Comet 2x4 VNA tested for GMRS and MURS

[@SK-rj1ti]

I absolutely agree that each antenna installation is unique. Little things can make a big difference. I have a few different "pre-tuned" 5/8 over 5/8 GMRS antennas (Midland, Nagoya, Wouxun) that I tried to install in three different "sweet spots" (RX-wise) that I had identified around my house. By trial and error I found that each antenna prefers its own spot. Moreover, moving the mounts by an inch could easily produce an adverse effect on the SWR readings.

[@SK-rj1ti]

Another interesting observation along the same lines. I actually have two Nagoya GMRS antennas: one with an SO-239 connector, and one with an NMO connector (both 5/8 over 5/8). I wanted to try both on the same NMO mount, so I got a Tram SO-239 to NMO adapter. To my surprise, the SO-239 antenna with the adapter showed a better SWR than the NMO antenna:) Go figure. Of course, this outcome may have been unique to my install situation:)

[@Soladaddy]

I have done the exact same thing with an adapter and discovered a change in SWR. Even adding/removing a gasket to make a waterproof connection will make a change. Both items changed the electrical length of the element.

[@Soladaddy]

I've had a plan, seems like forever, to get rid of the mag mounts and install NMO mounts to my headache rack on the truck. I know it will skew the radiation pattern and that might be something I can live with. The real question is tuning it. Still on my to do list.

[@kennethschultz6465]

Hey bro i dont know if you are a HAM or "" just a Mudduck"" ther is in basic Open Feeder balanced .. (a part of the antenna) and UN Balanced .. not a part of the antenna.. the first Length is a Factor (ladderline) The second COAX CABEL is not!! if it becomes a part of the antenna somthing is wrong yes i know the old Cutcabel to SWR trick.. but that is making the Cabel not the Antenna 52.OHm The on is a Un ewen 1/4Wave minus Welosetyfactor in cabel.. So Regular COAX is not a part of the antenna Period. If you COAX plugs make SWR .. please buy the bit more expensive PtFe Insulator PL/SO/N (Teflon not Walkitalki Red bakkelit) the PL/SO is not maed to do above 30MHz (but they do) that´s N it goes to GHz+++ like SMA ... and you of corse know that you need atleast a 1/4 Wave from any antenna to surondings to adjust Fair SWR.. so VHF is app 50Cm make a test stand out in the open with the shortest possibel cabel to the antenne foot .. make atleast 1 or 4 radials on 45CM to use as ground. when you use short cabel you mesiur only the antenna .. not the cabel... so it will mesiur same on what ever lenght of coax you use .. and i ofcorse mean 50OHm Coax.. ( if you use 75.OHm sattelite cabel SWR will rais to 1.5 but you can adjust antenna and suddenly you cabel is a part of the setup funny how things are the same until they arent anymore..) using a helical antenna like the Diamond X300 it will work as a filter .. until eatch section is matched .. in the UHF range nice work tho greetings from Denmark

[@Soladaddy]

I might have bad word choice on occasion. While tuning I've used a piece of coax that was not part of the final installation. Once I mounted the antenna with another, longer coax, the SWR changed. It can be considered part of the antenna system and not the antenna itself. Like having an antenna near a metal object will affect SWR, but its not a piece of the antenna. .

[@kennethschultz6465]

@@Soladaddy first the qualety of mudduck rg58 can varie .. cabel is not and newer will be a part of the un balanced antenna.. if there are changes it is due to shitty cabels or kinks in cabel shitty SO PL plugs .. no it is not only metal dry wall wood anything in the same plane as the antenna.. hence the minimum1/4 wave distance to we are talking of surrondings.. Lets not forget .. this is UHF.. kink in cabel changes a lot even a non certified vinkel plug.. who is not in silver or teflon.. will change SWR.. i hawe seen so baad chinesium plugs .. they made 1.5 on VHF and 2+ on UHF just the plug.. what do you think shitty cabel does.. Look For POPE H155 and AIRCELL 7 that is made for UHF ... rg58 is just CHEAP .