Comet CA-F72GF 440-480 5.5dBi Antenna

[WRFP399]

So I just got this from Amazon for about 100 bucks. I won't get to test it real world for a bit but I did some SWR reads on it using a Nano VNA.

The first read was it straight out of the box...appears usable. The antenna appears very forgiving with tuning. I cut it three times sneaking up closer. The lower element ended up getting trimmed to 207mm and the upper element was trimmed to 324mm. This was right on where the cut chart said to. 

 

I tuned it for 462mhz as it will be used for a repeater. The SWR shows nearly 1:1 at 462mhz. At 467mhz it shows just under 1.1:1. I could probably cut a bit more off based on the curve and keep both very low but I chose not to.

 

The sideways photo is the SWR as it sat from the factory.

 

 

[gman1971]

Most of those antennas develop water ingestion due to the foam absorbing humidity. I've had multiple antennas like that, that within a few months developed super high SWR. 

Hopefully you have better luck than I did.

G.

[WRFP399]

Welp. I threw it out real quick. Attached it to the corner of my wood deck rail on the end of 10 feet of RG58. Tried it on a spare RT97, didn't work well. Hooked it to a Motorola CM300 set at 5 watts still not working worth a damn. Very low reception and transmission signals.

 

A N9TAX slim Jim in the same spot works well with 16 foot of RG58.

 

I dunno. Guess I need to try one of those meters that tests the antenna with power running through it?

 

Do you have any recommendations for a similar sized antenna? Trying to keep it around 3 foot in length.

[gman1971]

https://www.ebay.com/itm/224684607008?epid=1800453427&hash=item34503f0620:g:VfgAAOSwdh9gAbBL

[WRFP399]

Thanks for the suggestion. I decided to go with a Liard FG4603.

 

Still want to figure out what the deal with th Comet is.

 

[gman1971]

FG4603 perfect as well. Good choice.

[Flameout]

Would the Laird 4500 or 4603 be a better choice over the Comet CA-712EFC?

[gman1971]

Yes, I think so.

I've had an FG4500 up for 2 years in freezing winters and scorching summers, going strong without a single hitch. The FG4603 is basically the same antenna construction with higher gain (and realistic gain)

G

[WRFP399]

Picked up a 20 foot length "cheap" KMR-400. LMR400 knockoff. Had decent reviews.

Hooked it up to the comet and the RT97. Set the RT97 to low power and took a drive while connected into the myGMRS mountain hub. Used a 1 watt HT to talk back. 

 

Talked with a Justin from TX who reported it sounded good. It was by no means a great test but it was working much much better vs the other night.

 

I might use this Comet installed in the attic of my house where it is protected.