Newbie intro and questions

[Delivers1234]

Its a 102 whip. i tried with spring and without. i grounded mount to chassis with wire. same values of 2.3 to 2.5. the wire runs off the trailer rack (hitch) in a grommet next to trailer wires and under carseat to front.

ill head to ham outlet tomorrow.

 

[jonwienke]

Your scooter rack is trying to be part of the antenna's ground plane. Not only does it have to be electrically bonded to the car body, but all parts of it have to be electrically bonded together as well. The floor mesh, the support frame, and the antenna mount all have to have good electrical connections to each other as well as to the car body. You need clean metal-to-metal contact, as well as weatherproofing sealant to prevent corrosion, especially if you live anywhere near the ocean and there is any possibility of exposure to salt spray..

 

[Delivers1234]

Your scooter rack is trying to be part of the antenna's ground plane. Not only does it have to be electrically bonded to the car body, but all parts of it have to be electrically bonded together as well. The floor mesh, the support frame, and the antenna mount all have to have good electrical connections to each other as well as to the car body. You need clean metal-to-metal contact, as well as weatherproofing sealant to prevent corrosion, especially if you live anywhere near the ocean and there is any possibility of exposure to salt spray..

Hi. Here r the pics.

 

[jim202]

You didn't mention if the spring you tried using was a new one or an old one. The reason i bring this up is there should be a flex jumper made from copper braid and will be silver plated to reduce corrosion. the only way to tell if the braid is good is to bend over the whip and spring and look inside the spring. It will take some real effort to bend the whip over enough to be able to see between the spring coils.

On older springs, you will probably find the jumper broken or in real bad shape from corrosion. The only way to solve a bad jumper is to replace the spring.

As for your SWR issue, you can try taking a couple of real small hose clamps and try adding an extension on to the top of the whip by maybe 3 inches and see what the SWR does.

You may just have an issue with where and how the mount is for the antenna. I had to mount a low band antenna on a cement mixer for a company many years back. No matter what length the whip was, I couldn't reduce the reflected power to a reasonable number. I was using a telescoping antenna so changing the length was easy. Where I was forced to mount the antenna and the metal from the cement mixer just wouldn't allow a good match for the antenna.

 

[Delivers1234]

You didn't mention if the spring you tried using was a new one or an old one. The reason i bring this up is there should be a flex jumper made from copper braid and will be silver plated to reduce corrosion. the only way to tell if the braid is good is to bend over the whip and spring and look inside the spring. It will take some real effort to bend the whip over enough to be able to see between the spring coils.



On older springs, you will probably find the jumper broken or in real bad shape from corrosion. The only way to solve a bad jumper is to replace the spring.



As for your SWR issue, you can try taking a couple of real small hose clamps and try adding an extension on to the top of the whip by maybe 3 inches and see what the SWR does.



You may just have an issue with where and how the mount is for the antenna. I had to mount a low band antenna on a cement mixer for a company many years back. No matter what length the whip was, I couldn't reduce the reflected power to a reasonable number. I was using a telescoping antenna so changing the length was easy. Where I was forced to mount the antenna and the metal from the cement mixer just wouldn't allow a good match for the antenna.

It's a new one but a light/ medium type. It whipped so much that I took it off. I need to get a thicker one.

 

[gewecke]

It's a new one but a light/ medium type. It whipped so much that I took it off. I need to get a thicker one.

Why not a roof mount antenna, such as the Larsen Nmo 27 ? You would get great performance and even decrease the amount of coaxial cable. 73, n9zas

 

[mmckenna]

I'd agree. A 102" whip with a less than ideal ground plane isn't going to work any better than a properly installed NMO-27 with a better (but still not perfect) ground plane. Getting the antenna up and above the vehicle body is going to get you better performance 360º around the vehicle.

 

[Delivers1234]

I'd agree. A 102" whip with a less than ideal ground plane isn't going to work any better than a properly installed NMO-27 with a better (but still not perfect) ground plane. Getting the antenna up and above the vehicle body is going to get you better performance 360º around the vehicle.

Could let me know if the nuts and the washers and the plastic one are correct? In the pic?

 

[mmckenna]

Could let me know if the nuts and the washers and the plastic one are correct? In the pic?

Looks correct.

If you have a multi-meter or a continuity tester, there are a few tests you can run to rule out some common issues:

Disconnect the coax from the radio. Leave it connected at the antenna end, with the antenna installed.
Check for continuity at the radio end of the coax between the center pin and the outer shield. There should not be a connection between these two. If there is, stop and fix. (infinite ohms)

Check for continuity from the outer shield of the coax (at the radio end) to the vehicle chassis. There should be continuity if your antenna mount is correct. If there isn't, you need to fix this. (0Ω or a low number. A bit of resistance is OK)

Check for continuity from the center pin of the coax (at the radio end) to the vehicle chassis. There should not be continuity if everything is correct. If there is, stop and fix. (infinite ohms)

If you get through all that OK, your coax and connectors are probably OK. When doing the tests at the connector ends, try wiggling the coax cable around a bit where it enters the connector. This is often where the issue lies.

