antenna Tram 1480

[WRVU614]

I have a tram 1480 antenna that I would like to use for gmrs, will shortening the radial to 6.7 inches help the antenna on gmrs channels? OR just damage the antenna?

[Lscott]

7 minutes ago, WRVU614 said:

I have a tram 1480 antenna that I would like to use for gmrs, will shortening the radial to 6.7 inches help the antenna on gmrs channels? OR just damage the antenna?

I would leave it alone. To trim a dual band antenna for another frequency involves more that just shorting the radials.

I would recommend you look for a GMRS specific base antenna. Members here have some very good recommendations they can offer.

[PartsMan]

You could buy on of these instead.

I have had one up for a few months.

Gets me to the horizon from my house.

https://www.amazon.com/Fiberglass-400-470mhz-Connector-Repeater-Transceiver/dp/B08TWN78MM/ref=sr_1_3?crid=2ZXI7NCNZRN7J&keywords=base+antenna+gmrs&qid=1675179467&sprefix=base+anntenna+gmrs%2Caps%2C120&sr=8-3

[KAF6045]

On 1/30/2023 at 9:41 PM, WRVU614 said:

I have a tram 1480 antenna that I would like to use for gmrs, will shortening the radial to 6.7 inches help the antenna on gmrs channels? OR just damage the antenna?

The radials shouldn't matter -- they form a ground plane to reflect the 1/4wave vertical (making a virtual half-wave). Being longer than the wavelength should just mean "more ground" is seen.

Trimming the vertical is going to be the tricky part -- especially if it is a dual-band antenna currently as you may have to trim both top and bottom (presuming some sort of coil in the middle). Heck, you may even have to fiddle with such a coil (adjust spacing) to get it to phase properly.

Probably better to just obtain a dedicated GMRS tuned antenna. Given the short wavelength, you could probably obtain a half-wave dipole and do away with the ground plane radials.

[wayoverthere]

Using a gmrs tuned antenna would be the best option.

That said OP, have you checked that one yet to see how it measures up on GMRS?  my comet gp1 wasn't happy for gmrs (swr of 3+), but others have reported some similar type antennas not being so bad, closer to 1.5:1. It may be usable, it may not, but testing will tell for sure for not much cost besides time, and maybe a swr meter if you don't have one yet (which is good to have anyway) .