Interference from one scanner to another

[Rawkee1]

In the past week, I'm beginning to get interference on my Radio Shack Pro 2067. It's very similar to the AM radio in the older cars that you used to put spark plus suppressors on to stop the noise. In my case it's my BCD 996P2 scanning that the RS is picking up. Both have separate outdoor antennas. This hasn't been a problem in the past, this just happened in the last couple of weeks and in doing a little research, it's definitely the Bearcat scanning. The static happens on the VHF frequencies, 155-162Mhz. If I stop scanning on the Bearcat, the static stops, however not using the BCD is not an option. I'm sure there is a reasonable explanation for this, but I can't figure it out. Is there a filter for this and if there is, where can I purchase one? Has any of you listeners ever encountered this???

 

[Ubbe]

Is it a ticking sound with about 100 ticks per second, equal the scan speed of the 996 or at a much slower rate?

Haven't you been doinf a lot of work with your setup lately and it happened after that?

What if you just disconnect the coax from the 996, still interference?

/Ubbe

 

[Rawkee1]

The ticking is really fast, but if I stop the 996 from scanning, the noise stops immediately. I haven't played with the set up at all. If I disconnect the coax from the 996, it goes away.

 

[kruser]

Step the 996 through each of the scanned channels manually one at a time and see if one of them causes the squelch to open on the 2067.
It sounds like the local oscillator may be getting into the 2067 from the 996 due to the antennas being near each other. Why it just started if you made zero changes to your setup or programming is a mystery though.

If it's just one frequency on the 996 that causes the squelch to open on the 2067, lock that one out if possible. Maybe you could let the 2067 scan the interfering frequency from the 996 if it is just one frequency causing the problem.

You might also try running the 996 and maybe even the 2067 from a temporary battery hookup for power to rule out odd noise coming from the stupid switching type wall warts Uniden uses these days. Unplug the 996 wall wart during the test of course!

Also, even though disconnecting the antenna from the 996 stops the noise, how close are the two scanners to each other? If sitting on top of each other, separate them from each other by a few feet or so and test again with their antennas hooked up normally.

 

[Rawkee1]

They are about 2' apart as they always have been. The antennas are on the same mast on the roof. One antenna is a VHF high band and the other antenna is a Diamond Discone D130

 

[kruser]

They are about 2' apart as they always have been. The antennas are on the same mast on the roof. One antenna is a VHF high band and the other antenna is a Diamond Discone D130

Did you try to narrow it down to it just being when the 996 is on a certain frequency?
I used to have a very similar issue that only happened when one of the scanners passed by a certain frequency. So on the other scanner you heard the fast pulsing noise of the squelch opening and closing rapidly as the frequency was scanned. Once I manually found which frequency caused the problem, I was able to lock it out and solved the problem. In my case I was lucky as the bad frequency was not an important one.

 

[Rawkee1]

Thanks, I'm going to do some investigating today. Funny how that works, NOT.

 

[spacellamaman]

just start shuffling movable components around til it stops, its the quickest easiest way to do it, as it has been the bane of my existence.

 

[wtp]

give each radio a different corner of the room...
i only had to shuffle a couple of frequencies around to cut this way down.

 

[Ubbe]

If I disconnect the coax from the 996, it goes away.

Then it's interfering between antennas and not between scanners, if the coaxes are full length and not spliced somewhere where it could leak our RF.

Scanners always leak out RF from its antenna port so it could be that you have changed some settings in either scanner to include a priority/closecall function or new frequencies to scan. It could also be that either scanner needs to have it grounds redone, be unscrew a half turn and re-thigh each screw at the circuit board inside.

/Ubbe

 

[ecps92]

Please follow Krusers advise first, it sounds like one of the scanners on a specfic frequency is generating RF into the other scanner.
Lets rule that out first, by stepping thru Each and EVERY frequency programmed in the radio to ID what is generating the RF

And for the folks who say "put each baby in their own corner" - I've had this occur with radios in different parts of the house in the past
and the only solution was to lock out the channel on the offender or put the radio in a Faraday Cage [not helpful]

Thanks, I'm going to do some investigating today. Funny how that works, NOT.

