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Don't shoot..... I did check the search, but it gives conflicting opinions. I know to talk to Sampson, SpeedCom, RE, Zander, Sync Speed etc. What I need to find out first is it UHF or VHF that works the best for road race circuits? You know if you want to say hey to the guy at T7 in Atlanta. Or get a message to the crew from the back of TWS.
Next question, does anybody know of a radio seller that will take good quality trade ins?
Real experiance at TWS working the corner one the back side of TWS, the low one you get to first, with both SCCA on VHF and NASA on UHF. SCCA's VHF works much better.
On the courses back east/up north where you have a lot of thick vegitation VHF will work a little better.
UHF, smaller antennas and more channels available.
Given radios of similar power output and quality on 95% of the tracks you won't notice the difference.
Another option where you won't have to worry about liscensing, Cell phones with unlimited weekend minutes if the track has good coverage.
Pardon my ignorance of radios, but my Sampson-acquired Tekk NT-50 radios work fine from the pits to the backside of Road Atlanta (T7), from the pits to the backside of VIR (Oak Tree), from the pits to the backside of Summit (Carousel), and from the pits ot the backside of The Glen (the toe of The Boot). Tracks like LRP and NHIS are of no consequence.
Look up the technology of that radio and it could be useful info. - GA
My Vertex VX500 5 watt UHF radios work fine from the toe of the boot at WGI to pit lane.
VHF will go further with line-of-sight access. UHF will go further if there are hills/buildings/etc in between the two radios. This is why marine folks prefer VHF.
-Kyle
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VHF will go further with line-of-sight access. UHF will go further if there are hills/buildings/etc in between the two radios. This is why marine folks prefer VHF.
-Kyle
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Umm, this statement is not actually correct. UHF is a higher frequency than VHF, and the higher the frequency the less ability to follow contours of the Earth due to diffraction. Marine applications tend to use VHF first of all because spectrum is allocated to them by the FCC for that purpose, and also because VHF has slightly more ability to receive "over the horizon".
In any case, the radiated power level (and how good the receiver design for that brand of radio is) and frequency-dependent multipath interference is probably more of a deciding factor in whether or not a given radio works well at a certain track. So, if Greg or some other credible person says his radio works well all over WGI and VIR, and those are the "big" tracks you are going to, then that's probably all the info you need.
And yes, I stayed at a Holiday Inn Express just a few years ago :D
Another choice would be Ralph Warren ([email protected]) I bought a pair of excellent 15ch Motorola radios from him last year, three batterys, charger, and car plug in for little money. I did, however, have to furnish my own car harness so ended up spending what a starter system would cost from another source....BUT, I have commercial grade Motorola radios. Have used them at RR, RA, and Barber without an external antenna with no issues. Hope this helps, Chuck
I have a set of Vertex 5 watt UHF radios which I use at Road Atlanta. They are great on the front half of the track, but I loose contact on the back half. Even that limited contact beats a sign the heck out of a pit board.
Had I known about the lack of coverage I would have paid the extra money and gone VHF. (Bought the complete setup for $400.) Crew headset and radio, car radio, antenna, car harness, helmet mike and head set, and PTT switch.
Chuck
the radio is only half the "how far can i talk" equation. the other half is the antenna. you can have the bestest baddest radio in the world and if you have a rubber ducky antenna in your car or a poorly grounded roof mount it will suck. same for crew. that antenna on the radio on your belt is not anywhere near as good as one on a pole or even the remote mount antennas on the headset. the system is only as good as the least capable component.
marshall
i run a holiday inn..also known as the u.s. coast guard telecommunications command... :P
I purchased 3 Motorola Radius GP300 8 channel UHF radios in 2005. For $200, I got the 3 radios, 3 chargers, and 6 batteries. eBay!
That said, I was lucky that the frequencies happened to work out and I didn't have to go pay someone to change them. I bought a car harness, a crew headset, and a couple helmet setups from Sampson. They provided excellent telephone sales support and quality components.
For the price of a 2 radio starter set (with low-end radios), I got a complete 3 radio set with top quality radios.
These 5 watt radios have 100% coverage on Pacific Raceways, which has some elevation change and some areas that are definitely not "line of sight" from the paddock area. So far, I have not felt the need to put an external antenna on the car.
As a lifetime ham radio operator and someone who has worked in the land mobile radio service, I have seen a lot of radios, good and bad. I suggest buying the highest quality radios you can find, and I would put Motorola at the top of the list. There is a reason why they have been the first choice of professionals for decades.
A few weeks ago at the 8 Hours of the Cascades endurance race in Portland, OR, one of my Motorolas was dropped from the top of our team truck (about 15 feet) onto the pavement. The case has a small dent in a corner, but the radio is working fine.
