On Aug 10, 10:43 am, "Radiosrfun" wrote:
"Martin" wrote in message
oups.com...
On Aug 9, 6:03 pm, **THE-RFI-EMI-GUY** wrote:
Martin; Are the 7400's capable of GMRS repeater operation? If so, where
did you buy them?
Martin wrote:
Hopefully someone who reads this group will be familiar with these
radios, Motorola T7400 FRS/GMRS. The alt.radio.family newsgroup has
degenerated to an unintellible level.
My friend and I have a set of these, which work extremely well as
general-purpose handhelds (much better range than our IC-Q7s, and only
cost $20 a pair after rebate). We'd like to use the T7400s for bike-
to-bike communications on motorcycle trips. Our plan is to mount
small speakers inside the helmets, and a microphone element in the
lower face guard, to reduce wind noise. There would be a PTT switch,
most likely mounted near one of the handgrips.
What we can't seem to find are the required tech specs on the speaker
and microphone elements, or a wiring diagram for the single plug that
connects everything to the radio. I'm aware that some radios short
the mic element with a resistor to actuate PTT, but need a lot more
specifics for this model.
thanks and regards,
Martin
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."
"Follow The Money" ;-P- Hide quoted text -
- Show quoted text -
Hi Joe,
As far as I know, the 7400 radios do not have any frequency-offset
capablity, but I suppose it's possible that there are undocumented
features. For example, if you engage the "QT" function from the menu,
it layers a tone squelch over the standard CTCSS (actually uses the
tone to precede the first transmission), which virtually guarantees
that no other extraneous sources will activate the receiver.
I bought them at Fry's Electronics in Dallas, TX. They were $20 per
pair, after a $10 rebate. The maker claims 8 miles optimum range, but
we tested them and got 10 miles. Here is a link to my review, which
also gives the locations and terrain details:http://groups.google.com/group/alt.r...thread/thread/...
These are the only blister-pack radios I have ever tested that beat
the manufacturer's range claims. And they did so using rechargeable
NiMH batteries, which have a slightly-lower terminal voltage than the
alkalines often used to generate the claims. Part of the performance
is no doubt due to physical reasons - the chassis is probably twice
the size of most FRS radios, and it uses four AA batteries instead of
the now-typical AAAs. I'd say these radios are far more likely than
most to actually deliver their rated output power. And perhaps they
have a good receiver section as well, plus enough chassis mass for the
antenna to work properly. For whatever reason, the peformance was
outstanding for something that retailed for $10 per unit.
best regards,
Martin
I bought a couple sets of FRS/GMRS radios and have yet to see them perform
to what "I" feel is their capacity. They claim upwards of 8 or so miles -
yet I lost contact with someone a hair short of a mile away on flat
terrain - and a virtual clear shot. At 3/4 mile, had crystal clear Comms -
but past that - nothing.
I don't place any faith in those things - as to range. I bought them to try
to stay off of "2 meters" with mundane things and to also use for Emergency
Comms with my assistants who aren't licensed and not "authorized" to be on a
Public Service band radio - I'll stick with the 2meters. I can do simplex or
repeat and not have to worry about losing contact - over the FRS radios.
That mile "and more" is very easily covered.
I never got around to it, but I'm going to check mine on my service
monitor - to see what they're doing - using AA Alkalines, NiMH and external
power source. I know many hunters who use FRS radios (only when hunting) -
of different brands, models, Rf power out and range quotes - and they always
complain of distance. They're not radio enthusiasts - of any sort. Listening
to their reports - quizzing them on their terrain and so on - I can
understand their issue. IMHO - I think those radios (at least most) are over
rated - a "gadget" item.
L.- Hide quoted text -
- Show quoted text -
For the most part, my experience with FRS radios has been the same as
yours - slightly more than toys. I tend to use 2M for short-range
communications with other Hams, but it's always handy to have some FRS
units on hand to toss to a non-licensed person in a caravan or
recreational group. Around here, the FRS band is mostly unused except
on Christmas morning and maybe for a week afterwards
The Motorola T7400s, though, shocked me with their real-world
performance. Especially considering their on-sale price of $20 per
PAIR. They met their range claims with margin. Of course, being in a
UHF band, they perform no better than you should expect with houses
and trees between rubber-duck antennas.
Martin