Building a crossband repeater - 2 transcievers or 4 units?

thebigphish · Post by **thebigphish** » Mon Jun 21, 2004 8:21 pm

I'm installing a new crossband repeater in our town (ty north madison!) and have a question about the units in it. This is ultra low budget, and will be run from our station house.

quick synopsis;
town operated LTR system
our dept VHF channel (duplex)
NHRC-7 repeater controller
Town system is on CDM1550LS+
Our system can be on any of the following CDM1550, m1225, A9 spectra or MCS2k Mod2 (i'm leaning towards the CDM1550)

now, the NHRC-7 will run two transcievers (one per port) or the ports can be split for TX / RX in separate units. If i set it up with TWO transcievers (one town & one ours) will there be any user determinable difference than if i set it up with dedicated TX / RX units (town RX into our TX and vice versa)? Will i have any noticable difference if i go with 2 units instead of 4?

thebigphish · Post by **thebigphish** » Thu Jun 24, 2004 7:17 pm

wow, is this that boring a post?

KB2ZTX · Post by **KB2ZTX** » Fri Jul 16, 2004 12:43 pm

OK.

So you want to talk from the LTR system to yours ? Correct ?

Just strap the 2 CDM radios to the controller and walk away. I have done this with a CDM1550LS+ (on our LTR trunking) and hooked it to a CDM750 UHF to give me a inband repeater. I have also done this with a lowband 750 with great results.

I'm not sure how the controller you have works, I use a RICK from motorola. On a couple of the units I use no controller, but add a toggle switch in the path. Check out the "cheap" way to link both those radios together - http://batlabs.com/rptrcabl.html

Radio1 Radio2
PIN 3 PTT ___________________ PIN 8 COR
PIN 8 COR ___________________ PIN 3 PTT
PIN 5 TX Audio ___________________ PIN 11 Disc Audio
PIN 11 Disc Audio ___________________ PIN 5 TX Audio
PIN 7 Gnd ___________________ PIN 7 Gnd

Make sure you program your pins in both CDM units.

Hope I helped....BTW I know all about those "jean pocket buget" systems.

Jeff

thebigphish · Post by **thebigphish** » Mon Jul 19, 2004 10:20 am

thanks jeff, that's what i had already done (with a copious amount artistic freedom)....my question was...would i be cutting down on the pre-time and lag if i split each port into a RX & TX pair of radios, rather than a single duplex unit....

i went with the controller because the system would ultimately would go from "bridge" to "repeating bridge", and the ghetto-wire plug job (the batlabs directwire special) that i've had in place for the last year has too many shortcomings...most notably the lack of port dependant IDs, acks and routing possibilites.

i've played with both sides of the road (the direct wire and the controller), now i'm just figuring out how to finalize the setup. 2 radios, 3 radios or 4.

n5tbu · Post by **n5tbu** » Fri Feb 04, 2005 8:42 am

One problem....if the LTR radio happens to get a denial,you have no way to know.
mod

thebigphish · Post by **thebigphish** » Sat Feb 05, 2005 8:44 pm

way to ressurect an old post!! and yes. that was considered, as well as noted as a problem in the inital design plans. thx.
btw. it's done.

SonicSounds · Post by **SonicSounds** » Sat Apr 23, 2005 4:34 pm

It's done? How did you do it and did it speed up what you were aiming to speed up?

Jon

Jay G. · Post by **Jay G.** » Mon May 02, 2005 8:10 am

Sorry to keep this one going!

I am using a cable setup exactly as you described to make a crossband setup, low band to UHF

HELP! How do I set up the accessory connector on both radios? phone patch? not working.....

UHF is 16ch GM300
Low band is Maxtrac or radius (I have 2)

Thanks for the help!

thebigphish · Post by **thebigphish** » Tue May 03, 2005 1:03 pm

SonicSounds wrote:It's done? How did you do it and did it speed up what you were aiming to speed up?

Jon

got fed up with the mobile to mobile set up (and hooked the MTR2000 VHF backplane up to the UHF simplex repeater we "aquired")

the mobile to mobile delay (namely the VHF ---> LTR (yes we knew it was gonna happen)) was horrendous...usually over 1.5 seconds before the LTR would come up...for some reason, the mobiles wouldn't get an ACK from the LTR controller and it would just busy signal us to death.. But the two repeaters going side by side are sick....no real delay.