R. I. C. K. Issue

bundy125 · Post by **bundy125** » Thu Dec 28, 2006 10:29 pm

Hello All,

I'm trying to help a local Vol. Fire Dept. with an issue they have with a R. I. C. K. that they're using for a cross-band repeater. They're going from low-band to UHF using a CM300 and radius mobile, which keys up a repeater on the UHF frequency.

The problem: When they try contacting dispatch from the low band radios, their initial communications are clear, but when dispatch has completed their transmission, the low band units have to wait until the repeater unkeys to respond, otherwise, their transmissions are overridden by the repeater.

My Question: Is this a normal occurrence with a RICK or possibly a programming problem?

I have one of Will's extenders doing basically the same thing from VHF Hi to UHF and I have no problem of this sorts.

Any suggestions or input would be appreciated as this department doesn't have the funds available to go 100% to UHF.

Thanks in advance,

Bundy125

HLA · Post by **HLA** » Thu Dec 28, 2006 10:58 pm

cut down the hang time and that should fix your problem

bundy125 · Post by **bundy125** » Thu Dec 28, 2006 11:17 pm

Thanks for the rply HLA.

Just for clarification are you talking about cutting the hangtime on the repeater or the RICK? I can do that to the repeater, but I'm not that familiar with the RICK. I've read something about using the DIP switches to do that, but don't have any experience with it.

Thanks again,

bundy125

HLA · Post by **HLA** » Fri Dec 29, 2006 9:51 am

it's been a while since i set a rick up but if you run a search for the owners manual for it you can set the dip switches to zero hang time so as soon as one side dekeys the repeater also stops transmitting so the other side can reply quicker.

bundy125 · Post by **bundy125** » Fri Dec 29, 2006 12:42 pm

Thanks HLA,

I'll see if they can't dig up the owners manual and give resetting the switches a try.

Bundy125

bundy125 · Post by **bundy125** » Tue Jan 02, 2007 2:48 pm

Update on this problem.

The hang time on the RICK evidentially was set at zero on installation. It appears that the repeater hang time is overriding the transmissions when they are trying to talk back to dispatch. Is there any solution short of adjusting the repeater hang time as it is about right for the UHF side of the system?

Thanks in advance,

Bundy125

HLA · Post by **HLA** » Tue Jan 02, 2007 4:46 pm

so you're saying you have one repeater talking to another correct? and i'm guessing one side is disbatch? is disbatch transmitting with the repeater or is it at a remote site? if it's at a remote site you could try and change the frequencies around a bit. instead of the input to the crossband getting it's signal from the output of the main repeater, change the input frequency on the crossband to recieve the same as the input of the main repeater and that will cut out the crossband from hearing anything from the main repeater. if that made sense? but that won't work if disbatch is transmitting from the main repeater. other than that i'm out of ideas.

bundy125 · Post by **bundy125** » Tue Jan 02, 2007 5:15 pm

Hi HLA,

Thanks again for helping me with this issue. Actually, I've just finished looking at the programming on the UHF radio that is attached to the rick and found that the dealer programmed the rec and xmit frquencies backwards.

Just for the sake of clarification, they are using a rick attached to a CM-300 and M-208 to cross band from 46 mhz to 453 mhz. Here's how it was set up.

Dispatch - remote CM-200 in the next town

Repeater - MTR-2000 on the FD's city water tower.

Cross band - At the same water tower with M-208 (low band) antenna on top of the water tower also, and a quarter wave antenna for the UHF CM-300 on top of the radio building under the water tower.

If I'm correct, this should work like the extender that I have from Will that I use to xband vhf-uhf, but with the frequencies backwards in the CM-300 attached to the rick, it would be like having two repeaters talk to each other.

Hope that makes sense.

I'm going to the site in the morning and swap the frequencies around and see if that works.

Thanks again

Bundy

HLA · Post by **HLA** » Tue Jan 02, 2007 6:30 pm

unfortunately if that don't work for you the only real solution is to get everyone on the same band or get use to and deal with the hang time.

bundy125 · Post by **bundy125** » Tue Jan 02, 2007 7:42 pm

Well, I went ahead and went to the tower and swapped the frequencies and that appears to have done it. I had one of their firefighters call on a low band handheld from about 5 miles out and they came in clear.... keying up the repeater. The only thing now is I get a constant carrier on the receiver of the uhf radio, that's not showing up on the mobiles, ht's etc... just the CM300 attached to the RICK and M208.

HLA, I do appreciate all your help with this. They are trying to get the money together to go all uhf, but are having to do it in stages. They also are trying to make use of the low band pagers as spares for the Minitor V's that keep crapping out.

Thanks again,

Bundy125

aaknitt · Post by **aaknitt** » Wed Jan 03, 2007 3:06 pm

bundy125 wrote: The hang time on the RICK evidentially was set at zero on installation. It appears that the repeater hang time is overriding the transmissions when they are trying to talk back to dispatch. Is there any solution short of adjusting the repeater hang time as it is about right for the UHF side of the system?

If I understand your system correctly, here's what is happening. If the channel is quiet and the FF keys on lowband, everything works fine. The crossband RICK transmits to the UHF repeater, and as soon as the FF lets off of the PTT switch on this lowband radio the RICK (which is set for zero hang time) stops transmitting. Now, however, the UHF repeater is still active due to the hang time, so what happens? The RICK retransmits the UHF hang time back over to low band. While that is happening, the lowband radio is in transmit mode, so it can't receive anything from the FFs in the field until the UHF repeater drops and the RICK unkeys the lowband radio. The only quick solution I can think of off the top of my head is to set the UHF repeater hang time to zero, as was already suggested.

