Mobile antenna issues

[Turbo T]

I have a Tram 1180 antenna hooked to my Yaesu FT7900. I was communicating with a 2 meter repeater just the other day that was roughly 5 miles from me. As I was listening, the repeater signal sounded like it was fading in and out, while I was driving 70 mph down the 4 lane highway.

I have talked to this same repeater before, in the same vehicle, same antenna and radio, sitting in my drive 10 miles from the repeater, and I could receive with no issues.

I have found it seems on other frequencies I have a similar issue. I have read this antenna is not the best but I didn't know at the time much on VHF/UHF antennas.

I'm wondering if i should upgrade to a different dual band antenna? or what else can i check for? All of the allen screws are tight, the coil base is tight on the mag mount base. The PL259 on the radio is tight.

Thanks in advance.

 

[mackmobile43]

Have you checked to see if water has infiltrated the base coil? never know

Also check for a corroded pin .

 

[W5LZ]

My first though would be what are the differences in terrain between your driveway and the highway where you were loosing that repeater. That alone can make a huge difference. And then, have you checked the SWR with that antenna lately?
After that, I'd start taking a really close look at the antenna, is it different in any way, anything changed with it? Is anyone else having problems with the repeater coverage? That's certainly a possibility too. Any other ideas? Color of your socks maybe?
- 'Doc

 

[Turbo T]

I didnt check to see if water has entered, but then again this antenna has spent most of it's life in a garage and has really never been exposed to rain.

As for the terrain....mmm....hard to say, there are some minor hills, but not what I'd consider were big enough to cause range issues. It's not what I'd call terribly different between my house and the repeater and where I tried keying up during travel.

 

[W5LZ]

I didn't say that 'terrain' thingy as well as I could have. It's what's between you and the repeater, not necessarily what's immediately around you. It's not easily determined in most cases, you just have to try it and see. And it doesn't have to be piled up dirt, as an obstruction to a signal, it can be man-made things too, buildings, etc. What's visible to you isn't the same as what's 'visible' to your radio.
That's the most common reason for what you're experiencing, but certainly not the only thing that can cause it. I just don't know enough about your area and what-all to make a good guess.
Good luck.
- 'Doc

 

[gamegetter]

maybe the repeater was having problems that day.

water or other wise.

 

[Moleculo]

Sometimes just whatever weird atmospheric conditions that are happening at the time can cause funny things.

Last week we got what are called the "Santa Ana" Winds. It's a strange weather condition that we get a few times a year that result in severe, erratic winds. When that happens, it is very dry, low humidity and it seems to result in a lot of static. As a result of these conditions, I couldn't hold a repeater with my handheld that's only about 10 miles away on a hill which I use almost every day. Just one of those deals that happens sometimes.

Before you start buying new antennas, verify the things already mentioned, and make sure it wasn't the repeater or some weird atmospheric conditions that were the culprit.

 

[Turbo T]

Understand about the conditions, just I figured a repeater that was less than 10 miles away would come thru loud and clear.

I'll do some checking. I have tried 2 other repeaters and found the same thing, that I fade in and out according to the other party...until I stop the vehicle.

 

[gamegetter]

one other consideration maybe flutter-the affect on reception due to the motion of the vehicle.

 

[Turbo T]

I was kinda thinking the same thing, but I didn't have this much trouble when I used to run 11 meters.

 

[milkman21218]

Turbo I seen the Tram 1180 coils melt when they get warm. So also check your SWR.