Batboard

I've tried various searches but cannot find the info I need so I'm throwing this out to the forum members for help.

I've got a buddy that just picked up three Saber 1 radios programmed for the MURS freqs that he wants to use in conjunction with ballooning. The chase vehicles need to keep in contact with each other and the balloon and radios are quicker than cell phones. I'm not sure what radio he's using now other than he's not pleased with the performance (it might be a Maxtor). He's using a BNC connector off the radio to a rooftop antenna with a magnetic mount. They don't balloon enough to warrant a permanent antenna.

Here's my question: going from the antenna connection on the Saber inside the vehicle to the rooftop; what do you recommend for connectors, cable, and antenna?

Thanks for the help; he will appreciate it a lot. Heck, for the right deal you might get a balloon ride out of. He didn't say so(and I can't talk for him) but he's a pretty decent guy and he likes introducing folks to ballooning. Geographically, he's about an hour west of Chicago.

Connecting an external antenna to a Saber I radio is a challenge. Unless you have the ability to build a special cable then the next best thing is to use a Saber Vehicle Adapter, known as an SVA. The SVA will provide you with the traditional antenna output connector that you need. Problem with the radio itself is that its antenna connector is single pole, meaning that in and of itself it has no ground connection for the coax cable. The correct, two-pole, connection is available at the back of the radio but you have to use the special multipin connector. The SVA will connect automatically when it is used, plus it will enable you to use a PTT speaker microphone. The number for the SVA is 5487 and they've become reasonable in cost over the past few years. The SVA, like the Saber, is no longer manufactured by Motorola but they're easily available. Search this Board, as well as the whole web, for
SVA, or 5487, etc. etc. and you'll come up with a ton of information. And don't use an AVA because an AVA is for a different radio.

I don't know if they're still available but for mine I have a Saber RF test cable, it attaches to the accessory connector, has about 2' of coax and a BNC on the other end.

01-80358A63

+1 for the Saber Vehicular Adapter suggestion. The full part number for the cradle unit is NTN5487 and they are all over eBay for very reasonable prices. Make sure if you get one that it comes with or you get separately the amplified speaker that goes with it, whose part number is NSN6054. The power plug can be salvaged from any old PC power supply and any Maxtrac/Radius mobile microphone will work with them.

Thanks for all the comments and insight. I had heard of the convertacoms, but didn't know how it expensive it was to not use an SVA and hook to just the antenna. It is clearly cost prohibitive and the SVA sure seems like a no-brainer and a nice setup.

If I can pick him up one of the SVAs, what antenna would you recommend I use for the MURS freq range?

You might wish to review the FCC's regs on the MURS channels, which are at:

http://wireless.fcc.gov/services/index. ... =multi_use

There is a note there that prohibits MURS operations by aircraft in flight, but I don't know if this would apply
to a balloon flight. You should probably check on this with FAA if your pilot is licensed and the balloon carries
a registration number.

Your Sabers would have to operate on channels 4 and 5 because they are not capable of narrowband operation.
Also, there is an output power limit of 2 watts in MURS, and Sabers can be set to go as high as 6 or 7 watts, so you would
also have to have the power output set to 2 watts when the programming is done.

With regard to antennas, I would opt for mag mounts on the chase cars with quarter-wave vertical antennas. If you
wanted to go a 3db gain vertical the antenna would have to be about three feet high instead of the quarter-wave's
18 inches or so and in your application you probably don't need that 3db of gain since you would be working mostly back
and forth to the balloon. The quarter-wave will cost about a quarter of the cost of the gain antenna, too.

Regards,

Gain and antenna pattern are opposite objectives in this case... the balloon may be over 45-degrees vertical from the mobile at times. 1/4 wave is best.