Channel Bleed over

[kf6ywx]

We run two repeaters with the following freqs
Ch 1: Radio TX 469.825, Radio RX 464.825, DPL enabled
Ch 2: Radio TX 469.9625, Radio RX 464.9625, DPL enabled

When the weather gets hot, channel 2 bleeds on to channel 1 on the input side, which is to say that transmissions from handhelds on ch2 get repeated through ch1. This is a 25kHz bandwith system on both channels.

If I knocked our systemwide bandwith down to 12.5 kHz would this mitigate or resolve the problem?

ALSO

If I were to reduce ONLY the repeaters to 12.5 kHz, would it recive the 25kHz wide transmissions from the radios and would the radios get the repeaters ok? I've found it's VERY difficult to reprogram the entire fleet, though I can do it over time.

Thanks all!

[tvsjr]

No, swapping the repeaters to 12.5KHz wouldn't help matters much, and yes, you would need to reprogram both repeaters and the subscriber units.

This is not a programming issue, this is an RF conditioning issue. You need to walk through the RF conditioning with a service monitor (and someone trained to use it, if you're not... which I suspect to be the case) and see what's happening.

Describe your RF conditioning system and we can go from there.

[Jim202]

Your not exactly providing enough info to even start a
guess where the prtoblem may be. It wouldn't hurt
to provide the make and model num,bers of both
repeaters, what portables are being used and if the
DPL is the same for both repeaters. I can probably
guess that it is the same.

Next comes the tower issue. Is this a new tower, old
tower, rented site or do you own it.

Where are the antenna located? How far apart? What
type of coax is being used? Are the 2 repeaters combined
onto the same antenna? How old are the antennas?

What other radio systems are at the same tower site?

Are there any other towers near this location?

Are there any broadcast stations near by?

As you see, the info can go on and on. There could be
a multitude of things causing the problem. It goes from
poor grounds, loose hardware on the tower, bad antennas
bad coax cable, loose coax connectors, poorly tuned
transmitters and such.

Jim

We run two repeaters with the following freqs
Ch 1: Radio TX 469.825, Radio RX 464.825, DPL enabled
Ch 2: Radio TX 469.9625, Radio RX 464.9625, DPL enabled

When the weather gets hot, channel 2 bleeds on to channel 1 on the input side, which is to say that transmissions from handhelds on ch2 get repeated through ch1. This is a 25kHz bandwith system on both channels.

If I knocked our systemwide bandwith down to 12.5 kHz would this mitigate or resolve the problem?

ALSO

If I were to reduce ONLY the repeaters to 12.5 kHz, would it recive the 25kHz wide transmissions from the radios and would the radios get the repeaters ok? I've found it's VERY difficult to reprogram the entire fleet, though I can do it over time.

Thanks all!

[Jim2121]

since I've worked in Arizona (where at the end of this week we will have 3 digit numbers for temps...) and, were city, state, & gov. owned. We have contracts with AC, 24hr. service.... some of the ham's that can't afford AC. Use up to 3-4 muffen fans. but you should address the replies above my post 1st.

[escomm]

since I've worked in Arizona (where at the end of this week we will have 3 digit numbers for temps...) and, were city, state, & gov. owned. We have contracts with AC, 24hr. service.... some of the ham's that can't afford AC. Use up to 3-4 muffen fans. but you should address the replies above my post 1st.

PFFFFFT, we already have 3 digit temps here in LA (and brush fires to boot XD)

Seriously though, my first thought is that maybe his cans are heating up and going out of tune. But you are right, there are so many variables, and so many questions unanswered that it's impossible to definitively diagnose the problems at this point

[RKG]

At a minimum, though, if the Rx DPLs for the two channels are different, at least subscriber input on Ch. 1 should not cause the repeater on Ch. 2 to key up.

This, I stress, is where you start, not where you stop.

[misawatech]

I agree with RKG. I would believe that his DPL codes are the same.

I had a similar issue a few months ago. I had a direct net transmitting through a repeater. The direct frequency was 140.675 and the repeater receive was 140.725. Both pl codes were 103.5. We were able to change the freq and the pl code for the direct net to solve the problem but there still needs to be some checking done on the repeater and it's antenna system..

We control our own frequencies, to a point, here so I am constantly confused as to why we've had over half of our nets on the same pl codes?(103.5) Our band, what we are allowed to oeprate in, is 138-142 so you can guess some of the issues we are having.

[Will]

We run two repeaters with the following freqs
Ch 1: Radio TX 469.825, Radio RX 464.825, DPL enabled
Ch 2: Radio TX 469.9625, Radio RX 464.9625, DPL enabled

The TX and RX frequencies are upside down, you are suposed to TX on the 464 and RX at 469 in the repeater. BTW, the CH 2 is limited to two watts output.

AND, we DO need more information:

what duplexer model or description
what type of, and placement, on the antennas

[kg6bki]

Tucker...I say we go APCO 25..Come on...we can convince the boss together...XTS5000's for everyone

[Rayjk110]

We have the same issue at a school here. 464.675 and 461.800, with an R100 and GR500. They both use the same DPL tone of 371. We changed the DPL tone and the lame intermod went away.

I would either suggest changing the DPL on one or going to PL on another. Worked for us here.

[akardam]

We run two repeaters with the following freqs
Ch 1: Radio TX 469.825, Radio RX 464.825, DPL enabled
Ch 2: Radio TX 469.9625, Radio RX 464.9625, DPL enabled

The TX and RX frequencies are upside down, you are suposed to TX on the 464 and RX at 469 in the repeater. BTW, the CH 2 is limited to two watts output.

Looks like was talking about radio TX/RX, not repeater TX/RX. Standard +5mhz split, looks alright to me.

