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Placement of GMRS antenna above an analog TV antenna, Same mast

BQSRIVCA

Newbie
Joined
Jan 7, 2022
Messages
1
Location
Riverside, CA
Looking to put up a 9 foot Comet GMRS antenna above but on the same mast as an analog TV antenna already attached to the chimney. Was wondering if having the TV attenna below the GMRS antenna would hinder the transmissions? And if so, how far away from the TV antenna should I mount the GMRS antenna?
 

Peter_SD911

Scan Sexy
Premium Subscriber
Joined
Jan 16, 2010
Messages
120
Location
Norcal-Socal
It probably won't have an effect on the GMRS TX/RX...However anything over a few watts will definitely have a negative effect on the Off-Air TV reception. The GMRS Transmit will wipe out the TV reception and it could damage the TV. That's just too close...it's brute force the TV won't like. It may take 10ft or more of separation depending on your transmitter power and antenna type. A yagi or a corner reflector might give you some relief...but when stuff is that close then the shear power from the UHF transmitter is going to have a likely negative effect.

Try it on the ground first, test it in your yard and see where the issue begins...then back it off till the interference is gone.

Good luck!
 

G7RUX

Member
Joined
Jul 14, 2021
Messages
408
If you are looking at the GMRS service around 460 MHz then the issue isn't the TV antenna messing with the performance of the GMRS antenna but more the GMRS transmissions upsetting the TV receiver. They are close enough in frequency that a filter will be difficult and the levels in close proximity to the GMRS transmitting antenna are liekly to be enough to damage the TV receiver. The coupling between the antennas is often surprisingly low when mounted as you describe but it is probably not low enough to avoid issues.

In short, I wouldn't recommend installing it like that but try to get some horizontal separation, with the GMRS antenna *behind* the directional TV antenna.
 
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