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General Scanning Discussion - For general questions not specific to a model of scanner or general discussion of use of a scanner. Manufacturer specific posts should be directed to the appropriate forums below and location specific posts should go in the appropriate regional forum..

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Old 08-12-2017, 2:01 PM
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Default What am I doing wrong??

So here is a tricky one for you all to chew on.
I purchased a couple of yagi antennas for Mass State Police freq. I put them up at 90 feet on a tower pointing direct at the appropriate troop sites (Milton and Middleboro). They were first connected to LMR-4-50. No trunk signal T nothing. OK so maybe I had bad cable?? I run new RG-6 still no signal. OK bad antennas?? So I take radio (RS-197) up to 90 feet and connect 6 foot jumper of LMR-400 to antenna(s) and radio. Still nothing heard and no T. Disconnected antenna with just 6 foot jumper plugged into radio at 90 feet came in loud and clear. R-9+
Stymied now back on the ground. I connect yagi to 6 foot LMR jumper point in direction of Milton. Nothing !! Now I am pissed I set yagi on the ground works fine. Put on 6 foot PVC and hold it in the air, nothing. I am like WTF is going on here!! Works on the ground but not in the air?? Just for shorts and goggles I connect a Tram 800 NMO antenna. Set on the ground works fine. Touch the ground teeth to tower nothing. Taped it to PVC put 6 feet in air nothing.
This entire event is so counterproductive to what I know about radio and radio signals. I am pulling my hair out of my head. Took down LMR, RG-6 packed my stuff in my truck and called it a two day failure.
Any suggestions??
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Old 08-12-2017, 2:43 PM
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What have you done to prove the scanner can hear anything other than the state police.? I would try to see if you can hear your local NOAA weather station up at the 162.xxx that covers your local area.

If that works, then I would try another trunking system near you. try looking at the state listings to see what might be near you.

Bottom line here is you have too many unknowns to even start pointing a finger to where the problem is.

Is it the antenna?

Is it the coax cable?

Is it possible the scanner is broke at the frequencies your trying to listen to?

Is it possible that the signals are to weak to be able to receive them?

You need something to help reduce the amount of unknowns on this problem. Maybe another receiver that can listen to the frequencies your trying to listen to.

Let the group here know what you found out was the problem. We all learn from problems that others have.
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Old 08-12-2017, 2:45 PM
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What kind of receiver are you trying? You got others to test? Always use a variable attenuator when dealing with scanners. And when in doubt why there is no reception always force the scanner into analog FM mode and listen to how the signal sounds, if any.

/Ubbe
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Old 08-12-2017, 2:48 PM
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My guess is that you've got some signal overloading the receiver and desensing it.
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Old 08-12-2017, 3:59 PM
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I posted in the threat a RS-197. NOAA works fine as does conventional FM signal. For some reason I am missing something. Tried all new coax, Two kinds, two diff types of antennas for the band.
It works with the antenna physically laying on the ground in the crushed stone but not at 90 feet.
The two sites I picked are the closest sites that come in fine on the ground (literally)
It also works beautiful at 90 feet with a 6 foot section of LMR-400 sticking out of the radio connected to nothing at 90 feet. Puzzled !! I eliminated all the unknowns switched radios, antennas and coax
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Old 08-14-2017, 8:31 PM
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Sounds like strong signal desense

And if you are receiving a S9 perfect signal with a un terminated coax jumper you obviously don't need a beam antenna

You can buy a SDR radio for under 10 dollars that will show you exactly what nearby transmitters are desensing your receiver

Then you can use filters to reduce them
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Old 08-14-2017, 8:38 PM
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I had a 197 hooked to a 4 bay VHF on a water tower and experienced similar results. I think they simply get swamped with so much RF and go deaf.
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Old 08-16-2017, 3:30 AM
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If you don't bother to get a $10 variable attenuator, that almost guaranteed would solve your problem, you could at least try the fixed attenuator in the scanner.

/Ubbe
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Old 08-16-2017, 6:18 AM
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So... with everything connected and raised, Nothing.
Take down and lay on ground and all is fine ? Great Reception ?

