Ham antenna tuning issue

[EricG]

I'm working on my ham rig tonight. I have two antennas I'm trying out. First is a simple 5/8 wave dipole - Diamond M285S Mount is near the middle of my roof rack. Trimmed it up a bit and I'm getting a SWR of 1.2 @ 146MHz and about 1.5 at either end (144, 148).

I also got a short antenna - 1/4 wave 18" Comet SS460SB. Put it on the same location. This antenna is supposed to be "pre-tuned", but when I put the meter on it I'm reading 2.8 @ 144, 2.0 @146 and 1.2 @ 148. Seems way to high for the first half of the range.

Thoughts? No documentation with the antenna, and none on the web as far as I can see. Manufacturer's page is here: NCG Company::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

 

[1911]

There is not much you can do with antennas that can't be trimmed or adjusted, especially since yours needs to be a little longer. If you don't just have to have a dual-band antenna, then just buy a 1/4-wave 2M antenna that can be trimmed exactly to your application, like the Sti-co Flexi-whip. But an SWR of 2.8 is usable, you just won't be pushing a lot of power out when transmitting at that end of the band.

 

[rusty_tlc]

I'd suggest sending it back.


If you can't get a refund or replacement there are a couple of ceramic caps and an inductor in the base that you could play with, assuming you can get it apart without destroying it. You would need and antenna analyzer or network analyzer to measure the impedance as a complex number, or just cut and try until you get it right.