Transmitter Proximity

Status
Not open for further replies.

TheFlyingPilot

MPSCS Newbie
Premium Subscriber
Joined
May 18, 2017
Messages
73
Location
Frankfort, Michigan
I'm operating my BCD325P2 in a pretty low reception area, and I notice one of my P25 sites is showing 5/5 bars. I hold the frequency (853.800MHz) and drop the squelch. I hear through the static "You're... CBS Sports Radio...", and I suddenly realize that I'm listening to voice from an FM channel. I did some research and found that the original FM channel is 92.3 FM, which is being transmitted from a tower approximately 5 miles from my receiver. So basically, my scanner is receiving voice bleedthrough from a channel almost 800MHz away. Why is this happening? Is it because of my proximity to the tower or what? (If you want to look at the locations I live in Elberta, MI and the tower license is KQJ233)
 

RFI-EMI-GUY

Member
Joined
Dec 22, 2013
Messages
3,969
This isn't actually annoying to me, I'm just curious as to why it's happening.
It is probably a spurious response within your receiver. try the IF shift (IFX) selection if your model has it. Basically what is happening is that a combination of the local oscillator frequency and the harmonic of the 92.3 station are mixing and falling within the IF frequency. The cure is a bandpass filter or an FM notch filter.
 

chief21

Member
Premium Subscriber
Joined
Mar 2, 2004
Messages
1,312
Location
Summer - Western NC; Winter - Tampa Bay FL
Depending on the design of the receiver, images of received signals can be created far from the actual frequency. Generally, the stronger the signal (or closer to the source), the more evident these images can be. A very strong signal could also simply be overwhelming your receiver. In your case, the source is relatively close and probably very powerful (perhaps 50,000 watts).
 
Status
Not open for further replies.
Top