Home-made Stub Antenna

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Twister_2

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I have a unique problem with my Pro-106. We have a simulcasted P25 system and I can only decode the system at a level that a normal human being can understand but 5% of the time. I only have two good places in my house to have the scanner to be even able to get the audio to come through. Everywhere else in the house it just gives me a unintelligible syllable here and there. I don't live far from any of the tower sites. In fact I could hear towers over 30 more miles away with 100% clarity. Its sounds just like the good old analog systems. I believe that my problem is multi-path. I've tried the attenuator but that does not work.

I don't want to use a directional antenna because I bought the 106 in hopes of keeping it portable. I also don't want to try different antennas because they are not cheap enough to try it and conclude that it does not work.

I've been thinking about building a antenna that intentionally makes the signals weaker. I want to build a stubby antenna. Before I do this, I want to see what you guys think. Does it have any chance at working? Do you think my problem is multi-path?

I live in Dauphin County. The system is here: Dauphin County Public Safety Trunking System, Steelton, Pennsylvania - Scanner Frequencies

Thanks
 

Twister_2

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I tried that. It might be helping but it's tough to tell. It's not like what it should be. Is there another cause that I'm overlooking?
 

fineshot1

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If you have too much multipath signal as you say then its probably time to
invest in an external bnc attenuator of perhaps 6 or 10db(not sure how much
your internal attenuator is worth) and if necessary kick in the internal atten
if that is not enough but first you should confirm it is too much multipath
before making the expenditure. Your best way to confirm multipath may be
to borrow someones yagi and point it at different sites and see if that helps
out with the garble problem.


BNC Fixed Attenuators - RF, Cables, Video Cables, RF Parts, Connectors
 

Alliance01TX

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Stubby Antenna - Attenuation

As the prior post recommends the attenuation of the Signal Level is one good step and likely the best one.... As I do-not know the radio you are using, I would also try another radio and see if you are getting the same result in the same location(s) inside your home. Just to ensure you get consistent results.

Is the P25 traffic the only issue you are having, or do have other freq's that are-not clear? The reason I am asking is to re-establish if it is only one (1) frequency range, etc...and not other interference from a PC, fluorescent lights or other electro-mechanical devices...etc...

Also, re-check you Radio Shack Manual as I think (not positive) this scanner my have a built-in Attenuator that is Menu selectable?

Hope this helps....

Thx

Bill
 

Twister_2

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As the prior post recommends the attenuation of the Signal Level is one good step and likely the best one.... As I do-not know the radio you are using, I would also try another radio and see if you are getting the same result in the same location(s) inside your home. Just to ensure you get consistent results.

Is the P25 traffic the only issue you are having, or do have other freq's that are-not clear? The reason I am asking is to re-establish if it is only one (1) frequency range, etc...and not other interference from a PC, fluorescent lights or other electro-mechanical devices...etc...

Also, re-check you Radio Shack Manual as I think (not positive) this scanner my have a built-in Attenuator that is Menu selectable?

Hope this helps....

Thx

Bill
I can monitor the York system with no problems. That's quite a distance away. York County PA Public Safety Trunking System, York, Pennsylvania - Scanner Frequencies

The one I can't monitor is the one that covers my area. Dauphin County Public Safety Trunking System, Steelton, Pennsylvania - Scanner Frequencies

They are both 500 MHz, so I don't think my problem is interference.
 

ramal121

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I would definitely say you are having multipath problems. Since attenuation doesn't seem to help much, my guess is the offset and direct signals are pretty much the same in level. A directional antenna would be the best way to go.

A down and dirty way to get some directional capabilities is to mount a quarter wave whip inside a coffee can (practical for uhf and up). Swing it around and see how it works. If there is no improvement, you're out very little money and only some of your time.

Another thing to try is body shielding. Hold the scanner close to your chest. During a transmission, face different directions. Maybe the reflected signal can be attenuated through your body to where the audio picks up a bit. This would indicate a directional antenna would help.
 
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jim202

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As this is not a simulcast system, I have to ask which site control channel are you listening to?

You need to pick the closest site and it's control channels and not worry about any other site.
my guess is that your putting in more than one site to have the scanner trunk on. It isn't
going to work that way.

Jim




I have a unique problem with my Pro-106. We have a simulcasted P25 system and I can only decode the system at a level that a normal human being can understand but 5% of the time. I only have two good places in my house to have the scanner to be even able to get the audio to come through. Everywhere else in the house it just gives me a unintelligible syllable here and there. I don't live far from any of the tower sites. In fact I could hear towers over 30 more miles away with 100% clarity. Its sounds just like the good old analog systems. I believe that my problem is multi-path. I've tried the attenuator but that does not work.

I don't want to use a directional antenna because I bought the 106 in hopes of keeping it portable. I also don't want to try different antennas because they are not cheap enough to try it and conclude that it does not work.

I've been thinking about building a antenna that intentionally makes the signals weaker. I want to build a stubby antenna. Before I do this, I want to see what you guys think. Does it have any chance at working? Do you think my problem is multi-path?

I live in Dauphin County. The system is here: Dauphin County Public Safety Trunking System, Steelton, Pennsylvania - Scanner Frequencies

Thanks
 

Twister_2

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As this is not a simulcast system, I have to ask which site control channel are you listening to?

You need to pick the closest site and it's control channels and not worry about any other site.
my guess is that your putting in more than one site to have the scanner trunk on. It isn't
going to work that way.

Jim
Well I only listen to the Simulcast portion. That is the part that covers my area. (Dauphin Co is a large county)

All simulcast sites operate on the the same frequencies (obviously lol) and the same CC's, I believe, according to the database.
 
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