Might just be a grounding issue or a shorted cable/connection

BTW, from Brockton, for Zone 3 point toward Norwell vs Middleboro

However a Yagi for the Analog Simulcast sounds like over-kill
Reception of Zone 3 and Zone 5 have generally not been a reported issue
on Omni's or experiencing the P25 Simulcast issues
Quote:
Originally Posted by sdu219 View Post
So here is a tricky one for you all to chew on.
I purchased a couple of yagi antennas for Mass State Police freq. I put them up at 90 feet on a tower pointing direct at the appropriate troop sites (Milton and Middleboro). They were first connected to LMR-4-50. No trunk signal “T” nothing. OK so maybe I had bad cable?? I run new RG-6 still no signal. OK bad antennas?? So I take radio (RS-197) up to 90 feet and connect 6 foot jumper of LMR-400 to antenna(s) and radio. Still nothing heard and no “T”. Disconnected antenna with just 6 foot jumper plugged into radio at 90 feet came in loud and clear. R-9+
Stymied now back on the ground. I connect yagi to 6 foot LMR jumper point in direction of Milton. Nothing !! Now I am pissed I set yagi on the ground works fine. Put on 6 foot PVC and hold it in the air, nothing. I am like WTF is going on here!! Works on the ground but not in the air?? Just for shorts and goggles I connect a Tram 800 NMO antenna. Set on the ground works fine. Touch the ground teeth to tower nothing. Taped it to PVC put 6 feet in air nothing.
This entire event is so counterproductive to what I know about radio and radio signals. I am pulling my hair out of my head. Took down LMR, RG-6 packed my stuff in my truck and called it a two day failure.
Any suggestions??
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Last edited by ecps92; 08-16-2017 at 8:00 AM..
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Old 08-16-2017, 6:32 AM
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Quote:
Originally Posted by Ubbe View Post
$10 variable attenuator
/Ubbe

Would you have a link to one? I would like to experiment with one. Preferable with type F coax connector.


Thanks
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Old 08-16-2017, 7:23 AM
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Quote:
Originally Posted by sdu219 View Post
I posted in the threat a RS-197. NOAA works fine as does conventional FM signal. For some reason I am missing something. Tried all new coax, Two kinds, two diff types of antennas for the band.
It works with the antenna physically laying on the ground in the crushed stone but not at 90 feet.
The two sites I picked are the closest sites that come in fine on the ground (literally)
It also works beautiful at 90 feet with a 6 foot section of LMR-400 sticking out of the radio connected to nothing at 90 feet. Puzzled !! I eliminated all the unknowns switched radios, antennas and coax
The only remaining possibility is signal overload. Your scanner is prone to receiver desense when it gets a strong input signal. If you get a S9+ signal just by connecting coax with no antenna, you have a very strong signal input. Connecting a Yagi pointed at that signal source is going to send an extremely high signal to the receiver, and it's no wonder it has trouble handling it.
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Old 08-16-2017, 9:19 AM
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If it a Radio Shack PRO-197, signal overload is a known problem. The radios have an attenuator button (ATT) that may help.

chris
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Old 08-16-2017, 9:51 AM
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In addition to what Bill said, a couple of other things.

You said you are using two Yagi antennas. If you connecting them both to the scanner at the same time, how are you doing that? If you're just using a "T" connector or are you using a signal combiner of some sort.

FWIW, I'm using a RS800 antenna on my 436HP and receiving Zone 3, Zone 5, and Zone 8 in my house near the Stoughton/Brockton/Easton line. I can't imagine why you would need anything more than a decent outside omnidirectional antenna unless you want to listen to something in Rhode Island. I'm even getting the 700Mhz overlay system from the Blue Hills site.



Quote:
Originally Posted by ecps92 View Post
So... with everything connected and raised, Nothing.
Take down and lay on ground and all is fine ? Great Reception ?

Might just be a grounding issue or a shorted cable/connection

BTW, from Brockton, for Zone 3 point toward Norwell vs Middleboro

However a Yagi for the Analog Simulcast sounds like over-kill
Reception of Zone 3 and Zone 5 have generally not been a reported issue
on Omni's or experiencing the P25 Simulcast issues
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Old 08-16-2017, 11:14 AM
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Quote:
Originally Posted by dave3825 View Post
Would you have a link to one? I would like to experiment with one. Preferable with type F coax connector.Thanks
There're both F types and IEC standard tv connectors available. Search on Ebay or Amazon for "variable attenuator" and you could also add "F connector" to the search. They should be available in local shops that sell sat/tv equipment.

/Ubbe
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