Antenna SWR question

[Bang Switch]

OK so here's the deal. I have a 2 meter, and a CB in my truck. The antennas are both bottom load, and they are both mounted in the bottom of the steak bed holes in the box of my truck. They are mounted directly through the small drain hole in the bottom. ( I hope that makes sense, it's kinda hard to explain) Any way they are both basically the same antenna with different length stingers. The 2 meter has been in place for a few years and I have had no trouble with it. It was easy to tune etc. No comes the problem, I am trying to tune the cb antenna, and I cant get below 3:1 anywhere on the band. Both setups are the same right down to the brand and length of coax. Any ideas? I'm stumped! Could the radio be a problem? It's a used Pro 510 XL. On the dummy load it showed 4 watts DK and was swinging about 10. Seems normal I think. HELP!!

[Slim Pickins]

Any change to the SWR on your 2m rig?

73, Slim

[Bang Switch]

I haven't checked it lately. I'll have to do that. What are you thinking?

[Slim Pickins]

Just wondering about the 2 reacting with each other. They shouldn't affect each other much though. I have ran 2m and 11m antennas only a couple of feet apart without an issue. Also check the ground of your 11m mount. I have found that HF antennas are way more sensitive to ground issues than VHF antennas tend to be. That could just be a factor of the HF antenna needing a much larger ground plane than the VHF one. Also, did you try your dummy load at the end of your coax that runs to the antenna? Good to eliminate that length of coax as an issue before trying to tune the antenna.

73,Slim

[Bang Switch]

On my last truck I ran the same 2 meter antenna, with a K40 on the other side and that worked ok. But that was a different hf antenna, so the ground plane could be an issue. I OHM'ed the coax but didn't put the dummy load on it. Ill try it. That brings up a question. Is a K40, or Wilson 1000 less susceptible to poor ground plane? Maybe I need to find a way to use one of those. See the reason for the way I mount these is I park in a garage, and I try to keep the total height to a minimum.

[Slim Pickins]

I don't think which 11m antenna you use will make that much difference as long as you are comparing apples to apples. The K40 and Wilson 1000 are pretty much the same design as far as I'm concerned. I would start with dummy loading the coax. I have meter tested coax before only to have it fail on the dummy load with the analyzer.

73,Slim

[Bang Switch]

Thanks for the help slim.

[MDYoungblood]

What CB antenna is it? Slim is right, they should not react to each other. Is this a new antenna or off your other vehicle, asking because if it was tuned and trimmed it might be too short, if new than it might be too long. Check the SWR on 3 channels, 1, 19 or 20, and 40 to see which way the antenna needs to go. If the coax and grounds check out good then it's just a matter of shorting or lengthening the whip.

3's

Greg

[Bang Switch]

Update: I ended up bringing the antenna back, while exchanging it I realized it had a 3 foot whip, but the package said 4 foot, and the new one was 4 foot. I haven't had a chance to put it on yet but I betcha that short whip was my problem. Thanks again for all the help guys.

[MDYoungblood]

That would have done it, no way to add a foot.

3's

Greg