Need to "reset" tune on Comet CA-2x4SR antenna

[AC0X]

Anyone have info on how to adjust the elements of a CA-2x4SR? know this has sort of been discussed before, but the solutions have all been "move the antenna" or "try a different mount", and my issue is that I've picked this antenna up from someone that I suspect has already played with the elements. If possible, I'd like to find some sort of reference that either instructs how to reset the antenna to factory setting, or information that tells me which of these elements to adjust for SWR. Thanks.

 

[AK9R]

NCG is the U.S. importer of Comet antennas. I'd start with them: contact us | Comet Antenna

 

[K7MEM]

There should be only one adjustment on that antenna and that is at the base of the bottom element. Here is a link to the Operating Manual, but it doesn't provide factory lengths. However, if you have a SWR meter, you should be able to being it into adjustment. Something like a Nano VNA would be even better for adjustments. Note that they only specify a SWR that is less than 1.5:1. So if you get in that range, your good. What SWR readings are you getting now?

 

[AC0X]

Thanks @K7MEM and @AK9R. I contacted NCG and got a response from Comet President Mick Stwertnik. He told me all the elements should be bottomed out, but making that adjustment didn't help (about 4:1 at the antenna on a metal sheet ground plane on both 2m and 70cm). It's a ~15 year old antenna someone just gave me for free so nbd. But when I took a pic of the sun-faded label and upped contrast on the image on my phone I found out it's an old SURMEN!! So into the trash it went and I ordered a REAL SS-680 and CM-5M from DX Engineering/ (Yes I know "Mag mounts phooey! Drill that hole!!" but it's a new vehicle with a sunroof and a headliner to take down on the inside and it seems neither I nor anyone I can find seems to want to take that project on my single non-fleet vehicle)

Thanks to all

 

[prcguy]

Most sun roofs slide to the rear with the area between the front windshield and sun roof being mostly free of any obstructions. You can usually pull the rubber door trim off from the upper front windshield to just pass the sunroof and lower the edge of the headliner a few inches, then you should be able to stick your hand up in there a ways to feel for any obstructions. If it looks good (like no air bags) drill your hole and fish the coax to the opening you just made and route it down the window pillar and off to your radio.

 

[pandel]

Most sun roofs slide to the rear with the area between the front windshield and sun roof being mostly free of any obstructions. You can usually pull the rubber door trim off from the upper front windshield to just pass the sunroof and lower the edge of the headliner a few inches, then you should be able to stick your hand up in there a ways to feel for any obstructions. If it looks good (like no air bags) drill your hole and fish the coax to the opening you just made and route it down the window pillar and off to your radio.

That's good advice. I watched the Motorola shop do exactly the same thing when they did the NMO install on my SUV.