Tram Model 1191 Glass Mount Antenna-Help

[PaulC]

Hello.
I am a relatively new ham, and I have an FTM500DR installed in my aluminum-bodied F-150. I installed the Tram, and it came with a 17 ft coaxial cable. I receive 70cm pretty well with a SWR of less than 2.
The problem is on 2 meters. I cannot get it below 1:4. I do not need all 17 feet of coaxial, but maybe 4' at best.
Can the cable be tuned to bring me under 1:2 for 2 meters?
All suggestions are welcomed.

 

[Crawdad]

Welcome to the forum Paul and to Amateur Radio.

The antenna is tunable so I wouldn't go chopping your coax just yet. A 1.4:1 VSWR is just fine and personally I would leave it alone, but if you feel the need then tune the antenna. The difference in your transmitted signal by getting down to <=1.2 is minuscule and would never be noticed by you or the station on the other end.

7 3 and enjoy

 

[w9cll]

Glass mount antennas are notorious for having high swr's, I had an Antenna Specialist one in the 90s. I was never able to get the swr below 1.6. I ran with it that and there were no issues but I will say then do not perform well and are highly directional.

 

[nomadradio]

The original 27 MHz glass-mounted antenna from the 70s had a tiny metal slide that protruded from the bottom of the whip's mounting foot. It was held in place by a setscrew. Moving this metal tab in and out would get the antenna's resonant frequency centered to channel 20. A slug-tuned coil inside the plastic "matching" box that was on the inside of the windshield would tune for best match.

Haven't tried to use the present-day 2-meter version, but I would start by checking SWR across the band to see the frequency where it's lowest. Might only need to get the resonant frequency bumped up or down a bit.

73