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:
[-]
Recent Posts
1930s Stewart-Warner Tombstone Radio need help identifying model number
UPDATE: I was able to pick up a signal generator on the cheap (amazingly enough) on feebay and I did an IF alignment fol...captainclock1988 — 09:53 AM
Philco 91 Schematic
Hi Rod, The resistor connects to pin 4 and the ungrounded side of block 9. From pin 9 of the RF tube to one side of ...dconant — 09:34 AM
Just got a 49-1613 need to know...everything!
I just found your post. I have this exact same model, and have had it since 1985 when I was 15 years old! I performed a ...MuzzcoVW — 09:11 AM
B&K 1077B no video
Hello Tim, I would if it's a leaky Capacitor So are all 3 of those B- voltages low then ? Sincerely Richardradiorich — 01:55 AM
B&K 1077B no video
I found a schematic and think I have the problem traced down to the minus power supply. I have very low voltages that go...TV MAN — 12:41 AM
RCA 15X
I'd try replacing the bulb first and if that doesn't do it, then change the 35Z5 and see if the problem goes away.NostalgiaRadioTime — 12:28 AM
B&K 1077B no video
Hello Tim, I have that exact unit in my shop too plus a Sencore unit there are times I like one or other !!. Sincerely...radiorich — 11:07 PM
RCA 15X
Everthing goes at once, maybe it's the cold weather, I have had 2 dial strings break and no my little RCA is having dial...Paul Philco322 — 10:26 PM
Philco 91 Schematic
Hi Dan, I can't explain this specific resistor but I have seen the use of a switch to apply B+ voltage to screen gri...RodB — 09:36 PM
6TPZ and 5TPO Radio Help
I suspect it's been repaired before. And I suspect whoever repaired it, wanted to re-use old transistors' pin stubs in o...morzh — 09:24 PM

[-]
Who's Online
There are currently 3985 online users. [Complete List]
» 3 Member(s) | 3982 Guest(s)
AvatarAvatarAvatar

>