Crosstalk issue with LE, WX freqs. BC92xlt

[kjo1981]

I'm having an issue with crosstalk or interference on the primary frequency used by local law enforcement when scanning with my 92xlt. Freq. Is 154.86. Sometimes, I hear the local noaa wx radio walking on transmissions from the le dispatcher, only. This is frustrating, as this is the primary freq to monitor in my area.

I got the 92xlt to replace my ancient 200xlt. I didn't experience this problem with the older scanner.

 

[vwnut13]

I'm having an issue with crosstalk or interference on the primary frequency used by local law enforcement when scanning with my 92xlt. Freq. Is 154.86. Sometimes, I hear the local noaa wx radio walking on transmissions from the le dispatcher, only. This is frustrating, as this is the primary freq to monitor in my area.

I got the 92xlt to replace my ancient 200xlt. I didn't experience this problem with the older scanner.

Possible the dispatch has NOAA running in the room?

 

[kjo1981]

Possible the dispatch has NOAA running in the room?

I don't think that's the case. It's really bleeding over onto the LE freq. Makes the dispatcher hard to hear.

 

[WA0CBW]

Could it be intermod maybe from a paging transmitter? If it was really "bleeding over" there would be many complaints from other licensed adjacent channel users. Most scanners don't have good intermod rejection. Try turning the attenuator on and see if that helps.

 

[kjo1981]

Could it be intermod maybe from a paging transmitter? If it was really "bleeding over" there would be many complaints from other licensed adjacent channel users. Most scanners don't have good intermod rejection. Try turning the attenuator on and see if that helps.

At the risk of showing my ignorance, I'll say I had to Google "intermod". You are correct, the problem is on "my end". My previous scanner didn't blend the two transmissions together like this.

What is this attenuator and how do I activate on a 92xlt?

 

[WA0CBW]

kjo1981,
Sorry about that; you never know the experience level of the requester. Intermodulation distortion is caused by two or more signals (or their harmonics) mixing in the front end of a receiver causing it to hear frequencies that aren't really there. One way to reduce intermod is to make the receiver less sensitive to the strong signals. The attenuator reduces the signals getting to the receiver which might reduce the intermod. I'm not familiar with your model of scanner so it might not have an attenuator. Are you using an external/outdoor antenna instead of the standard handheld antenna? If so it might be that the external antenna if providing too much signal to the scanner causing the front end to be overloaded. Those are a couple of things to try.

 

[kjo1981]

kjo1981,
Sorry about that; you never know the experience level of the requester. Intermodulation distortion is caused by two or more signals (or their harmonics) mixing in the front end of a receiver causing it to hear frequencies that aren't really there. One way to reduce intermod is to make the receiver less sensitive to the strong signals. The attenuator reduces the signals getting to the receiver which might reduce the intermod. I'm not familiar with your model of scanner so it might not have an attenuator. Are you using an external/outdoor antenna instead of the standard handheld antenna? If so it might be that the external antenna if providing too much signal to the scanner causing the front end to be overloaded. Those are a couple of things to try.

It's just a small, handheld model. It's like the scanner isn't landing on the proper channel. When this happens, the display shows ch. 5 when it should be on ch 6. If I hit scan while listening to the traffic, it flips over to the correct channel.

It's not a big deal, but frustrating to have this problem with the scanner affecting the primary LE frequency that people monitor.

 

[rfburns]

If the radio does not have an attenuator (Sorry I can't find a manual for your radio) you can try a couple of things. Reduce the amount of signal at the antenna jack, by using a less efficient rubber duckie. Like one made for 800 MHz or a short stubby version. Reversing the order of chs 5 and 6 might help some so that the radio has a chance of stopping on the law ch before reaching ch 5 with the interference. Tightening the squelch could possibly help.

A more costly solution would be to purchase a Parr VHF SYM162HT notch filter to attach to the radio's antenna connector. Email Dale and I'm sure he can help you.

