middle:
[Image: http://www.philcoradio.com/images/phorum...90_064.jpg]
I checked the same coil in the 38-690 RF unit and, fortunately, it had good continuity! So I carefully removed it from the 690 RF unit and installed it in the 116 RF unit.
[Image: http://www.philcoradio.com/images/phorum...90_066.jpg]
While I was working on the RF units the evening of April 16 (my birthday), Debbie provided a very pleasant interruption:
[Image: http://www.philcoradio.com/images/phorum...90_065.jpg]
H B 2 Me!
I decided to rebuild and use the 38-116 RF unit instead of the 38-690 RF unit.
Why?
The 38-116 RF unit had unmolested tube shield bases.
I began the long, drawn-out process of removing one section of the RF unit at a time, replacing capacitors and resistors as I went. The main sub-base of the RF unit (where the tube sockets are attached) were also rewired...which took quite a bit of time.
Remembering my experience with my 37-670, I decided to replace everything...including mica caps.
[Image: http://www.philcoradio.com/images/phorum...90_055.jpg]
I replaced the original micas with new silver micas, or with NP0 (C0G) ceramics.
[Image: http://www.philcoradio.com/images/phorum...90_056.jpg]
In the case above, capacitor (19) was 130 pF. So I connected a 120 pF and a 10 pF in parallel to obtain 130 pF.
When this section (the middle section) was finished, here's how it looked:
[Image: http://www.philcoradio.com/images/phorum...90_057.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_058.jpg]
Now have a look at the oscillator section of the RF unit before I did anything to it.
[Image: http://www.philcoradio.com/images/phorum...90_059.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_060.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_061.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_062.jpg]
[Image: http://www.philcoradio.com/images/phorum...90_063.jpg]
Coil (37) was bad. Notice the greenies in the middle:
[Image: http://www.philcoradio.com/images/phorum...90_064.jpg]
I checked the same coil in the 38-690 RF unit and, fortunately, it had good continuity! So I carefully removed it from the 690 RF unit and installed it in the 116 RF unit.
[Image: http://www.philcoradio.com/images/phorum...90_066.jpg]
While I was working on the RF units the evening of April 16 (my birthday), Debbie provided a very pleasant interruption:
[Image: http://www.philcoradio.com/images/phorum...90_065.jpg]
H B 2 Me!
--
Ron Ramirez
Ferdinand IN