[Will]

[quote="akardam
Looks like ___ was talking about radio TX/RX, not repeater TX/RX. Standard +5mhz split, looks alright to me.[/quote]

Was NOT clear so I am making sure. Let's have the original poster confirm this..........

[tvsjr]

We have the same issue at a school here. 464.675 and 461.800, with an R100 and GR500. They both use the same DPL tone of 371. We changed the DPL tone and the lame intermod went away.

I would either suggest changing the DPL on one or going to PL on another. Worked for us here.

This is the WRONG answer! If one repeater is hitting the front end of the other bad enough to make it drop into transmit, the RF conditioning is HOSED. Changing the DPL will mask the problem, not fix it. If one repeater is hitting the other's front end that hard, you'll almost certainly suffer desense if both are in use simultaneously. You might even cook the front end.

Both your problem and the OP's problem need someone with some skill, time, and a service monitor/wattmeter/antenna analyzer/etc.

[Bruce1807]

yeah I always thought differnt PL/DPL's was for community repeaters and dense areas where you may have to share a frequency with another operator across town.

I mean the method above tells you that there is a desense issue at least

What repeaters are being used here.
I saw Rayjk110 mention a R100 and a GR500.
I wouldn't co-locate either of them wiyhn any other transmitter.
They suck for channel rejection

[tvsjr]

They suck for channel rejection

They suck in general!

[misawatech]

I read the original post again and wonder something else now.

When the weather gets hot, channel 2 bleeds on to channel 1 on the input side, which is to say that transmissions from handhelds on ch2 get repeated through ch1. This is a 25kHz bandwith system on both channels

He says that the handhelds get repeated through channel 2. Are there any mobiles or base stations and if so do they do the same thing?? It would be very odd that only the portables do this when it is hot and no other equipment. I have problems getting my portables to transmit through their own repeater let alone one they are not supposed to use. I refer you back to my first post about our oeprating freqs. We are so tight we are causing our own problems

[kf6ywx]

I've posted about other things and not seen a reply for years...but wow, that's a lot.

I'm running only handhelds on Ch.2, which is the channel that gets x-talked through 1, not the other way around. On channel 1 we have a CM200 mobile on a base config with a mobile antenna in the cieling pannels. There is one mobile in the truck, and the rest are handhelds: CP200's, CT250's (which make better paperweights than radios), MTS2000's and HT1000's.

I did drop both repeaters to 12.5 kHz, left the subscribers alone, and this helped a little. I've not noticed an issue since, and want to wait for a few weeks to see what happens overall before taking another step. I have access to a Motorola guy, but he's immensely busy. He's not thought that he needs to scope the place yet, but who knows.

I'm running a GR1225 on Ch.2, and an Icom FR-4000 on Ch.1. Both channels are DPL'd at 754, and it DID occur to me to change the DPL on Ch.2 fleetwide, but I know that this is a bandaid, not a solution.

Antenna towers are independent and on the roof about 100 yds appart. I don't know what kind of antennas they are save that they are unity gain.

Both repeaters are indoors, and thus relatively temperature controlled. Fans are in good working order on both boxes

To clarify, the 464 side is repeater output, 469 repeater input (which is why i hate the RX/TX language because you then must include a frame of referrence which I often leave out...)

Thanks for all your help

[misawatech]

I can speak from experience when I say that knocking only the repeater to narrowband may seem like it helps your problem. What it does though, in my opinion, is decrease your coverage. What you are doing now is forcing the portables to find a smaller hole in the in their respective channels. I may not be explaining to well but it is the same as changing the DPL codes. If you change one you must change them all.

The first thing you should do is get on the Motorola guys schedule and have him check your repeater and duplexer. If you repeater, and I assume, the duplexer is in a climate controlled environment then the weather is probably not a factor. I think if you could keep track you would find that the problems occur more frequently when the portables are in and around the repeater locations.

While it is true the weather will affect some duplexers it is not that common unless they have been tampered with. Your problem lies, as this thread noted, in the fact that your repeaters are probably becoming desensitized and not able to block the other frequency. This is whay you should hafve the motorola guy, or someone who is knowlegeable and has the proper equipment.

[thebigphish]

I did drop both repeaters to 12.5 kHz, left the subscribers alone, and this helped a little.

So you are transmitting a wideband frequency into a narrowband repeater setup...

i recall someone telling you NOT to do this. It will work... mostly.

'm running a GR1225 on Ch.2, and an Icom FR-4000 on Ch.1. Both channels are DPL'd at 754, and it DID occur to me to change the DPL on Ch.2 fleetwide, but I know that this is a bandaid, not a solution.

Dude, it's smarter to change your DPL's rather than go and mickeymouse your repeater to narrowband mode. You have your terminology backwards, your first move was the band-aid (and a bad one at that) ...and changing your DPL/PL will most likely solve your problem. It's not a band aid if it is the correct solution. Ever wonder why people use different PL's in crowded RF environments? It's to mitigate the EXACT problem you are experiencing, it allows repeaters to discriminate what they repeat. Put the repeater back in wideband, change the PL on one channel, reprogram the necessary units...and be done.

it is the right way

[tvsjr]

and changing your DPL/PL will most likely solve your problem

No, it won't. If the repeater output of one is hammering the front end of the second that bad, changing tones is merely a bandaid. What happens when a weak portable is talking through the Ch 1 repeater and someone keys up on Ch 2? The offending RF is still there... the Ch 1 repeater just ignores it due to the DPL. So, you get desense.

Service monitor.
Qualified technician.
Full review of the RF conditioning system.
Period.

[thebigphish]

Ok, after reading what i wrote late last night, (gotta check my sugar before i sit down) i would like to recant my previous statement, or at least amend it to include exactly what terry just said. I think i was thinking it in the grand scheme of things, and not forming that into my answer....

are there any filters being used btw?