 

[kjo1981]

If the radio does not have an attenuator (Sorry I can't find a manual for your radio) you can try a couple of things. Reduce the amount of signal at the antenna jack, by using a less efficient rubber duckie. Like one made for 800 MHz or a short stubby version. Reversing the order of chs 5 and 6 might help some so that the radio has a chance of stopping on the law ch before reaching ch 5 with the interference. Tightening the squelch could possibly help.

A more costly solution would be to purchase a Parr VHF SYM162HT notch filter to attach to the radio's antenna connector. Email Dale and I'm sure he can help you.

I moved this freq from ch. 1 to ch. 6 just to see if it was something to do with that chan.

I did see a stub antenna for sale for this model the other day.

Some additional info: the LE frequency is 154.86. The interfering noaa broadcast originates from 162.425 just west of my town. I'm also located on the west side of town. When the problem happens, it displays ch. 5, which is state police. If I press scan, it switches over to 6 and the interference goes away. I hope that makes sense.

 

[kjo1981]

I've done a little more experimenting and determined that this crosstalk issue occurs on BOTH local LE freqs. The second one I scan is, I believe, a repeater. How could this be? I'm certain it's not an issue of dispatch having NOAA radio on in the backgroud.

I've tried scanning with the antenna removed and this seems to have solved the problem.

it is SO annoying to have this issue only with the primary local LE freqs. Is my scanner just broken? Is it a problem with my antenna?

ETA: info about antenna removal.

 

[fenderblue]

When this happened to me on my 396xt I seen what channel was getting bleeded and turned the attenuator on. It may it to more then 1 channel I think I around 6 of them. Found that this can happen more in the morning around 6-7 and then in same places in town. Weather conditions ie; humidty seems to be a factor also for me.

 

[fenderblue]

This happens to me with a external st-2 at home and a good multi-freq?? $50+ on my trunk lid.

 

[kjo1981]

Well with the antenna removed, I can hear the local dispatcher clearly, with no NOAA interference. But I do not have much range. Do you think a stubby antenna would be a happy median between the two? And would any stubby bnc antenna work?

 

[wtp]

try it

it can not hurt to try.
i keep one around for times i am too close to transmitters.
enjoy.

 

[kjo1981]

Further additional info: I have this issue on the main level of the house, but not in the basement. It seems like just a slight reduction in the efficiency of the receiver would do the trick.

I see there's a RS 1.7" stub antenna available from a few sources. That seems pretty short. Would that work, or should I look for one a little longer? Is a frequency specific antenna, such as an 800mhz, going to work, and give me more range than the stub? Looking for suggestions. Thanks

 

[kc0rzw]

I'm having an issue with crosstalk or interference on the primary frequency used by local law enforcement when scanning with my 92xlt. Freq. Is 154.86. Sometimes, I hear the local noaa wx radio walking on transmissions from the le dispatcher, only. This is frustrating, as this is the primary freq to monitor in my area.

I got the 92xlt to replace my ancient 200xlt. I didn't experience this problem with the older scanner.

I have that happen when a pd unit keys up within a couple blocks from my house. A less efficient antenna or one designed for another band may help with the issue.

 

[kjo1981]

Will halving the length of the antenna (going from 6" to 3"), have an appreciable effect, or should I go with the RS 1.7"?

Judging from the NOAA literature, I must be almost on top of the local Wx radio transmitter.

 

[kc0rzw]

Will halving the length of the antenna (going from 6" to 3"), have an appreciable effect, or should I go with the RS 1.7"?

Judging from the NOAA literature, I must be almost on top of the local Wx radio transmitter.

Could try a paper clip and see what happens. Do some experimenting.

 

[kjo1981]

Ordered a RS stubby online, seems like a good thing to keep around. Hopefully it works for me. Thanks, all for the assistance.

 

[kjo1981]

Got the Radio Shack stubby and it seems to have solved the problem. For $4.10, I'm pleased.

The added compactness and concealability is also nice.

Thanks again, everyone.