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

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

Strange antena terminal function
#1

I recaped and repaired a Philco 38-10. It works fine, except for a non-functioning short wave antena screw terminal. When I hook the 20 ft. antena wire to this terminal, it does no good. However, I get short wave reception when I hook to the AM terminal! The AM terminal also works for the AM band. Everything is conected under the chassis.
For what it's worth, I replaced the 70k ohm resistor with a 39k ohm one, as I understand Philco did after production was underway. (Philco used a 40k ohm resistor, but at 20% tolorance, I see no real difference.) The Rider publication mentions no other accompaning changes. This resistor is part of the short wave receaving circuit, but I can't see how that could cause the disfunction I am experiencing.
If a little solder got down the capacitor terminal when I attached the aforementioned resistor, could that cause such a problem? I presently have no way of testing capacidence. Now that I've got myself thinking about it, I could check that terminal for an open or a ground, but I will wait to hear what the Phorum has to say about this before proceeding further, as it is now fully assembled.
#2

The same antenna terminal is used for AM and SW.

(getting out binder with 38-10 Service Bulletin to confirm) Yup...as with most 1938 Philco models, there are three screw terminals in back: RED, BLK and GND. BLK is connected to chassis ground as is GND. The RED terminal is used as the antenna if you are using a conventional longwire; if you were using a dipole such as Philco's High Efficiency Aerial which was available when the set was new, the red lead of the dipole lead-in connected to the RED terminal and the black lead to the BLK terminal.

It's resistor (11) that was changed from 70K to 40K. Yeah, 39K should be fine as a replacement.

--
Ron Ramirez
Ferdinand IN
#3

Checked the scematic last night when I got home. I don't have a computor there. You are 100% correct. I don't know how I missed that. I guess that's why you're "Mr. Philco".
#4

Well, anyone can make a mistake, which definitely includes me. It's too bad all of the problems that crop up when fixing radios are not this easy to solve.

--
Ron Ramirez
Ferdinand IN




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 1041 online users. [Complete List]
» 3 Member(s) | 1038 Guest(s)
AvatarAvatarAvatar

>