Dead carriers on 40.5 and (rarely) 243.0.

[tomcox]

With a new scanner (BCT15X) set to include 40.5 and 243.0 MHz, I occasionally hear long periods of unmodulated carrier on 40.5, and much less often,on 243.0. They vary in strength from fairly strong to dropping out of squelch, and the signal sounds as if it is a moving source, but could be just fringe reception. My outside antenna is improvised -- a dual-band mobile on a mag mount, on a metal roof.

I am close enough to Ft. Campbell (TN/KY) that they could come from there, but if airborne, could be 100s of miles away. The carrier on 40.5 lasts long enough sometimes that I lock it out temporarily, so the scanner will resume.

Odd, considering the channels are for emergency use only. Somebody sitting on a PTT switch?

Is there a forum with enough life on it near me to be worth posting a notice if it happens again?

Thanks,
TC

 

[bryan_herbert]

40.5 could literally be anything electrical in your house or around town. I cant scan 30-50 MHz because of all the interference.

243.0 at my old apartment in Newhall, CA was interfered with by my Uverse set-top box and a foreign source a block away, never did find out what it was but it created an S9 + 30 carrier signal.

135.0 is often interfered with by gas stations. Dont know if its the pumps, lights, or the video monitors but you can pick up the signal over a block away and when you pull in your signal meter is slammed.

 

[tomcox]

We are in a rural area (nearest neighbor about 100 yds away through a woods), but with many potential RF sources in the house, most of which I recognize from tuning around on 6M - 440. Thing is, the signal strength varies when present, and won't be there at all for days at a time, and then it's back, often several times in one day. It doesn't seem to correlate with any time of day or activity. I haven't had it here for a few days. Guess I need to log it.

 

[tomcox]

To clarify, the antenna is on the metal roof of my house, not on a car.

 

[wtp]

40.5 X 6 =

try some math.
if it isn't your radio then it is something around the house.
then set up a scan with your radio with the antenna out from the lowest to the highest frequency.
i have something in the house that does the 243 thing also.
also to check if it is real try using two different radios with different I.F.'s just to be sure.
my old pro 2004 has no problem with the 243 thing but with my 396T it is hit an miss on different days.
and the 396XT is fine.
and the answer is 243.0

 

[spacellamaman]

it is interesting that this is occurring with a fixed, outside of the house antenna, which if you hadn't mentioned that, would have been my last guess, plus that it is intermittent. while interesting, like the other posters have said, it's likely interference from something. tho my experience has shown less often someTHING, and more often EVERYTHING, with very little exaggeration.

with much sadness, early on i learned amongst a number of other frequencies, 40.5, 121.5 and 243.0 were the most constant offenders and now by default lock them out on everything.