If you can't find reasonably priced Motorola radios, the Icom and Vertex radios are also good quality, and I would buy them in that order of preference, based on my experiences over the years. Any other brands are questionable in my opinion.
As for VHF vs. UHF - it typically won't matter much for racing applications. With 2+ watts and an external antenna, you should have adequate coverage on virtually any racetrack. I prefer UHF because of the smaller antenna size for comparable performance.
I agree with Marshall that the antenna is key. The antenna is the first place to make improvements if your range is not adequate. Putting a 1/4 wave whip on the roof will make a HUGE difference in coverage compared to using a "rubber ducky" flexible whip on the radio mounted in the car.
If your mounting point for the external antenna is not on a metal surface, that won't work either without special considerations. You either need to find a metal panel to mount the antenna on, or get some metal foil tape to put under the mounting area (like inside the roof or trunk lid). Use at least 4 strips of the metal tape, at least 1/4 wavelength long (as long as the antenna), and make sure you connect the metal tape to the shield of the feed line at the antenna base. Orient the tape in an "X" with the antenna mounted in the center. Keep the feed line as short as possible, and cut to length rather than coiling up excess, especially with UHF.
If the external antenna on the car still doesn't give you the coverage you need, consider a small "base station" antenna. You can mount it on a 10 foot TV mast you can get a Radio Shack for a few bucks. Or use a piece of conduit. Anything to get it up a few feet in the air. Stick it in one of the stake holes in your truck bed and get it up in the air. Of course, the feed line will limit your pit radio physically, but may solve the problem.
I am interested to hear about experiences with different brands of radios that are being used.
Regards,
Mike
One question about the external antenna thing...what exactly is a 1/4 whip antenna. I have one that came with my setup but am having a hard time mounting where it looks good. I am considering trying a different antenna that mounts easier but what are the differences between a 1/4 whip for UHF and say one of those fancy new radio antenna's you see on new cars that are roof mounted. The ones in these newer cars are grounded to the metal roof and also use what looks like RG58 coax as well...is there any reason it couldn't be used with UHF radios as well or does it have to do with a certain frequency range? Sorry for the unedumacated question.
The electrical length of the antenna is very important to its performance. A 1/4 wave antenna is simply an antenna that is 1/4 of the wavelength of the frequency you will use it on. For UHF, which is about 450 MHz, 1/4 wave is about 6 inches long.
You can make an antenna that is much shorter than 6 inches look "electrically" like 6 inches, but there will be some reduction of performance. This reduction may not be significant if you properly mount the antenna on a metal surface.
Here is a simple formula for 1/4 wave antenna length:
234 divided by the Operating Frequency (in MHz) = length in feet
234/450=0.52 feet or 6.24 inches
I am not sure what type of antenna you are refering to CRXsi, but if you buy an antenna designed to be used at 450 MHz, and mount it as directed, it will most likely work fine for you.
Thanks for the advice Mike,
I am starting to understand this a little better now. If I am understanding this semi correctly I am running 462.xxxMHz meaning that I need a 6" antenna...now is there any harm to running a longer than 6" antenna (like between 6-7"). I am assuming that any length over the 6" is a bonus but am curious. Or is it better to just ensure the antenna used is designed for use in my range (450-470MHz)
Basically, when you're looking to buy the new antenna, you just want to make sure that the manufacturer specs it for UHF, probably something like 450-470 MHz for the 46x.xxx band you're using. Install it per the manufacturer's instructions, grounding it as well as you can. A metal mount antenna will probably have a good ground, especially if you clean a bit of the paint off the metal where the antenna mount goes through the car skin. Those little "juice can" antennae you see on Miatae replacing the stock antenna are most likely 450-470 MHz antennae. If you call someone like Samson or RE, just tell them you need an antenna for 450-470 MHz and the non-radio specs, like you want a "small can" instead of "long whip" antenna.
My car has a plastic roof where the antenna mounts. Currently having com difficulty at RA on the back side of the track. Would a 6" diameter circular piect of aluminum make a sufficient ground plane? Using Vertex VX500 UHF radio, and 6" whip.
Chuck
Try the 6" diameter piece of aluminum first. If that doesn't help (enough) then run a wire from that aluminum to a good chassis ground in the car. That should fix it right up.
I've been a radiohead since 1958, a radio EE since 1968, and a Ham since 1971 so let me see if I answer a few things.
- Marine radio is VHF because that's what the FCC assigned and VHF was available commercially before UHF. Technical reasons in that case are more subtle.
