PRO-106 800mhz interference

[kittyranma]

I bought a PRO106 exactly 30 days ago. It's going back today because of this awful interference I get only on 800mhz. All the systems are trunked, and it's both on Mot-II and EDACS. And also, it's both on a local system (San Francisco, where I live) and remote systems (Oakland and BART subway system). This is only on 800mhz. I don't have problems with UHF or VHF (but the Air reception is awful -- not very sensitive at all).

The interference is a buzzing sound when I hold the radio in the "right position". With the attenuator (ATT) on, the reception is good (not the best), but the buzzing sound is gone. I have tried outside my apt (just in case of local interference) and 15 miles away from San Francisco (near the airport to test Air reception), and the same buzzing is there as long as I don't use the ATT.

P25 reception is fine, no buzzing of course. And P25 reception is good (can get San Mateo Sheriff Mot-II P25 system just fine in San Francisco).

I have a demo of this on Youtube at YouTube - PRO-106 800mhz interference

Anybody have any ideas? Thanks in advance!

 

[OsloViking1975]

I bought a PRO106 exactly 30 days ago. It's going back today because of this awful interference I get only on 800mhz. All the systems are trunked, and it's both on Mot-II and EDACS. And also, it's both on a local system (San Francisco, where I live) and remote systems (Oakland and BART subway system). This is only on 800mhz. I don't have problems with UHF or VHF (but the Air reception is awful -- not very sensitive at all).

The interference is a buzzing sound when I hold the radio in the "right position". With the attenuator (ATT) on, the reception is good (not the best), but the buzzing sound is gone. I have tried outside my apt (just in case of local interference) and 15 miles away from San Francisco (near the airport to test Air reception), and the same buzzing is there as long as I don't use the ATT.

P25 reception is fine, no buzzing of course. And P25 reception is good (can get San Mateo Sheriff Mot-II P25 system just fine in San Francisco).

I have a demo of this on Youtube at YouTube - PRO-106 800mhz interference

Anybody have any ideas? Thanks in advance!

I see you have the rubber duckie antenna on there. Sometimes an 800MHz antenna will help that and increase decibal gain. Radioshack has them for like 20.00 bucks.

 

[TrenchFeeder]

That could either be a flaw in the individual radio, or due to high density of the airspace, which would explain the ATT stopping the buzz.

I have a pro 164 and dropped it onto concrete hard, a few times, and it doesn't have anything like that.

When you take it back ask to sample a similar model if they will let you, that way you'll know if it's the breed, or the unit

 

[KC5EIB]

What you are decribing is the typical "Nextel (IDN)" interference which is the reason for rebanding. Short of moving away from the interfering cell site, using the attenuator or moving the radio are the best options.

 

[RadioDaze]

I frequently experience the same thing here in Orange County. And if I move my fingers up and down the antenna to "retune" it, the problem goes away when I find the sweet spot.

On second thought, all of that sounds rather suggestive, the way I've worded it.

 

[KB3SJV]

Same problem with my Pro-96 in Montgomery County pa. I do have the $20.00 radioshack antenna, but that didnt solve the interference. Ive never tried to find the "sweet spot", as described by Radio Daze!!! sounds interesting

 

[krokus]

The 800MHz antenna will not help you, as your are receiving 800MHz interference. I would think it is either Nextel, as pointed out already, or possibly even a digital 800MHz trunking system. There is also a chance you still have one of the few analog 800MHz cell sites around, and that is the control channel. (Not all of the systems went dark, a few were left functional.)

The P25 system is not noticeably affected for one of three reasons:
1) There is sufficient bandspace between the signals that the P25 signal is not affected.
2) The P25 signal is strong enough that it overcomes the interference.
3) The interference is the P25 control channel.

What floor are you on, in your building? Where are the cell/Nextel sites near there? Attenuation, either by distance or inserted loss, or filtering are your only real options.

 

[kittyranma]

What floor are you on, in your building? Where are the cell/Nextel sites near there? Attenuation, either by distance or inserted loss, or filtering are your only real options.

I am on the 10th floor. I have a nice view of downtown San Francisco. So I can definitely "see" lots of radio sites. Don't know which are Nextel, but I will assume there are plenty nearby. But again, I also had this interference 15 miles away near SFO airport.

I forgot to mention that I had a Uniden 396xt (not the XLT) from Fry's for a couple of weeks (also returned). I did not have the interference on that radio, but the sensitivity was not as good, and the P25 decoding was horrible for the San Mateo system I demoed on the Youtube video. As mentioned here before, the PRO-106 has killer sensitivity.

I'm hearing here that this is a common problem for the 106. Which is too bad since I wanted to come back into scanning after a 6 year hiatus. Is it worth trying out a different radio (as mentioned) or a 396XLT?

 

[rfradioconsult]

What you are experiencing is indeed interference from a NEXTEL site, as you move around the area you can find spots were reception is ok but other areas that you pickup the interference; NEXTEL uses multiple sites, roughly a 1-2 miles apart. If you live in a high-rise building there is a chance there may be a site on your rooftop.

This problem may manifest it's-self in any other scanner and changing a model may or may not improve receiption. What you are experiencing is why Sprint is paying Billions of dollars to re-band the 800 MHz spectrum.

 

[Nester17109]

Dont see what the major problem is just leave the ATT on.

 

[KB3SJV]

When Im outside or in my car is the only time i have interference, my portable, and base radios come in perfect indoors. leaving the attenuator on solves the problem when im outside or driving, but in the house i wont be able to copy any transmissions.

 

[slicerwizard]

Anybody have any ideas?

Yes, it's classic overload/desense. Use the scanner the way it was designed to be used - attenuator on (for 800 MHz channels at least) in noisy urban environments, attenuator off when you're out in the quiet boonies. If the built in attenuation is too much for your liking, leave the attenuator off and use a one inch paperclip as an antenna instead.

You should be able to figure out where the interference sources are - there's gotta be a website or two that lists cellular site locations around you. And FYI, an airport is the last place you should expect to find a low noise floor.

 

[n5usr]

I get the same thing, can't wait for rebanding! I can always tell when I'm approaching a Nextel tower when driving around, as that noise starts getting louder. There are a couple of the towers that are so strong they overwhelm the scanner even with the attenuator on. For about a half mile around both of them I can't hear a thing.

For the system I listen to, not all of the voice channels are near (active) Nextel frequencies. A single conversation can bounce between crystal clear and unlistenable as the system switches the people talking between different VCs.