Last test for now, and you'll need some help with this:

Check for continuity from the center pin of the coax connector at the radio end to the antenna whip. There should be continuity (0&#937

That should tell us something to help narrow this down. Wish I had a free weekend and we could meet up somewhere in the middle and give this a quick couple of tests. Should be easy to resolve once we get all the information.

 

[Delivers1234]

Looks correct.



If you have a multi-meter or a continuity tester, there are a few tests you can run to rule out some common issues:



Disconnect the coax from the radio. Leave it connected at the antenna end, with the antenna installed.

Check for continuity at the radio end of the coax between the center pin and the outer shield. There should not be a connection between these two. If there is, stop and fix. (infinite ohms)



Check for continuity from the outer shield of the coax (at the radio end) to the vehicle chassis. There should be continuity if your antenna mount is correct. If there isn't, you need to fix this. (0Ω or a low number. A bit of resistance is OK)



Check for continuity from the center pin of the coax (at the radio end) to the vehicle chassis. There should not be continuity if everything is correct. If there is, stop and fix. (infinite ohms)



If you get through all that OK, your coax and connectors are probably OK. When doing the tests at the connector ends, try wiggling the coax cable around a bit where it enters the connector. This is often where the issue lies.



Last test for now, and you'll need some help with this:



Check for continuity from the center pin of the coax connector at the radio end to the antenna whip. There should be continuity (0&#937



That should tell us something to help narrow this down. Wish I had a free weekend and we could meet up somewhere in the middle and give this a quick couple of tests. Should be easy to resolve once we get all the information.

Thank you. I'll work on it.

 

[Delivers1234]

I got 0.017ish on outer coax to chassis. I used the 200k setting that had the little ground picture

 

[gewecke]

Are you 100% certain that your carrier is actually grounded to your vehicles frame? If you did a continuity check between your frame and the mount, your Vom should see it as a direct path. Again I think a roof mount antenna would be much more efficient than your 102" whip. Plus you wouldn't have to worry about that thing swatting the vehicle behind you? Imagine trying to go through the drive up with that... 73, n9zas

 

[mmckenna]

I got 0.017ish on outer coax to chassis. I used the 200k setting that had the little ground picture

OK. That's the diode symbol, so it's just checking for continuity at the 200Ω setting, it'll probably beep at some point.

17 ohms isn't bad, but I agree with gewecke, you do need a better connection. If you are just relying on the hitch receiver for the ground, you might need to do something a bit better. The metal to metal connection will vibrate as you drive and may cause issues. Using a ground connection to the chassis of the vehicle might improve things a bit, but I don't think it's your primary issue.

 

[Delivers1234]

OK. That's the diode symbol, so it's just checking for continuity at the 200Ω setting, it'll probably beep at some point.



17 ohms isn't bad, but I agree with gewecke, you do need a better connection. If you are just relying on the hitch receiver for the ground, you might need to do something a bit better. The metal to metal connection will vibrate as you drive and may cause issues. Using a ground connection to the chassis of the vehicle might improve things a bit, but I don't think it's your primary issue.

On the picture it shows a red wire, ground from the antanne mount to the chassis. My mechanic scratched out metal on the chassis then bolted it.

I'll try more work on Monday then if not go to ham radio outlet for help on sat. I also have a cobra 25 coming in next week. I did notice today while in Monterey and driving to salinas I heard the same person on 28.

Thank you all for being responsive to my request. It's neat to be in a hobby where everyone helps.

 

[mmckenna]

OK, if it is a direct connection to the frame of the vehicle, then you are good. My concern was that you were using the hitch as the ground connection.

Since direct current grounds, like your meter shows, is different from a radio/RF ground, I think you are probably OK there.

If you did all the other tests and they passed OK, then it really is likely going to come down to either the antenna itself or the SWR meter you are using.

Since there is a chance of rain here locally, you do need to make sure you seal up the coax connection at the antenna end. The connectors are not intended to be waterproof, and getting water inside there will damage the cable. Once the water gets in, it's impossible to remove.

 

[TheSpaceMann]

On the picture it shows a red wire, ground from the antanne mount to the chassis. My mechanic scratched out metal on the chassis then bolted it.

I'll try more work on Monday then if not go to ham radio outlet for help on sat. I also have a cobra 25 coming in next week. I did notice today while in Monterey and driving to salinas I heard the same person on 28.

Thank you all for being responsive to my request. It's neat to be in a hobby where everyone helps.

I believe a Cobra 25 is an AM only radio. You might want to get a SSB radio instead, so you could connect with the lower sideband crowd!