How is it happening?

[SLWilson]

Ok techs, help me out here.....

We are in Gallia County, a small SE Ohio county.

I got a call from Lincoln County, WV a couple of days ago telling me that we were bringing their repeater up and they could hear us dispatching calls.

Lincoln County, WV is approximately 55 - 60 air miles from us.

Their VHF Hi repeater operates on 151.010 with a DPL (I can't remember what though)..

We have NOTHING in our county near that freq. We have nothing with a DPL. All of our stations use a standard PL tone.

They are saying that it is our city PD repeater that is bringing up their VHF repeater. Our PD repeater is a 20 watt UFH radio with 458.850 as the input with 225.7 as the PL. The output of the repeater is 453.850 with the same PL tone (225.7)....

We had our radio service folks PM the repeater today. We have no harmonics. We have no spikes. We have 18 1/2 watts out with a 3 db gain antenna and no visible reflected power. We're licensed at 20 watts out with a 60 watt ERP. Our repeater is at an elevation above sea level at around 860 feet with the antenna up about 50 feet on the tower.

We use a 20 watt Motorola M1225 from the 911 Center to "key" the repeater to dispatch the city PD with. That antenna is an omni gain antenna. The radio checks OK with no reflected power.

In looking at the FCC list for Lincoln Co, WV, it looks like they are using UHF links to "control" their VHF Hi band base. Their tech tells us they use a DPL on the link and that it is working properly. Now, at their Hart's tower site (near the Cabell Couty line - two counties away from us), they ARE using the 453.850 and 458.850 combo (with a DPL) on THAT particular link.

This problem (according to them) started about three weeks ago.

We have NOT had any modifications done on our end to any of our equipment in that timeframe.

Here's the REAL kicker!!! This afternoon, we TURNED OFF our UHF repeater. We then keyed up our control point (from the 911 Center) and low and behold, we brought up THEIR VHF Hi band base. Our control point antenns is at about a 630 ft elevation above sea level with the antenna up about 30 feet on the tower.

So, we've determined that the "offending" frequency to them is our transmitted 458.850 with a PL of 225.7

What is even crazier, from downtown Gallipolis (elevation around 530 feet) any MOBILE radio transmitting on 458.850 will BRING UP their tower site!!!!

Again, I ask, any tech guys out there have any thoughts?

I asked their service tech if it was possible that they'd "lost" their DPL at their link site. He says not. I asked if it was possible that they'd worked on the link site and left the DPL turned off. He says no....

I'm listening. Need help. This one has me stumped !!!!

Steve/Gallia

 

[mtindor]

Can any MOBILE (without PL turned on) key up their repeater? If so, then their techs are wrong and they need to get a clue. Can any MOBILE (with a particular PL but one that isn't their PL) key up the repeater? If so, then their techs are wrong and they need to get a clue.

I think once your techs came out and checked things, and then especially after you noticed that any mobile xmitting on 458.85 would key up their repeater via one of their control links, you essentially put the ball in their cart. Find out where those techs got their skooling.

Actually now that i read that, you're saying your repeater (output 453.85) keys up their repeater AND any mobile (output 458.85) keys up their repeater? Could it be that 458.85 really is the only one keying up their repeater, that your mobiles, etc. are keying up their repeater and they are confusing it with your repeater keying theirs up? At any rate, if I can to downtown Gallipolis, key up on 458.85 and bring up their repeater, that's not your fault. That's a problem on their end.

Can you key up their system by xmitting on 458.85 without a PL?

Mike

Ok techs, help me out here.....

We are in Gallia County, a small SE Ohio county.

I got a call from Lincoln County, WV a couple of days ago telling me that we were bringing their repeater up and they could hear us dispatching calls.

Lincoln County, WV is approximately 55 - 60 air miles from us.

Their VHF Hi repeater operates on 151.010 with a DPL (I can't remember what though)..

We have NOTHING in our county near that freq. We have nothing with a DPL. All of our stations use a standard PL tone.

