I am drinking from a fire hose with all of the information out there, being new to the hobby. Needless to say, I am confused.
What I am looking for is an antenna recommendation for an '05 Jeep Wrangler. The radio I ordered is the FT-2900r, and my preference is to use the Teraflex mount that goes behind the tail light. I ordered the radio as a package, so it came with a magnetic antenna, but I am now regretting the purchase. I plan on either cancelling that part of my order, or saving it for my truck when I get a radio for my truck.
Cancel the magnetic mount if you can. You can easily do better. Those are sold as a "quick and easy" way to get on the air. Certainly not as a real solution to having a good antenna installation.
I have absolutely no idea where to start with regard to an antenna that would work for my Jeep. While sounding picky, here area few questions/preferences I have, but I would't want to compromise the performance to much.
1 - I would prefer that it not be too long. It doesn't have to be short, but I would prefer that it not stick up above the roof by more than a couple of feet, both for aesthetic reasons, as well as not wanting to get it hung up on overhead branches and such while out hunting. Is this a reasonable request?
That is a reasonable request for VHF and UHF frequencies. Antenna length is tied to it's operating frequency. There are ways to "cheat" and make an antenna look shorter than it needs to be, but in this case you can do OK.
Keep in mind that prefacing your antenna installation question with the words "aesthetic" is going to take you in the wrong direction if you want a properly working system If your primary concern is that an antenna look good rather than work well, you can just slap any old antenna up and move on. On the other hand, if you want the radio to work well, you'll need to give up some of the aesthetics.
2 - I have heard the Teraflex mount needs modifications (the hole needs to be opened up) to be usable with an "NMO" mount. Is this a preferred type of mount? What other options are there that would better suit my needs?
This is a less than ideal location to mount the antenna, but it can be made to work if that is the only option you are willing to consider. Actually, mounting antennas on a Jeep and getting it to work well can be a challenge.
The type of base you chose will dictate the type of mount. NMO is certainly very popular and a good choice. A "standard" NMO mount requires a 3/4 inch hole, but you can get NMO mounts that will use a 3/8" hole.
3 - Ground plane - What do I do about this?
Ideally you want one, really. Unfortunately, you are going to have a hard time getting one unless you mount the antenna center of the roof or center of the hood. Neither sound like a good option for you. A ground plane is simply the "other half" of the antenna. Most (not all) antennas require a ground plane underneath them to get a proper match (low SWR) and for them to radiate the energy equally in all directions. Mounting your antenna on the rear of the body tub is going to make getting a good ground plane under the antenna nearly impossible.
This doesn't mean we can't make it work. Look at all the old military jeeps. They had their antennas mounted off the back corners, usually, and they worked.
You have a few options here:
1. go with a ground independent antenna. 1/2 wave length antennas do not require a ground plane to get a good match, but they do work much better with a good ground plane. You can mount a ground independent half wave antenna at the location you are considering and it'll work OK. The radiation pattern is going to be a bit lopsided, but that's the drawback of mounting in this location.
2. Use a non-ground plane independent antenna and just live with the results. It's not going to be perfect, but it's going to work. Don't expect great results, but I've seen amateur radio operators do worse things to antennas.
4 - As I've read, and shopped for the items, I noticed that antennas seem to be specific for a particular range of frequencies. Does that mean that if I am stuck in the woods, I won't be able to talk to a person who is, for example, in the 154.xxx frequency, if my antenna is setup for something closer to 144.xxx? Please explain my options here, is it length, material, etc.? Would I need multiple antennas, depending on who I am talking to?
Any other help would be great!!
Yes, antennas are frequency dependent. They are tuned for a specific frequency where they resonate properly. Tuning an antenna correctly will allow the most amount of RF energy to radiate effectively. An improperly tuned antenna will result in less RF energy being radiated. Un-radiated RF energy causes issues with the transmitter, and if operated this way for too long, can damage the radio.
The good news is that some antenna designs are a bit "wider" in their operating frequency than others. This means that they'll operate effectively over a wider frequency spread.
But, hold on a second....
Out of the box, the Yaesu FT-7900 will NOT transmit outside the amateur radio bands. 154.xxx is outside what the radio is designed to do. There are hacks that will make it work, but you'll have reduced performance. There are also legality issues here. Your amateur radio license does not give you permission to transmit outside the amateur radio bands under any circumstances. Using this radio outside the amateur radio bands will put your amateur radio license at risk, as well as the license of the system outside the amateur radio bands you are trying to operate on.
But, the decision is up to you....
If you want to use this radio on both the 2 meter amateur radio band and the 70 centimeter amateur radio band, you are going to want a dual band antenna. Finding a ground independent dual band antenna is going to narrow your choices a whole bunch.
While I'm not a fan of the amateur grade antennas, here is an option that will work for you:
https://www.dxengineering.com/parts/dmn-nr73bnmo/
As for the NMO mount that fits the 3/8" hole:
http://www.theantennafarm.com/catalog/pctel-ke794-7570.html under the "connector" drop down menu, select PL-259 installed. That will match the connector on the back of your radio.
Important thing on these NMO mounts of this style, they are intended for installation through a vehicle roof where the outside is outside and the bottom of the mount is inside where it's protected. Mounting this entirely outside the vehicle is going to expose the underside of the mount to water, dirt, mud, road salts, etc. You MUST seal them very well to protect them. Failing to do this will corrode out the underside and the coax resulting in damage that will require full replacement of the mount and cable.
As for grounding....
Even if you go with a ground independent antenna, like the one I linked to above, you should make sure you have a good ground connection on the base. Keep in mind the Direct Current ground, like used for hooking up vehicle accessories is a different beast than RF ground. You really need to have a good ground connection to the vehicle body. You also need to install an extra ground connection between the vehicle body and the tailgate. Failing to do this usually results in problems getting the antenna to match correctly.
As for the radio installation:
Power your radio directly off the battery. Do NOT tie into existing circuits in the vehicle, especially the lighter sockets. Your positive power lead should go to the positive post on the battery with a fuse installed within a few inches of the battery connection.
The negative lead should get grounded to the vehicle body where the battery negative lead is connected to the chassis/body. You also really should install a short ground strap from the radio body to the vehicle body. This will prevent a lot of issues down the road.
External speakers are also a really good idea, especially in a Jeep. The little speaker on the FT-7900 is pretty weak. In a jeep it's probably going to be useless. Get a good external speaker and mount it under the dash.
