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

High Plate Voltage on IF tube 39-116
#3

(11-14-2014, 08:49 PM)Ron Ramirez Wrote:  Hi Jeff

A look at the schematic indicates 160 volts is incorrect - it should be 260 volts. Notice on the schematic, the plate of the IF tube connects to the screen grids of the 42 output tubes through the primary of the 2nd IF transformer.

Try injecting a 455 kc signal through the control grid of the IF tube. If you get nothing, then use a 0.1 uF cap in series with your signal generator to block the DC from going into your generator, and inject 455 kc into the plate terminal of the IF tube. If you still have nothing, then there must be a problem with your 2nd IF transformer.

Don't forget to check continuity of the 2nd IF secondary (between the 51K resistor and the green wire).

Yes see it now Ron, the red wire out of the 2nd IF to the 42 tubes. Injected the 455 kc signal in in both methods as you had indicated....very distant faint crackling. I will pull the 2nd IF transformer and see what I have. I did get readings in tolerance (primary and secondary resistance) but something may have shifted in reattaching it.

Thank you Ron.


Jeff


Messages In This Thread
RE: High Plate Voltage on IF tube 39-116 - by jeffgniffke - 11-14-2014, 09:15 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 42-390, code 121 speaker
Using a 5W  1.5k  ceramic resistor in place of the field coil and using a 4 ohm PM speaker, I was able to bring the radi...Stevelog — 02:57 PM
Philco 60 Squealing
I have taken out the 2nd IF and found a problem or not. I believe the coils are litz wire. There is a very small strand ...dconant — 02:13 PM
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
Hi Cap'n Clock, Unfortunately, I do not have this radio.  This is a shame because this should be a good performer.  2A5...MrFixr55 — 06:48 AM
American Bosch Model 802 auto radio
I think it would come under either American Bosch or United American Bosch. American Bosch made sets for the American We...Arran — 05:53 AM
trying to identify this wire type
Thanks to all for the feedback. As Arran said, it is probably an older replacement and yes it has a grid cap so I will ...georgetownjohn — 09:32 PM
trying to identify this wire type
It's possible that the red wire, actually a grid cap lead, is a very old replacement, I can't remember seeing a pre 1939...Arran — 09:18 PM
Gilfillan Brothers Car Radio?
Hi everyone,  Special thanks to Joe Rossi for tracking down this obscure radio and thanks to others who took up the hun...Antipodal — 08:15 PM
trying to identify this wire type
Here's one source for your wire of many. Take care and BE HEALTHY! Gary P.S. Can't get the right color you need? I ...GarySP — 06:40 PM
trying to identify this wire type
...and modern wire of the appropriate gauges and insulation V-rating (300V minimum, usually shown right on the wire) is ...morzh — 05:47 PM
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
I have a question about this radio, is there anyone that has access to this radio that has an intact unmolested speaker ...captainclock1988 — 04:28 PM

[-]
Who's Online
There are currently 6645 online users. [Complete List]
» 1 Member(s) | 6644 Guest(s)
Avatar

>