06-02-2014, 11:20 AM
Happy Monday!
I picked up a 39-7 a couple of months ago. decided to start work on the chassis yesterday.
bad news.. it was a mouse-buffet at some point. ate the paper off one of the paper caps! good news is that I managed to get the antenna coil back together (no broken wires, lucky me) bad news is, the bugger ate a hunk out of the primary on the 2nd I.F. (#11 on the schematic)
since this set's IF is 470, I'm wondering if I there's enough adjustment in the padder to use a 455 coil?
I do have a 470 2nd IF donor, but.... it's 2 5/8" long and would span more than half the chassis underneath and cause me to re route wiring and possibly have the center terminal strip in the way. also, it ohms out kinda low on the secondary 1.2 ohms. the primary is @ 19.8.
not sure if this is truly an option or not, but I'm considering the source, Norm Leal. he wrote:
"With IF Transformers use small capacitors
between the plate of the driving tube to the grid of the
driven tube. This will allow the peaking of the one side of
the transformer which is still working. In this case, capacitor
values around 200 pf will usually work."
the last option was an article he wrote on the CHRS website.
Thoughts?
[Image: http://www.philcoradio.com/images/phorum...f2dc6d.jpg]
[Image: http://www.philcoradio.com/images/phorum...3b5966.jpg]
I picked up a 39-7 a couple of months ago. decided to start work on the chassis yesterday.
bad news.. it was a mouse-buffet at some point. ate the paper off one of the paper caps! good news is that I managed to get the antenna coil back together (no broken wires, lucky me) bad news is, the bugger ate a hunk out of the primary on the 2nd I.F. (#11 on the schematic)
since this set's IF is 470, I'm wondering if I there's enough adjustment in the padder to use a 455 coil?
I do have a 470 2nd IF donor, but.... it's 2 5/8" long and would span more than half the chassis underneath and cause me to re route wiring and possibly have the center terminal strip in the way. also, it ohms out kinda low on the secondary 1.2 ohms. the primary is @ 19.8.
not sure if this is truly an option or not, but I'm considering the source, Norm Leal. he wrote:
"With IF Transformers use small capacitors
between the plate of the driving tube to the grid of the
driven tube. This will allow the peaking of the one side of
the transformer which is still working. In this case, capacitor
values around 200 pf will usually work."
the last option was an article he wrote on the CHRS website.
Thoughts?
[Image: http://www.philcoradio.com/images/phorum...f2dc6d.jpg]
[Image: http://www.philcoradio.com/images/phorum...3b5966.jpg]