They are saying that it is our city PD repeater that is bringing up their VHF repeater. Our PD repeater is a 20 watt UFH radio with 458.850 as the input with 225.7 as the PL. The output of the repeater is 453.850 with the same PL tone (225.7)....

We had our radio service folks PM the repeater today. We have no harmonics. We have no spikes. We have 18 1/2 watts out with a 3 db gain antenna and no visible reflected power. We're licensed at 20 watts out with a 60 watt ERP. Our repeater is at an elevation above sea level at around 860 feet with the antenna up about 50 feet on the tower.

We use a 20 watt Motorola M1225 from the 911 Center to "key" the repeater to dispatch the city PD with. That antenna is an omni gain antenna. The radio checks OK with no reflected power.

In looking at the FCC list for Lincoln Co, WV, it looks like they are using UHF links to "control" their VHF Hi band base. Their tech tells us they use a DPL on the link and that it is working properly. Now, at their Hart's tower site (near the Cabell Couty line - two counties away from us), they ARE using the 453.850 and 458.850 combo (with a DPL) on THAT particular link.

This problem (according to them) started about three weeks ago.

We have NOT had any modifications done on our end to any of our equipment in that timeframe.

Here's the REAL kicker!!! This afternoon, we TURNED OFF our UHF repeater. We then keyed up our control point (from the 911 Center) and low and behold, we brought up THEIR VHF Hi band base. Our control point antenns is at about a 630 ft elevation above sea level with the antenna up about 30 feet on the tower.

So, we've determined that the "offending" frequency to them is our transmitted 458.850 with a PL of 225.7

What is even crazier, from downtown Gallipolis (elevation around 530 feet) any MOBILE radio transmitting on 458.850 will BRING UP their tower site!!!!

Again, I ask, any tech guys out there have any thoughts?

I asked their service tech if it was possible that they'd "lost" their DPL at their link site. He says not. I asked if it was possible that they'd worked on the link site and left the DPL turned off. He says no....

I'm listening. Need help. This one has me stumped !!!!

Steve/Gallia

 

[SLWilson]

Can any MOBILE (without PL turned on) key up their repeater? If so, then their techs are wrong and they need to get a clue. Can any MOBILE (with a particular PL but one that isn't their PL) key up the repeater? If so, then their techs are wrong and they need to get a clue.

Actually now that i read that, you're saying your repeater (output 453.85) keys up their repeater AND any mobile (output 458.85) keys up their repeater? Could it be that 458.85 really is the only one keying up their repeater, that your mobiles, etc. are keying up their repeater and they are confusing it with your repeater keying theirs up? At any rate, if I can to downtown Gallipolis, key up on 458.85 and bring up their repeater, that's not your fault. That's a problem on their end.

Can you key up their system by xmitting on 458.85 without a PL?

Mike

Hey Mike,

What I "think" we determined is that OUR mobiles transmitting on 458.850 using OUR PL of 225.7 will bring their VHF Base on the air. THEY originally thought and told us that it was our REPEATER doing it. But, we turned the repeater OFF and then brought up their link with our control point from the 911 Center AND with mobile radios at various points within Gallipolis (with our PL).

I'm tending to agree that we DO NOT have an issue that we need to address as far as causing harmful interference to them. I think they have a RX issue in their link RX radio. But, I was wanting to hear that from others as well!!!!

Steve/Gallia 911

 

[mtindor]

Hey Mike,

What I "think" we determined is that OUR mobiles transmitting on 458.850 using OUR PL of 225.7 will bring their VHF Base on the air. THEY originally thought and told us that it was our REPEATER doing it. But, we turned the repeater OFF and then brought up their link with our control point from the 911 Center AND with mobile radios at various points within Gallipolis (with our PL).

I'm tending to agree that we DO NOT have an issue that we need to address as far as causing harmful interference to them. I think they have a RX issue in their link RX radio. But, I was wanting to hear that from others as well!!!!