- from a pure propagation POV, VHF and UHF each have pro and cons in our racing environment but the path loss of UHF is greater
- ignition noise etc. is likely to be less severe at UHF
- antenna gain is easier to acheive at UHF and that gain can make up for loss etc
- feedline is lossier at UHF
- don't overlook elevating the base station end of things, even getting a small "real antenna"
- the 234/MHz formula does not include strays and can make things "long", checking VSWR is important (locate a local ham to help you)
- you can make a ground-plane inside your non-metallic roof using 3M #1311 aluminum tape
Somewhere in my basement, I have an old 'Ray Jefferson' marine radio from the OLD DAYS of two-way radio...with tubes and a dynomotor for the power supply. Weights ~100lbs., 5 'channels', all crystal controlled, in the HF band...as I remember, 2182 khz was the marine 'emergency' frequency. Definitely some propagation advantages at HF frequencies....when conditions were right, you could talk to the southern hemisphere. So much for the history of marine radio before VHF...Quote:
Marine radio is VHF because that's what the FCC assigned and VHF was available commercially before UHF. Technical reasons in that case are more subtle.[/b]
Jim plays in a pretty cool radio development world...spook radios, military stuff, etc. My only claim to fame is that I manage two different half-megawatt RF flame-throwers, on a hill about a mile from Jim's lab...one VHF, one UHF...and they can receive us there on their electric toothbrushes and coffe-makers. We're the 'noisy neighbors'.
Grounds....grounding makes a huge difference when dealing with antennas. And length matters, too.
That was an a old AM radio, which we often call Ancient Modulation now. Before my employeer went max-zoot we put the first HF-SSB marine on the market in 1961.Quote:
Somewhere in my basement, I have an old 'Ray Jefferson' marine radio from the OLD DAYS of two-way radio...with tubes and a dynomotor for the power supply. Weights ~100lbs., 5 'channels', all crystal controlled, in the HF band...as I remember, 2182 khz was the marine 'emergency' frequency. [/b]
Anyway, I'd be happy to answer radio questions... but don't overlook the use of cellphones. The Verizon "In" plan is an attractive way to do it cheap.
Yeah, the phone company puts up the repeater network. :-) I figure it would take be about a kilo buck to put together a portable UHF or VHF or UHF/VHF crossover repeater that I could drop on the ground, chain to a tree, and stab a 'tenna stake in the ground, and be on the air. From what I've heard, if you want to talk from the pits all the way around Road Atlanta, you pretty much have to have a repeater on the hill. Haven't tested it myself, tho.Quote:
Anyway, I'd be happy to answer radio questions... but don't overlook the use of cellphones. The Verizon "In" plan is an attractive way to do it cheap.
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has anyone out there used a CB radio in the car, with handheld cb's for the crew?
I've seen a CB in a BMW 2002 in the Northeast that runs in the vintage group. John Walsh also showed me his CB setup in his Miata.
What do others think about using a CB radio, either with the handheld mic and external speakers near the driver's head, or splicing into the mic wires and wiring for a helmet?
LOL... that's what she said... :lol:Quote:
...And length matters, too.
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Constructive input - yes, last I checked Rief is using a CB setup, pretty happy with that. I've been using a real cheap FRS setup for years, but I also have the equiv. of a short-track to work on - always line-of-site.
We do that because we're cheap, the interface connection is universal (think "air") and it works. With a variety of drivers in/out of the car for looong enduros, trying to make sure that everyone's helmet rig & connectors are correct and WORKING is a monsterous PITA. We just avoid the whole issue. It's been working great for the last decade of running enduros, and for us there is no point in fixing something that isn't broke. Besides, you get to talk to truckers at 3am when you're bored on the back straight.Quote:
has anyone out there used a CB radio in the car, with handheld cb's for the crew?
I've seen a CB in a BMW 2002 in the Northeast that runs in the vintage group. John Walsh also showed me his CB setup in his Miata.
What do others think about using a CB radio, either with the handheld mic and external speakers near the driver's head, or splicing into the mic wires and wiring for a helmet?
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Use a large whip antenna in the pits, ground plane is our Pit Lane canopy. Coverage is 'whole track' at most places we run...but we do fight ignition noise at Oak Tree at VIR or down in the Boot at WGI. Nelson ? Ha ! we could use smoke signals or an Aldis lamp.
We're probably going to go to 'helmet speakers' for the 24 hour, since the Piņata is a whole lot noisier than the old Showroom Stock cars...but you can do that for about $20/helmet if you use the stuff that the bikers on the Hondabagos use.
Have several sets of VHF/UHF HT radios for the other cars...they work OK, but we like the ubiquity, utility & price of the CB stuff...mostly cuz we're cheap bastards....