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So I think I'm ready to pull the trigger on a TM-281a (like pictured above).
My plan is to set up in the toy hauler with a small base station antenna setup for spectating and pit duty.
http://www.hamradio.com/detail.cfm?pid=H0-011362
Seems like a good price to me.
So, my questions are:
Will I be able to program in whatever freqs I will need?
It will work with any 2m antenna, correct? Since the RV has a rubber roof, I assume I'll need a small-ish antenna with built in ground planes? Can I just mount the antenna on top of my flag pole that isn't grounded?

Ok, guess I've been living in a cave or something... but doesn't anyone use CB radio's anymore?

Big Dave wrote:So I think I'm ready to pull the trigger on a TM-281a (like pictured above).
My plan is to set up in the toy hauler with a small base station antenna setup for spectating and pit duty.
http://www.hamradio.com/detail.cfm?pid=H0-011362
Seems like a good price to me.
So, my questions are:
Will I be able to program in whatever freqs I will need?
It will work with any 2m antenna, correct? Since the RV has a rubber roof, I assume I'll need a small-ish antenna with built in ground planes? Can I just mount the antenna on top of my flag pole that isn't grounded?

That is the one I have for the race car, Dave. (from the same place, too) After the mars/cap mod (easy) you can program in everything and can even program the radio without the fancy microphone. I will be getting another for a base station, too. You can also program it, then put it into a "commerical radio" type mode where it just goes to the channels you have set and gets rid of the fancy tuning and scanning options that are sometimes confusiing. And you can set a prioroty channel for whomever you are pitting for, then still scan the rest of the frequencies to keep up on the action.

You can buy antennas that don't need a ground plane, but I don't know much about that. Any 2 meter antenna will work, but ideally you want something that covers the "business band" and you can trim it to the center of your target frequencies.

craigvwdude wrote:Ok, guess I've been living in a cave or something... but doesn't anyone use CB radio's anymore?

Used in a legal configuration... very limited line of sight range, max power 5W.

Good for short range chatter only, still have their place.

edit--> Another thing I like about the 281a is it just takes an ethernet cable from radio to radio and you can clone radios so they are exactly the same programming. Like for my race and chase radios.

Hey Dave, I had some time to kill tonight, so I did some looking.

I found two antennas that have good reviews and should suit both of our purposes... x50a and gp-3, both around $100... but they are for the ham bands.

https://www.theantennafarm.com/catalog/ ... yword=x50a

https://www.theantennafarm.com/catalog/ ... yword=gp-3

If you search for "MURS" antennas, they are tuned for the business band... Just be sure that it can handle the extra wattage.

I hear good things about "j-pole" antennas on the ham sites. The good thing here is you could build one yourself pretty easy, and it's super durable.

This site is how to build one and tune it, it has a picture at the bottom with dimensions and a calculator to get the specific dimensions for your frequency. I targeted Weatherman frequency when I tuned my antenna because it's about in the middle and I figure that would be the "distress" channel when you would want maximum range.
http://www.buxcomm.com/jpoles4ever.htm

This looks like a good premade one for $39. Says "no ground plane" and "covers 150-160mhz"
http://www.arrowantennas.com/osj/j-pole.html

Other notes that I took in from reading... at least 6 feet from metal objects to the side... get good low-loss rf cable...

I rally like that J-pole antenna. Cheap, rugged and pretty small. I am thinking I could mount it to the top of my ladder and just loosen the U bolts that hold it, rotate the whole thing to lie flat and tighten it back up and just let it ride stowed away on the roof until its needed again.

Great research, guys. I'm working on acquiring a new "base/tow/shop vehicle" which I hope to have at the May Wendover race. This will help in getting that set up.

I found this "Master List" at RD. I'm unsure how recent it is, but it seems pretty up to date.

https://www.google.com/url?q=http://www ... SsWcYoKO2w


Anybody know what freq(s) I will need for BITD at the Mint?

Nice list, Dave.

In regards to j-pole...

The J-pole design functions well when fed with a balanced feed (via balun, transformer or choke) and no electrical connection exists between its conductors and surrounding supports.[3][4] A common approach extends the conductor below the bottom of the J-pole resulting in additional and undesirable RF currents flowing over every part of the mounting structure.[3] This modifies the far field antenna pattern typically, but not always, raising the primary lobes above the horizon reducing antenna effectiveness for terrestrial service.[4] J-pole antennas with electrical connection to their supports often fare no better, and often much worse, than the simpler Monopole antenna.]

Looking at pci, they offer a more traditional fiberglass encased antenna, but it's $150 or so.

Big Dave wrote:Anybody know what freq(s) I will need for BITD at the Mint?

