High SWR and reflected power using repeaters

[jsouth]

Recently installed a Browning BR-6146 in my attic. I used 1/2 heliax 55 feet and Belden 9914 as the jumpers to and from the heliax. All connectors are N except at the radio(PL-259 for Midland MXT-400). SWR is great across the board (never more than 1.07), until I get to repeaters. Then the SWR jumps to 1.35 and almost to 1.95 on higher power output applications. The reflected power is high as well.

My question is: is this a result of the installation being in an attic? Or is this Browning some type of Jpole that needs ferrite magnets or a coil of wire at the antenna to remedy?

[tweiss3]

What frequencies are you testing your SWR at?

[jsouth]

Gmrs - 467 and 462 MHz. 467 is where the readings are high.

[marcspaz]

The antenna should work fine. Do you have asphalt shingles? Some folks have metal roofing and/or trim and overlook that. Especially flashing materials and face boards.

 

Make sure the antenna is at least 6 feet away from any metal or electrical lines. That includes any metal outside on the roof and side of the house.

[jsouth]

The antenna does seem to work fine. I just find it odd that I got that result. I have asphalt shingles, no metal on the roof, and a UHF TV antenna that’s about 10 feet away. It’s also mounted very high as I have a steep roof pitch that allows me to get it up as high as I can reach. I just like knowing how and why things work. Thank you for the input.

[Jones]

Try putting some toroid chokes on that 9914 jumper at the base of the antenna.  It sounds like it is working fairly well anyway.