 

[spacellamaman]

put the radio in a Faraday Cage [not helpful]

out of curiosity, was using the cage not helpful or was the cage not helpful in and of itself due to not working? I know same question twice, I ask cause i have tried various things over the years with very spotty results, ammo cans, xmas popcorn tins, scanner double bagged with ziplock bags and foam as standoffs and multiple outer layers of aluminum foil (cause if its silly and it works, it still works right? otherwise its just a foil ball with a flexible whip out the top, irresistible to cats might i add).

any advice on functional Faraday cage would be much appreciated.

anyway, thanks

 

[wtp]

try back of the set antenna/s...?

 

[ecps92]

Worked, to eliminate the issue, however caused more problems that just deleting the offending frequency. Recommend 1000%

P.I.T.A. to use buttons, reprogram, adjust the volume etc - just ID the offending channel and delete it.
and besides that just plain bulky/ugly

out of curiosity, was using the cage not helpful or was the cage not helpful in and of itself due to not working? I know same question twice, I ask cause i have tried various things over the years with very spotty results, ammo cans, xmas popcorn tins, scanner double bagged with ziplock bags and foam as standoffs and multiple outer layers of aluminum foil (cause if its silly and it works, it still works right? otherwise its just a foil ball with a flexible whip out the top, irresistible to cats might i add).

any advice on functional Faraday cage would be much appreciated.

anyway, thanks

 

[R8000]

It is my understanding that multicouplers like the MCA208 Scannermaster offers has the feature where it isolates from port to port to prevent this. Text from the description reads "Isolation will reduce the possibility of RF interaction between receivers caused by local oscillators, synthesizers, etc. ".
Perhaps just using one antenna with a proper scanner receive multicoupler will solve this issue. This is one of the main reasons products like this are desireable vs just using a "T" splitter or CATV amps...etc.
Just a thought to consider.

 

[spacellamaman]

Worked, to eliminate the issue, however caused more problems that just deleting the offending frequency. Recommend 1000%

P.I.T.A. to use buttons, reprogram, adjust the volume etc - just ID the offending channel and delete it.
and besides that just plain bulky/ugly

feel like passing along the style/type/design of your faraday cage? my big ball of tin foil causes all the kids to make fun of me.....

 

[ecps92]

too many varieties starting [Pails, Chickenwire, buckets, bread boxes etc] back in my HS Days [80's] into College, again it was easier to just delete the offending freq from one radio and leave it in the other, no need of dueling scanners.

feel like passing along the style/type/design of your faraday cage? my big ball of tin foil causes all the kids to make fun of me.....

 

[buddrousa]

Or the simple answer use the correct tool for the job.
I run 16 to 25 scanners through Stridsbergs no loss no interference like I had trying to use cable TV junk.

 

[wtp]

from his first post.
" Both have separate outdoor antennas "
so we can rule out splitters/combiners/T and other items.
maybe it is through the power supply.
he wanted to know if someone had the same thing happen.

 

[ecps92]

or likely just RF from the device itself, since a scanner is a set of oscillators, essentially a QRP transmitter and if the right combination of frequencies appears it will effectively transmit within the residence and lock-up the other RX device.

I used to do that to my Brother when he was listening to his AM Radio, by taking another Radio and tuning 455 khz lower than his channel.
Sometimes it would drown out his reception other times made for a nice hetrodyne

Too many cooks in this broth, how about we let the OP try the first suggestion, then if we don't have a resolution you can each add your favorite spice to the broth.

from his first post.
" Both have separate outdoor antennas "
so we can rule out splitters/combiners/T and other items.
maybe it is through the power supply.
he wanted to know if someone had the same thing happen.