XTL2500 Problems and more!!

[mmckenna]

What kind of SWR meter are you using?

You should be able to adjust the antenna to get the SWR lower. Since quarter wave antennas are broad banded, it's pretty easy to bring it down. The ideal point for these antennas is pretty wide.

What you'll need to do, though, is figure out if you need to make the antenna longer or shorter. Without an antenna analyzer, you'll have to loosen the set screws on the antenna and adjust it as long as it will go. Check SWR and see if it went down or up. Do the same with inserting the whip as far as it'll go, check SWR again. It'll improve one way or the other. That'll tell you if it needs to be longer or shorter. If it needs to be longer, you will need to order a longer whip. If it needs to be shorter, you'll have to trim off 1/8" at a time until you get the SWR down.

1.86 isn't bad, usually radio manufacturers will tell you to keep it under 2.0:1. But, you really want it lower. The lower it is the more RF energy gets radiated by the antenna.

And, I wouldn't replace that antenna. That one is a good choice for what you are doing. I couldn't recommend something better.
Quarter wave antennas are ideal for this sort of use. They are short enough to not hit the top of the apparatus bay door, and they have a wide bandwidth that makes them well suited for interoperability uses where you have a lot of widely spaced frequencies to use.

 

[emtunderwood]

I have a Bird Meter. Also, the antenna we have isn't adjustable the whip runs straight through the cap and is terminated to where it hits the center pin of the mount. So a better antenna may be another part of the solution.

 

[mmckenna]

Ah, got it. I went back and looked at the model number you listed, I was wrong.

Larsen NMOQC is what I like to use.
Larsen NMOQSPEC is a cheaper alternative.

Others I've used with good results:
Larsen NMOWBQC heavier whip, not as flexible, but has a spring base.

 

[emtunderwood]

Ok cool deal. I'll get one of those.

However, Pierce Technician came out this morning and went through the truck and ran a complete system diagnostic and found that the link between the Load Manager and Voltage Regulator was bad. But looking at the line between the two all connections and continuity are great. Put a jumper bypassing the alternator to the load manager found the Voltage Regulator to giving readings all over the chart but nothing over 11v.. Problem Found!!!! line straight from the regulator runs directly to the fuse box where the radios are supposed to be wired. Bypassed that directly from alternator to the fuse box and bam, truck running, all lights on and even stomped the Q and no humm, wine, or oscillation on the system. Also, standing wave down to 1.1-1.2:1. I think that solved the problem. Replacement voltage regulator will be in tomorrow. I hope this is the final solution to all the problems.

 

[mmckenna]

Good deal. Glad to hear it's fixed.

 

[ME801]

thanks for letting everyone know what the solution was. Often we work on a problem, but never hear what the solution was.