aapaws

I started to play around a little with the length. Got the swr down to 1.35 from 1.74 on reg channel but on repeater channel it went up from 1.11 to 1.49 that was on antenna 4505s whip. On the 4505ngps I got it down from 2.27 to 1.74 on reg channel and 2.39 to 1.65 on repeater channel. Don’t think I can tune any better. I’m leaving the 4505s whip antenna requires ground plane but gets best signal swr. Could it be possible that the metal fenders could be acting as a reflective ground plane even though the mount is 1.5” higher than the fender? sorry did not take pics of the 4505ngps signal. thanks

I will try shorting it just a little to see what happens maybe a 1/8 inch just to see. the models are https://theantennafarm.com/shop-by-categories/shop-all/mobile-antennas/300-512-mhz-uhf/no-ground-plane-antennas/8346-pctel-maxrad-muf4505ngps-detail https://theantennafarm.com/shop-by-categories/shop-all/mobile-antennas/300-512-mhz-uhf/high-gain-antennas/8345-pctel-maxrad-muf4505s-detail https://www.arcantenna.com/products/trab4503-m2m-400-490-mhz-black-low-profile-omni-antenna https://www.arcantenna.com/products/trab4500n-m2m-400-490-mhz-black-low-profile-omni-antenna That are the exact antennas. The trab4500n is total useless and the 4503 is the best for the ghost antennas. The other whip antennas are the ones above that match the printouts with the tune sheets. I thought this would be of help with the confusion. I will tune them again just a little when I get the new meter just to see. I also ran a separate 10 gauge ground wire just to see if it would help and it did very little. Thanks for the quick response.

Ps I’m still waiting on the NanoVNA the one I order was 3 weeks out.

Sorry for gettiting back so late. I just received new antennas cut and tuned for 462 printouts attached. The 4505ngps has a swr of 2.27 on channel 16 and repeater channel of 2.39. On the ground plane antenna 4505s its swr 1.74 on channel 16 and on repeater channel 16 its 1.11. With the printouts attached would it be worth it to try to trim the antennas anymore. I am still on the fence if I should try another swr meter because the antennas have been tuned to the frequency as far as I can tell. It’s also funny to me that the Mount I’m using I would have thought the no ground plane antenna would work better. I wondering if the fenders I’m using is causing a problem they are metal. thanks

I'm going to call Pctel on Monday and ask them about the spring and what they think about the issues. Just seemed funny that the one ghost gets crazy good results 1.1 and the other I would not use over 3+ swr. I was going to bite the bullet and order the bird 43 seemed like it gets good reviews. May try the MFJ-847 first its a lot cheaper. I even ran a separate ground wire to the mount just to see if that was some of the problem but no change. I want to say thanks for all the help this is new to me. I thought the radio programming would be the hardest and its ending up being the antenna.

Thank you for the quick responses. I up loaded the pics for the low power as suggested had to program the radio first for low power only had programed for full power. Attached pics. The 1.14 swr tied to 4503, 3.82 tied to 4500n, 4.36 tied to 4505ngp. All test done away from everything. I also ordered the NanoVNA hopefully be in Wednesday/Thursday next week. The 4505 says to cut the length to roughly 11". At that size it still was over 8 swr as it is now its cut down to 7.25" which is way to small. I order a new whip for the 4505 and we will see with the NanoVNA before I start cutting again. Also thinking about ordering another gauge this time maybe something better.

Sorry Could not test yesterday it rained all day looks like I have water front property now. I had retested this morning and still got the high swr. I cut and retested best I could get was 2.45. The only equipment I have for this is the one swr meter. Could you tell me if there is a better one because I don't know if I trust this one? The radio is a 45 watt radio. The ghost antenna constantly gets the best results. Always 1.01 to 1.12 no matter how many times I switched. Pretty much know I screwed up the other antenna because I cut it to small now its going in the opposite direction up. Live and learn I'm new to this but the radio works so at least I programmed that right. Thanks

Forget about the last post on not giving me the frequency I was not holding the button long enough to get it to input. The numbers still stand on the swr with what I posted above.

I just noticed in the pic that its not giving me the frequency is this common on this gauge?

Sorry for getting back so late I was on a small road trip. I used the ghost antenna with a 1.0 swr for most of the way but switched to the 4505ngp antenna the taller one not the ghost antenna which had the original 1.01 swr when I got to the mountains. That antenna was swinging in the wind a lot for the trip. When I came home I tested the antennas outside. The ghost antenna still gets a perfect signal and the taller antenna now gets an extremely high swr of 11.46. I did not even get to use the radio at all I was on a solo business trip and I only picked up a occasional signal. It was fine before the trip with an 1.01 also. Now it’s extremely high. I understand that it was moving but all was tight and I did not hit anything with it just removed to switch antennas. I starting to think maybe my gauge is bad but the ghost antennas have never changed in the swr range. The 4503 was always 1.01 to 1.03 every time but does jump to 2.05 for the repeater stations and the 4500n ghost antenna was always 2.95 to 3.45. The only antenna that seems to have changed is the one that can be adjusted. I will try again tomorrow to see if the connections are loose on the Allen heads if not I am hesitant with cutting it because of the original good swr reading. I don’s understand how it could have that big of a swing unless the antenna moved or went bad somehow or the surecom is bad? I never ever got a reading that high on any of my original test. The radio does work great with the smaller 4503 antenna tried out at home with some friends but I figured I would use the larger one for more range and switched when I hit the first rest area gas station. Glad I did not use it if the swr is true.

forgot to attach to picture

Just got home and rechecked like suggested and the cable is bad. The rfmax cable gives the high swr but the larsen gives the best signal. Also thought is was funny that the ghost antenna is giving me a better swr over the almost 31" antenna. larsen and laird trab4503 for the win. thank you for the help.

I just finished loading the GMRS channels into the radio and decided to do a bench test for swr. The cable that I used for the bench test was a Larsen NMOKHFCXMPL with a Laird trab4503 antenna. That's the pic with the 1.91 swr reading bench test inside. Go to the jeep and hook up the radio attached to a RFMAX, RNMOV-195-SUM-C-17I cable and used the pctel muf4505ngp antenna check the readings and get 6.86. Switch to a trab4500n antenna no ground plane needed and get 4.71. Take the radio out go back to the bench and repeat with original Larsen cable and 4503 that needs a ground plane again and get the same 1.91 reading. Remove the rfmax cable from the jeep and replace with a Larsen cable same as the bench test above and repeat the process this time the swr with the 4505ngp is 1.01 and with the trab4500n different antenna from bench test I get 2.95. If I switch the trab4500n no ground plane for the trab4503 I get 1.45. The mount used is on the passenger side of the jeep 2nd bolt Topsy Jk mount. I am confused with this so the question is how does a non ground plane antenna work worse and the ground plane antenna work the best? I was under the impression that the fender mounts did not have enough for a ground plane. Also the cable being that far off with swr I'm glade I did not try to cut the antenna. Has anyone else had this happen to them? Thanks