Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Philco 39-7C Restore
#16

A little more work today. I got the first IF transformer back together after replacing the wiring going to the 78 tube grid cap. That was the only one that was bad. The faulty antenna transformer is next. On it, the secondary (between pins 3 & 4) is open. I managed to get it off the radio without too much trouble but as I mentioned earlier it has a fish paper outer covering on it. As far as I can tell the cover does not have any wiring in it but I can't really figure out what it would have been for. Any thoughts on that?

[Image: https://www.dropbox.com/scl/fi/9ibrzwrc3...az93&raw=1]

With a bit of snipping and slicing I was able to get the paper cover off.

[Image: https://www.dropbox.com/scl/fi/n9oayjsl3...pzds&raw=1]

The entire set of windings are covered in wax so its difficult to see anything but nothing particularly out of the ordinary pops out. I gave reheating the #3 and 4 connections to see if that might create continuity a try, but it did not help. I can see the two sets of windings, a 1/4" band of thin wire coil at the upper end of the image and another that covers most of the transformer tube which appears to be of a thicker wire.

I'm thinking my only choice here is to melt off the wax to try and see if there is an obvious break somewhere or just look for a replacement antenna transformer. I did rewind a coil in another radio but it was only a primary on the outside of the transformer and only had about 13 wraps, pretty easy. This looks a lot more intimidating.
#17

I've melted off much of the wax on the antenna transformer and had a good look at the two ends of the secondary winding (the larger, crosshatched winding).  Both looked to be intact.  Some additional remelting solder on the lugs did not fix the open winding. The winding pattern of the secondary is very complex and I was not even able to easily unwind it so I've set the entire project aside for now and will look for a replacement antenna transformer.  I think it will be awhile before I get back to this.  It may be one of those parts sets that sits on the shelf and is slowly scavenged. 

[Image: https://www.dropbox.com/scl/fi/vjfs9f5on...frfx&raw=1]




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Restoration of the Canadian General Electric A-87
Ok.... In the fourth year of the war, I still decided to return to an active hobby. For more than three years, I did not...RadioSvit — 10:43 AM
Philco 37-116 Cabinet Repair
You'll probably have to get quite a large amount of wax filler, those are some big gaps, and both sides. Nice summer pr...RodB — 10:38 AM
Philco 37-116 Cabinet Repair
Hello everyone. I completely agree with Richard and Dan - in this case, without replacing the veneer, only a wax filler ...RadioSvit — 10:07 AM
Philco 37-116 Cabinet Repair
I have used Timber Mate Timber mate is a grain filler  . You can get it in different colors,so it will be close to...Dan Walker — 09:51 AM
Help with Supreme 599
The 300 ohm line adjustment is used to set the primary of the transformer to a nominal voltage for any line voltage from...DaleHCook — 09:22 AM
Philco 37-116 Cabinet Repair
I think Arran is correct about the substrate expansion. I'm going to give the colored wax a try.dconant — 08:11 AM
Philco 37-116 Cabinet Repair
Hello Guys, What I would do is get  colors of wax filler and fill in the void ! Sincerely Richardradiorich — 12:41 AM
Philco 37-116 Cabinet Repair
It looks to me like the structure under the veneer may have expanded from humidity cracking the veneer on the surface. W...Arran — 09:42 PM
Help with Supreme 599
Iam only getting 4vac out of the tranny For the 80 filament. The line rheostat Looks fine and the tranny is getting 11...daveone23 — 08:45 PM
Rogers Majestic R-646
Transformers rewind? It's very easy! If you don't have round eyes  8-) Vlad95 — 01:55 PM

[-]
Who's Online
There are currently 1320 online users. [Complete List]
» 1 Member(s) | 1319 Guest(s)
Avatar

>