Radio problem 1997 ford f-350 powerstroke diesel

[tower512ladder]

All,

Heres the problem, My dept. has a 1997 Ford f-350 p/u with a 7.3l powerstroke diesel when the cold months hit here in pa. the lowband (33mhz)radio will stall the engine when you transmit. I have checked VSWR and power output, both seem to be kosher I have also tried swapping out radios. Im wondering if there is a way RF is getting injected in to the ECM. The truck also has one of those ford engine control boxes with the digital readout. that Box also happens to be mounted near the lowband radio. If anyone has any insight to my problem please let me know im pulling my hair out . Thanks in Advance

 

[key2_altfire]

Seems to me like it could be only two things; RF injection (like you mention) or a temporary amp-starvation of some critical powertrain control component when you key the radio. Might want to connect the radio to a standalone battery, key it up and see if the engine still stalls. If it does, RF problem; if it does not, electrical problem.

 

[rcvmo]

Have you checked the radio with a spectrum analyzer?
The internal Ford ECM uses clock frequencies near the lo-band area.
Try relocating the antenna if possible, re-routing the antenna cable.
Good luck. Loband can do some strange things.
rcvmo

 

[tower512ladder]

Key2_altfire, as i stated in the original posting i swapped radios. I dont think its electrical i checked the TX current and its "normal".

rcvmo, I did not do any testing with a spectrum, because i dont have one readily availible. This perplexes me because the setup has been in the truck since new in 1997 and never a lick of problems till last year (winter of '06). The testing i did was very basic with a bird but nothing looked out of the ordinary. My next step was to try and re route/ install new coax and nmo on the roof. But that is going to be a hassle and was just checking to see if anyone else on the board has had this problem.

Thanks