Andy

Jim202 · Post by **Jim202** » Wed Jan 03, 2007 3:33 pm

There is one point that has not been made or the question
asked here. Does the repeater transmit CTCSS during the
hang time? If so, get that changed so there is no CTCSS
during the hang time. Then use the CTCSS to close the
RICK during the hang time. This will enable the LB to get
back in much faster.

Another point that I am not familar with the RICK enough
to know. On the vehicle repeaters I have played with
before they all went into monitor for a short time even
while repeating a signal. This provided for the ability of
the portable having control over the transmitter. In this
case, the LB radio would be the portable if the system
was connected the right way. This would allow the LB
side to interupt what ever was going on on the UHF side.

Jim

bundy125 · Post by **bundy125** » Wed Jan 03, 2007 3:56 pm

Hi aaknitt & Jim202,

The problem was the CM300 attached to the RICK was programmed with the repeater frequencies backward (if that makes sense).

Repeater receive freq = 458.XXX Repeater Out = 453.XXX

CM300 (RICK) receive =453.XXX CM300 Out = 458.XXX

In effect, the crossband unit and repeater were transmitting at the same time briefly during the repeater hang time and the low band units were never actually keying the UHF repeater. It was pretty much what HLA said in his last reply.... one repeater talking to another.

When I swapped the xmit and rec frequencies last night, that did the trick. The lowbands are now keying up the repeater and are able to cross talk just as if they were on the same band.

aaknitt, Jim202 & HLA, I really do appreciate y'alls help on this. The more I tried to figure out the problem, the more it confused me (which is probably evident in my previous posts in this thread). Sometimes you look at one thing so hard that you can't see the forest for the trees. Then folks like y'all help clarify and bring new perspective to the troubleshooting process.

My sincerest thanks,

Bundy125

aaknitt · Post by **aaknitt** » Wed Jan 03, 2007 7:33 pm

I was thinking about this some more and I have a new theory. My theory is that the UHF radio was originally programmed to correctly access the UHF repeater, which would lead to the scenario I described in my previous post and what you originally described. When you swapped the TX and RX frequencies, what you've done is bypassed the UHF repeater completely.

My guess is that your UHF radio (at the fire station or wherever) is within range of the dispatch center without needing to go through the repeater. Your UHF radio is now listening on the repeater input frequency, and transmitting on the repeater output frequency. You're able to talk to dispatch because they are listening to the repeater output frequency (as they should) and transmitting on the repeater input frequency (as they should). If this scenario is really what is happening, here are the consequences:

1) The lowband users will not hear all traffic on the UHF repeater. They will only hear the users of the UHF repeater that happen to be in range of the UHF radio at the fire station (or wherever it is that it's tied to the lowband radio).

2) The users monitoring the UHF repeater will only hear traffic from lowband users if the UHF users happen to be in range of the UHF radio at the fire station.

3) There is potential for interference if the UHF repeater is being used by users who are out of range of the UHF radio at the fire station. In this case, the lowband users won't know that the UHF repeater is in use, and could key up, which would cause the fire station radio to transmit on the repeater output frequency at the same time that the repeater is active, causing interference. Users will hear whichever station they happen to be closest to (repeater or fire station link).

If this is indeed what is happening (and I think it is), you should switch the TX and RX frequencies back to what they were to avoid this interference mess. To solve the original problem, Jim202's CTCSS suggestion is an excellent one, and the right way to do it. Get the UHF repeater to stop transmitting the CTCSS tone during the hang time and as long as your UHF radio at the fire station is set up for CTCSS decode, you'll be good to go. Actually, the problem could be on your end and not the repeater end. Make sure that the radio is set up for CTCSS decode as your first step...that could possibly solve the problem. If it doesn't, then you need to change the repeater as Jim202 suggested.

Other solutions include reducing the UHF repeater hang time, as mentioned earlier, or add a courtesy beep to the very end of the hang time and train lowband users to not talk until they hear the beep...that's not a very good solution though.

After just reading your last post, I think you're misunderstanding how to program a radio for use on a repeater. If the repeater receieves on 458.XXX and transmits on 453.XXX, all user radios should be programmed to transmit on 458.XXX and receive on 453.XXX. The repeater should be the only radio transmitting on 453.XXX. Right now it sounds like both the repeater and your CM300 are transmitting on 453.XXX.

If this isn't making sense let me know and I'll try to draw it out in visual form. You need to make sure you fully understand how the whole system works to avoid potential interference issues. Just because you can talk to dispatch once doesn't mean there aren't other system problems that won't surface later.

Andy

bundy125 · Post by **bundy125** » Thu Jan 04, 2007 3:52 am

Hi aaknitt,

The problem has been resolved, maybe I haven't been explaining it right (I've been working a lot of hours lately and getting very little sleep). The problem was... CM-300 attached to the RICK was programmed initially by the vendor in the following manner...

CM300 xmit - 453.xxx receive - 458.xxx (attached to the RICK)

Repeater xmit - 453.xxx receive - 458.xxx

My solution Tuesday night was to re-program the CM-300 attached to the RICK with...

CM300 ximit - 458.xxx receive - 453.xxx

The problem at this point appears to be solved. I apologize if my previous posts were confusing, but when I'm working on about 3 hrs sleep per day, I have a hard time collecting my thoughts and putting them in writing.

Again thanks to all who have weighed in.

Bundy125

aaknitt · Post by **aaknitt** » Thu Jan 04, 2007 7:01 am

Gotcha. So the UHF radio at the fire station was originally trying to talk to dispatch on the repeater output, but since the repeater was still active it overpowered the fire station radio and dispatch didn't hear anything.

If the RICK link is bidirectional, you still may run into the problem that I thought you had, which is where the repeater hang time keeps the lowband radio transmitting. However, since everything seems to be working properly, chances are that CTCSS is eliminating that condition.

Glad you got it working!

Andy