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Ford F-1540 Questions
#1

I am trying to get a F-1540 back operable for a friend with a 1938 Ford.  The radio came separately with the car purchase and the previous owner had no status on the radio condition.  Cosmetically it is pretty decent shape.
I am a semi retired technician and worked with high power tube transmitters for several years but I have been away from that era for a long while.  I have been reading till my eyes bleed on this site and took the good advice of changing out all the dripping wax caps.  I have recently dealt with the power supply  4/8 uf can by putting a couple of caps on the bottom side … I don’t like the aesthetics but it brought the B+ voltage to about 211 volts.  Not sure if that is correct as I don’t really see any documentation with typical tube voltages.  I’d have changed a few resistors also that were off center value by quite a bit.  
Today I was able to half step and inject 260 kHz in the If producing a nice clean tone.   I eventually got to the point of injecting a 1MHz signal at the grid of the first RF tube and tuned around a bit eventually finding the signal a few hundred KHz off the dial indicator.  The sensitivity I am seeing is around -50 dBm and that is not real crisp.   I can inject into the antenna port also with a bit more loss.

As I am just getting started in this extracurricular activity I don’t have a supply of tubes but may order a 78 and 6A7. I am pretty encouraged about being able to jam a signal through now it may be just a matter of getting it stronger and cleaning the fuzz out.  

I am probably not knowledgeable enough to ask the right questions yet but there is a couple that come to mind.   
What kind of sensitivity should I expect out of this auto radio?
I’m pretty convinced the dial is not tracking right so maybe an alignment would help?  Would a front end tube swap be useful before I went hog wild with a tuning tool.   
Another symptom is the radio seems to produce a good amount of irritating buzzing but when I get the signal tuned in it reduces a lot but a but fuzzy.   The IF to Audio stages were real clean sounding.

I would welcome any comments from the brain trust here as to my next steps.

Regards,

Bill


Messages In This Thread
Ford F-1540 Questions - by F-1540 - 12-26-2023, 10:55 PM
RE: Ford F-1540 Questions - by RodB - 12-27-2023, 12:25 AM
RE: Ford F-1540 Questions - by Tim Tress - 12-27-2023, 12:44 PM
RE: Ford F-1540 Questions - by Chas - 12-27-2023, 01:55 PM
RE: Ford F-1540 Questions - by morzh - 12-27-2023, 03:19 PM
RE: Ford F-1540 Questions - by Chas - 12-27-2023, 03:35 PM
RE: Ford F-1540 Questions - by morzh - 12-27-2023, 03:50 PM
RE: Ford F-1540 Questions - by F-1540 - 12-27-2023, 06:18 PM
RE: Ford F-1540 Questions - by morzh - 12-27-2023, 07:11 PM
RE: Ford F-1540 Questions - by David - 12-27-2023, 07:27 PM
RE: Ford F-1540 Questions - by David - 12-27-2023, 07:29 PM
RE: Ford F-1540 Questions - by Chas - 12-27-2023, 08:59 PM
RE: Ford F-1540 Questions - by F-1540 - 12-28-2023, 11:10 PM
RE: Ford F-1540 Questions - by Chas - 12-29-2023, 12:30 AM
RE: Ford F-1540 Questions - by David - 12-29-2023, 03:49 PM
RE: Ford F-1540 Questions - by F-1540 - 01-13-2024, 06:04 PM
RE: Ford F-1540 Questions - by RodB - 01-14-2024, 10:57 AM
RE: Ford F-1540 Questions - by F-1540 - 01-23-2024, 02:28 PM
RE: Ford F-1540 Questions - by RodB - 01-23-2024, 05:54 PM
RE: Ford F-1540 Questions - by F-1540 - 01-23-2024, 06:33 PM
RE: Ford F-1540 Questions - by fenbach - 01-24-2024, 12:05 AM
RE: Ford F-1540 Questions - by radiorich - 01-24-2024, 09:38 AM
RE: Ford F-1540 Questions - by Chas - 01-24-2024, 01:28 PM
RE: Ford F-1540 Questions - by F-1540 - 01-27-2024, 10:00 AM



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