Radio Shack 64" ss whip

[Greatvalue1]

I am running a Radio Shack 64" ss whip antenna on my SUV and I've heard that if you use a pot-belly spring on it, that the SWR's will improve.

RadioShack Stainless Steel Mobile CB Antenna : CB Radio Antennas | RadioShack.com

I've tested it with and without the PB spring and did notice that the SWR's dropped from 1.7 to being flat.

However this concerns me because I know that a flat SWR's reading across the band doesn't necessarily mean that the antenna's performance is improved.

Does anyone know if the spring is hurting the performance of this antenna?

 

[W5LZ]

Really? How long was that spring?
- 'Doc

 

[Shockwave]

The spring will not hurt the performance, its just changing the electrical length of the antenna and providing you with a better match. I would expect you could accomplish the same thing by loosening the Allen screw and lengthening the whip on this base loaded antenna. If that is not an option and you don't like the extra flexibility of the added spring, you could use a quick disconnect adaptor that would add the same length and retain the rigidity.

 

[Greatvalue1]

The spring is the radio shack heavy-duty spring, I think about 4 1/2" or so.

I adjusted the length of the whip with the allen screw till it was at the very end of whip and the SWR's were still reading about 1.7 at best, which would be fine if I didn't care if the antenna was going to fall out driving down the highway.

Usually I see some movement on the SWR meter even when I get a close match with my other antennas, but the needle stayed perfectly flat across the whole band which was my concern.

It does receive and transmit, but with the skip conditions lately it's hard to tell if there is any power loss due to mismatch.

 

[camaro1]

if you think the antenna is short, take a piece of wire and make a 3-4" extension on the top of the whip and see if the swr changes,,

 

[Greatvalue1]

if you think the antenna is short, take a piece of wire and make a 3-4" extension on the top of the whip and see if the swr changes,,

:headbang Why didn't I think of that?

 

[Marconi]

I know nothing particular about this loaded antenna, but I figure the problem might have to do with the vehicle presenting at bad ground plane, and if so...adding length to the radiator is probably not a good idea.

 

[Greatvalue1]

I've used at least four other antennas with great results on this vehicle. I'd think the problem stems more from manufacturing inconsistencies of the antenna.

Bare-bones GMC envoy, by far the quietest virtually noise-free vehicle i've tried. Also tested body panels for continuity.