VCall10 (155.7525) Interference

[bgottschallberks]

We are trying to locate the source of interference being received on 155.7525. This is being received in Lancaster County and Berks County, PA for certain, and manifests itself as continuous carrier with a rhythmic tapping noise. We have a couple dozen hours invested with FCC trying to DX the signal with no luck as we cannot find the signal at ground level. It is being received on numerous tower top antennas. Hoping someone will see this and be closer to the source and able to get us a bead. It has been going on for days and seems to be less present when the ceiling is high in the areas noted above. Also, it is on PL at 156.7.

Thanks in advance for any help.

 

[RFI-EMI-GUY]

Time for a chopper ride.

 

[wtp]

when i lived in new jersey i would get some strange stuff on 155.73.
turned out to be cable leakage from 155.75,
that seems pretty close.
and the reason it is not DF able is that it could be a little from everywhere.

 

[u2brent]

possible, but with a matching CTCSS/PL 156.7?
more likely a legit/semi-legit source that's gone awol?

 

[SVFC462]

 

[RFI-EMI-GUY]

If it were me doing this, I would get a 3 element VHF yagi and drive to the top of every parking garage I can find and try to get bearings from all of them. You will need a sensitive receiver and step attenuator, or spectrum analyzer, preamp and a VHF band pass filter. Or all of the above. I had an 800 MHz signal once that indeed was coming from everywhere (because it was mass produced) and only once in a helicopter I could be line of sight to find one.

If in this case it a base station or mobile somewhere, the power levels should be such that you can get some headings.

 

[RFI-EMI-GUY]

when i lived in new jersey i would get some strange stuff on 155.73.
turned out to be cable leakage from 155.75,
that seems pretty close.
and the reason it is not DF able is that it could be a little from everywhere.

Been there done exactly that once a long time ago. The cable TV guys were very helpful.

 

[E-542]

I'm located near the intersection of Dauphin St & Pershing Ave in Lancaster City, PA(Just fo ra overal idea of receiving), using a BCD436HP, with the old Radioshack 800MHz antenna.
I've never recieved ANYTHING on VTAC10, and that is *always* in my scan list as well as the other UHF, 700, and 800MHz National Interop channels. Also usually am receiving from the 2nd story of a home here, and out and about in the city.
Hope that's a help to pinpointing this.
Only thing I ever get on the Interop side is under the Public Safety Common - UHF MED Channels, of a morse-code ID here and there on MED-6 of 463.1250

 

[djshadowxm81]

@bgottschallberks Hey for what its worth Brian, (Former berks countian here). I checked at our radio clubs high profile site yesterday I swung the beam over towards Lancaster and Berks (Not sure if mountains may be blocking toward Ephrata or not) but I did not hear anything on VCALL10. Nothing with a carrier just noise floor that's it. So we're not seeing it in York, if that helps narrow it down. We tested from Rocky Ridge in York.