1. The PHILCO Phorum
  2. Philco Radio Discussions
  3. Philco Electronic Restoration
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Threaded Mode
Philco 38-7 Oscillation
tludka
Junior Member
**
Posts: 38
Threads: 9
Joined: Jul 2021
City: Franklin State, Province, Country: Wisconsin
#1

8 hours ago
I have let this one sit because of other duties. Now I am back, and I have a couple of questions. I hooked up a Hammond 125BSE audio transformer to a 4-ohm speaker. I receive a crackle and the putt- putt like a bad filter cap. Since the original speaker was not with the radio, I am using a 1200-ohm resistor for the field coil. The voltage checks from the Philco spec are close to the specs except for one of them. The filter caps have been replaced. If I remove the cap lead from the IF 6K7G tube the reading on the plate seems ok and the putt putt stops. When I attach the cap the reading Justs fluctuates and will not stabilize, and putt putt is back. The cap reads a negative 3vdc disconnected from the tube. I have checked all the resistors and replaced the caps. Checked the wiring several times. The 1st I.F. coils ohm out per the schematic but not sure about the mica caps in it. Could this be the problem?
.pdf Philco 38-7.pdf Size: 865.73 KB  Downloads: 6
Find
« Next Oldest | Next Newest »




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 16B Parts
The 16B's in the tombstone cabinet sport a 10 1/2" spkr vs the older cathedral sets which uses an 8". The p/p ...Radioroslyn — 12:58 AM
Philco 38-7 Oscillation
I have let this one sit because of other duties. Now I am back, and I have a couple of questions. I hooked up a Hammond ...tludka — 11:16 PM
Philco 38-7 Speaker
I know that when I first started working on this radio, I did not even have a speaker. Once I finally found one it was n...tludka — 11:00 PM
Philco 60 Squealing
I seem to remember eliminating a squeal by changing the IF frequency by a few KHz. Not that you should put too much tru...fenbach — 08:48 PM
Philco 42-390, code 121 speaker
These speakers pop up on eBay regularly, even if at bloated prices. Honestly, have not seen many parts on swapmeets.morzh — 08:38 PM
Philco 38-7 Speaker
The put-put is not like the speaker problem.morzh — 08:29 PM
Mission Bell Model 19A Car Radio
Hello everyone,  As mentioned in my last post I was going to see if the vibrator / rectifier section could be persuaded...Antipodal — 08:21 PM
Philco 60 Squealing
Wondering if I did it backwards. If a coil was wound backwards, the oscillator would not work at all. Old school...Chas — 07:23 PM
Philco 38-7 Speaker
4-ohm speaker. Black, Green leads.tludka — 07:00 PM
Philco 42-390, code 121 speaker
#87 on the schematic.  This radio had a 8" Zenith  speaker attached to it when I got it. I do don't know the hist...Stevelog — 06:39 PM

[-]
Who's Online
There are currently 4791 online users. [Complete List]
» 1 Member(s) | 4790 Guest(s)
Avatar

>
  1. The PHILCO Phorum
  2. Philco Radio Discussions
  3. Philco Electronic Restoration