BITD uses 151.190. Weatherman 151.625 would be good to have too. There may be others as well.

Here is how I set the radio up - frequency wise

CH1 WEATHERMAN (151.625)
CH2 BFG RELAY/SNORE/MORE (151.715)
CH3 BAJA PITS (154.980)
CH4 NETWORK (151.685)
CH5 CHECKERS (151.925)
CH6 FAIR (150.860)
CH7 MATOMI RACE (XXX.XXX)
CH8 LOS CAMPEONES (152.960)
CH9 CHECKERS VEGAS (151.505)
CH10 BFG PITS (153.395)
CH11 MAG7 (153.380)
CH12 RESCUE (155.160)
CH13 CORE (153.245)
CH14 LOCOS MOCOS (151.775)
CH15 BITD (151.490)
CH16 PCI RELAY (154.515)

To manually input frequency:

On Radio - PRESS VFO SOFTKEY
On Mic - PRESS PF(D) ON KEYPAD
On Radio - USE DIAL TO TUNE IN FIRST THREE NUMBERS
On Mic - USE KEYPAD FOR REMAINING NUMBERS
On Radio - ONCE COMPLETED, PRESSING MR RETURNS TO MEMORY

I have it set to scan memory bank, if needed, I can manually add in a secondary channel or other frequency for help

To scan memory channels:

On Radio - PRESS MR SOFTKEY AND 1 ON KEYPAD FOR ONE SECOND
PRESSING MR SOFTKEY AGAIN WILL STOP SCAN

It's been a while since I have played with it but think the above is fairly accurate

Also....

This was the antenna recommended with a MFJ-921 tuner

https://www.theantennafarm.com/catalog/ ... =tram+1487

Dave and my radios both worked excellently at the Mint. We were both easily able to transmit and receive with any other spot on the course. I was jealous of his ability to program on the fly, though, through the front panel. I had my laptop, but not the right cable or software to reprogram when BITD decided to change freq's during the time trials due to interference. Luckily, they fixed the problem and switched back for the race.

I also picked up to handheld scanners for Jarad and myself to monitor chatter when we were away from the vehicles.

http://www.uniden.com/scanners/bc75xlt- ... t/bc75xltg

These little numbers worked fantastically. They are extremely easy to program from a laptop with a common USB to mini USB cable and free software, can be programmed on the fly through the front panel, and received nearly as well as our base units, even when in scan mode. Troublesome freq's or entire banks are easy to eliminate from the scan. We had the base units set to pick up BITD on one and Weatherman on the other, and the two scanners we were flipping around on, stopping on a certain channel when something useful, entertaining, or otherwise deemed listenable came up. Battery life was decent. We used NiMh rechargeables, which lasted about 8 hours if you were playing around with it a bunch (me), or about 12 if you were just listening at relatively low volume (Jarad). I anticipated this and brought an extra set for each unit, plus our solar charger and of course, the truck's cigarette lighter. As an added bonus, CB and UHF frequencies can be monitored as well, one I can use at the Salt Flats or for highway traveling entertainment, the other for work to monitor our telemetry and interference. It also picks up most of the local emergency freq's.

Operation takes a little getting used to as the controls are not completely intuitive, but I brought the manual, and by midday was able to navigate and make programming changes on the fly with no problem. When scanning, it would sometimes take a while to pick up a transmission, even when all other freq's were quiet, but scanning through 40+ channels took about a second, so it'd pick up sooner or later.

All in all, I would highly recommend this unit for spectating or as a mobile monitor as we used it.

Nice report. What kind of mobile antennas did you each end up with? Were you on a high spot or low spot or flat spot? How far were you communicating (Rx) estimated?

Thanks.

I guess I never posted back with the radio setup I bought.
I bought the Kenwood 281a, 50 feet of good coax, and the Tram 1487 base station antenna. Also bought a 25' extendable flagpole to mount the antenna on. I then hooked the speaker output into our trailer's external speakers, and the radio was more than loud enough to hear 100 feet away
I also bought an nice Larsen magnet mount antenna to use with the same radio. That worked well for the time trials where we just had the baja. The speaker on the 281a is actually quite a bit better than I was expecting.
We were on the back side of the mountain from the start/finish line, which actually put us about right in the middle of the course as the crow flies.

We were heard pound and clear all over the course from my radio, but since we were on the power line road, we were parked directly under the high tension lines that run over to the Hoover Dam. I don't know if that helped us transmit better, but I would like to try it some other time without power lines around.

BITD loaned out some mobile radios, and a few of those were transmitting pretty poorly....like the people about 1/4 mile away from us had one. We could hear and talk to them, but they could not talk to officials on the other side of the mountain. We had to relay for them a few times.