808 mhz RX on XTL?

[kb0uxv]

I am trying to track down some illegal carriers and wanted to program the repeater input, around 808mhz, into a XTL or XTS (mixed mode digital CSQ) to try and locate the offending signal. CPS does not like a RX freq in this range and creates an invalid. Anyone know of a work around? I have APX equipment available as well and have not tried to input 808mhz on that CPS, but I suspect the result will be the same.

 

[gsxxr1300r]

Unfortunately a service monitor is what has been used in past around here due to that issue, but with no real signal strength meter it is kinda worthless. Might be easier using an inexpensive scanner.

 

[tvsjr]

A service monitor? No real signal strength meter? You're joking, right?

 

[cyrus]

Try a spectrum analyzer with a directional antenna. It will allow you to characterize the offending signal as well as localizing it.

 

[KevinC]

To add to this, I would HIGHLY suggest a bandpass filter also. Most S/A's will overload (mixer saturation) in the vicinity of cell/ESMR sites.

 

[KevinC]

And since we're on the subject, here's my latest find...



You'd really be surprised how far 50 mW (supposedly) at 800.750 MHz will go.

 

[freerider-aust]

the info you are after is here https://www.p25.ca/threads/41-HOWTO-Change-Band-limits-(frequency-splits)-in-CPS also the apx bands are set in the firmware so you wont be able to change it

I am trying to track down some illegal carriers and wanted to program the repeater input, around 808mhz, into a XTL or XTS (mixed mode digital CSQ) to try and locate the offending signal. CPS does not like a RX freq in this range and creates an invalid. Anyone know of a work around? I have APX equipment available as well and have not tried to input 808mhz on that CPS, but I suspect the result will be the same.

 

[KevinC]

the info you are after is here https://www.p25.ca/threads/41-HOWTO-Change-Band-limits-(frequency-splits)-in-CPS also the apx bands are set in the firmware so you wont be able to change it

I'm pretty sure the filtering won't pass any 800 MHz reverse link frequencies, even if the CPS hack allows it.

But I could be wrong.

 

[gsxxr1300r]

A service monitor? No real signal strength meter? You're joking, right?

What I meant to say is that the Motorola radio doesn't have a signal strength meter. My bad...the young one broke my train of thought while I was typing.

 

[Notarola]

In had a similar problem a while ago what I ended up doing was to take a 800 duplexer and set the one bandpass to the offending freq then I used a uniden BCD996 scanner as the reciever with a scope program on a laptop to look at the signal modulation. I was able to track down the source of interfearance in an hour. The signal meter on the scanner along with the attenuator function served well all that was needed was to change the antenna to a 1/4 wave once I got full scale and remove it completely to finish the location. FYI it turned out to be a european modem used by a "new" resident to the country who had no idea his stuff was not legal here in this country.

I do have a spectrum analizer and a lot of other test equipment but this all sat on the seat of my car and was easy to look at while driving arround.

As another FYI Industry Canada was absolutly useless in helping.

 

[kb0uxv]

Thanks for the replies. I ended up figuring out the issue last night, one of the local shops was doing a PM at a sub-site a week ago and must have accidently reversed the channel bank v.24 cables between channels 7 and 8. I got the big clue last night when monitoring the output freqs with digital CSQ (when you alias the channel names its like zone watch in the field), duplicate audio was on both channels. Swapped the cables and all is now well.