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Old 02-09-2008, 06:04 PM
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DaveInDenver DaveInDenver is offline
Hard Core 4+
Join Date: Jun 2006
Location: Larimer County
Posts: 6,613

Originally Posted by Hants View Post
... and I'm a gadget freak.

I'm in the market for a mobile radio & HT. I'm pretty sure I want the following features:

2M & 70cm (is there significant utility to having additional mobile bands?)
50W (power is good, is more power better?)
Cross-band repeat (full duplex to/from HT)
APRS (I already have the GPS; does anyone here have first hand experience?)

I curious about the following features/technologies:


Has anyone here used them? How widespread are repeaters that support them, particularly in the backcountry? Internet anywhere would be the goal.
That's a pretty long list.

First Echolink and D-STAR. D-STAR is thus far only on ICOM radios and not particularly wide spread. Echolink, not familiar with it other than having heard of it. IOW, never used it. This could be handy if you want to talk to someone at home, since it's a way to talk to someone on a computer. But the person on the computer has to be a licensed ham I think, since their voice will be coming over a radio. Although that might fall into the auto patch provision, where it's legal to have a non-licensed person on the phone. I dunno, not familiar with it too much and couldn't tell you the number of repeaters around that might have access to it.

Cross band repeat will lock you into a few radios. Yeasu 8800 and 8900, Alinco DR-635T or Kenwood TM-V71A. All of those can accept a TNC for packet radio, but none have it built-in. For APRS the best radio is the Kenwood TM-D710A, which is dual band but not cross band repeatable. the D710A has APRS functions built in and those make it the most friendly. But any radio with a TNC capable port will be adaptable to packet radio. For that the best TNC option is a Kantronics MT1200G, which has a port for a GPS receiver and so you don't need the PC if all you are doing is APRS. If you want to do packets, then you need the terminal, which is most often a laptop. Some people have rigged up dumb terminals with a keypad and LCD display, but there's nothing commercial for that really.

Power wise, most every dual band does 50W on VHF. Most are less on UHF, in the 35W range. Don't worry about that too much, the difference between 35W and 50W is not huge. Range goes approximately by the square root of the power increase. So the difference in approximate range from 5W to 50W is SQRT(50/5) = SQRT(10) = 3.2 times the range. So the difference between 50W and 35W is SQRT (50/35) = SQRT (1.43) = 1.2 times, so just 20%. Also remember you will spend most of your time at 5W or 10W, since that's about all you need to get into the repeaters around town. Having 50W for simplex is good, but you shouldn't be concerned with more than about 50W or 60W. Also remember as you increase power, you increase your RF exposure and so you want to be careful about antenna placement with higher and higher powers, even at 50W you need to make sure to keep about 6 feet or so between you and the antenna when transmitting to stay below accepted FCC exposure levels.

Bands. Sure, more bands the better. But only if you have someone to talk to. Probably 75% of the time you will be on 2m (and primarily all the time in the club, some people have single band 2m radios). UHF is handy for caravans, but only if everyone has the band. Having 6m can be OK to mess around with, but not heavily used. Then 10m, well mobile radios only do 10m FM and that's not all that common, either. There are some 10m repeaters, so that could be OK. Mostly 2m and 70cm will get you 99% of the stuff we do as 4WD'ers, the rest depends on how much you want to tinker with it as a hobby.
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