Steve/Gallia 911

Well, I'm neither an RF Engineer or a standard radio tech, but I think you've pretty much nailed it as being their issue and not yours. It all sounds like somebody's (read: their techs) unwillingness to admit a problem (read: letting pride get in their way OR letting laziness get in thier way). Sad isn't it? I think so.

For curiosity's sake you might want to see if your mobiles (minus PL) can bring up their link. It would be interesting to know if they just have a wrong PL or no PL at all.

Mike

 

[kc8qch]

Something Else

Here's a thought too. If you are tramsitting on UHF and they are on VHF how are they able to hear you? you may want to check that some wanker isn't using a crossband repeater and repeating your signal into their system.

 

[N8IAA]

Here's a thought too. If you are tramsitting on UHF and they are on VHF how are they able to hear you? you may want to check that some wanker isn't using a crossband repeater and repeating your signal into their system.

Sounds more probable that this is the problem. I used to help a group up in the Greater Cleveland area hunt down the perps that were doing that via ham radio. We were cops, fd, and hams. It kept the idiots from continuing their transmitting. I am sure that there is some in Gallia that will help hunt done the perp.

N8IAA

 

[SLWilson]

Update....

Here's a thought too. If you are tramsitting on UHF and they are on VHF how are they able to hear you? you may want to check that some wanker isn't using a crossband repeater and repeating your signal into their system.

OK....We've sort of gotten to the bottom of it. Here goes....
They use a UHF link to "key" their VHF Hi band base station. Just so happens that their UHF link (they didn't tell me any of this originally) is set up to operate on the SAME input and output as the Gallipolis PD's UHF repeater. That's 458.850 Input with a PL of 225.7 and an output of 453.850 (PL225.7)...As I understand it, they had THEIR link radio at their tower site worked on a week or so ago. It was SUPPOSED to operate with a DPL. I think the tech left the DPL "disabled" when he got done. So, everything we transmitted from here, EVEN THOUGH we are over 55 AIR MILES away from them, brought up the VHF transmitter!!!!

For now, the puzzel has been solved.

Steve/Gallia 911

 

[N8IAA]

OK....We've sort of gotten to the bottom of it. Here goes....
They use a UHF link to "key" their VHF Hi band base station. Just so happens that their UHF link (they didn't tell me any of this originally) is set up to operate on the SAME input and output as the Gallipolis PD's UHF repeater. That's 458.850 Input with a PL of 225.7 and an output of 453.850 (PL225.7)...As I understand it, they had THEIR link radio at their tower site worked on a week or so ago. It was SUPPOSED to operate with a DPL. I think the tech left the DPL "disabled" when he got done. So, everything we transmitted from here, EVEN THOUGH we are over 55 AIR MILES away from them, brought up the VHF transmitter!!!!

For now, the puzzel has been solved.

Steve/Gallia 911

What ddo you expect from West By God Virginia;>))

 

[16b]

I'm not surprised about the DPL being disabled. They're probably using a radio with a monitor button on the front and the radio dude either bumped it or turned it off on purpose and forgot to turn it back on.

55 miles away... they must have a pretty spiffy antenna for their link receiver.

 

[SLWilson]

Just a guess....

I'm not surprised about the DPL being disabled. They're probably using a radio with a monitor button on the front and the radio dude either bumped it or turned it off on purpose and forgot to turn it back on. 55 miles away... they must have a pretty spiffy antenna for their link receiver.

If I had to hazard a guess, I'd say they have a RX amp on it, but, I could be wrong....I've programmed in their actual VHF freq here and can barely hear it unless I head to a hilltop. But, our UHF mobiles could bring it up from the middle of downtown Gallipolis!!! THAT'S the part I find hard to understand....Anyway, it's NOT happening now. I checked with their director yesterday morning. Their tech "fixed" it as soon as he left here Friday evening!!!! Imagine that !!!! Steve :lol: