choosing an antenna for my new 2m ....

[gary in ohio]

The Hustler G7 is a base antenna, isn't it? Seems that might be a durability issue off highway?

I am showing my age, There is a G7 base and at one time the g7 mobile. Its now called a CGT-144, Its the big 7ft 5/8 over 5/8's antenna.

 

[jeffryscott]

thanks everybody.

Found a whip antenna locally at a little shop - it's a Larsen lookalike, Tram, and mounted it to the driver's front with the L bracket and now need to trim it. It is 5/8 wave. It is silver though, can I paint it black without harming reception?

It seems the common frequency range I have seen is 146.xxx, is that pretty standard? The shop gave me measurements for the antenna to trim for SWR, but before I do any cutting, just want to double check.

Thanks again,

Jeff

 

[Pskhaat]

146.xxx, is that pretty standard?

The Ham frequencies on 2m are 144-148MHz. Some info here:

http://en.wikipedia.org/wiki/2_Meters#Sample_band_plan

As far as trimming, is it a proper 2 meter Amateur band antenna? If so, you may not need to.

 

[jeffryscott]

It is a proper 2m antenna and they gave me a list of the optimum height for the frequency ranges (47.25 inches for the 146.xxx range, or thereabouts). The two fellows seemed like proper HAMS and I think the trimming, etc .. is for optimal performance (they seemed a bit nerdy, no offense intended). Antenna is a Tram 1151 (53-inch whip).

I won't do any trimming until I get the radio installed and get it all set up, and by then, hopefully I'll be a better informed consumer, vs. the wannabe I am now.

But the important thing, can I spray it black?

 

[articulate]

But the important thing, can I spray it black?

Several of my buddies spray painted their antennas black, no big deal.


I know, I know . . . a third-person account retold on the internet. Take it for what it's worth.

 

[jeffryscott]

Several of my buddies spray painted their antennas black, no big deal.


I know, I know . . . a third-person account retold on the internet. Take it for what it's worth.

Good enough for me.

 

[DaveInDenver]

It is a proper 2m antenna and they gave me a list of the optimum height for the frequency ranges (47.25 inches for the 146.xxx range, or thereabouts). The two fellows seemed like proper HAMS and I think the trimming, etc .. is for optimal performance (they seemed a bit nerdy, no offense intended).

There may be a range of suggested lengths, but each installation is different. The length you end up with will be determined by the SWR you get. Anything else is a guess.

 

[jeffryscott]

So before I do any adjustment, I really should use an SWR meter on it to tune it, correct?

 

[DaveInDenver]

So before I do any adjustment, I really should use an SWR meter on it to tune it, correct?

Yup, best to put the mount on, run the cable and mount the whip all like you're more or less gonna leave it. The length and routing of the cable, the location of the mount on the truck, these thing affect the VSWR of the antenna. Once you're satisfied that your antenna system is about right, then hook up the meter to the radio and coax feed, use the lowest power setting and see what you get. It's best to be in an open area, minimal buildings and stuff around. An open parking lot works well.

Start with the simplex frequencies, key the mic and announce your call sign and what you are doing. Something like "This is KE0ZZZ testing a new antenna for SWR on 146.400." You might get a response, probably not. But treat your antenna test like a regular transmission, so call sign, frequency, etc. If the SWR is around 2:1 or below between 146.400 and 147.585 (typically the lowest and highest 2m simplex frequencies on most band plans), you are close enough to test a lower frequency repeater at around 144.510 or whatever the lowest repeater you have available. Follow good repeater protocol, say your call sign, what you are doing, etc. Testing on a repeater input frequency will likely get some sort of response and be mindful not to interfere with a conversation and spend only a minimal amount of time on the air.

Go back to the 146.400 simplex and do your tuning there. You want the SWR at 144 higher than the 147 to start. This means the antenna is too long. Cut the whip down in small increments, 1/8" inch or so at a time. A perfect antenna is 1:1, but in reality anything like 1.2:1 or 1.3:1 is pretty good. I personally look for something 1.5:1 or lower and don't spend much time tinkering with it after that. Once you have it good at 146~147MHz, go back down to the lowest repeater and give it one more check at ~144.510. Most likely the antenna at 146 will be very close at both 144 and 147, most ham antennas have pretty good bandwidth.