Stubby antennas

[bearcatrp]

Has anyone tried a stubby antenna for P25 to help reduce simulcast signals that crush some scanners? Already have a 150 but the 160 I have suffers pretty bad in my area for P25. Have around 10 simulcast towers around me. I have a stubby antenna but wrong connector and not sure what frequencies it covers. In my radio parts bin. Could get an adapter but don’t want to waste money if it doesn’t help.

 

[wtp]

here is a start,

Simulcast Distortion - The RadioReference Wiki

wiki.radioreference.com

i had limited progress with a 1 and a half inch stubby,
but everyone is in a unique position.
even moving your radio an inch or two can change reception.
you have to find a sweet spot, if you have one.
some have even used paper clips.
and when out and around, it was a little hit or miss.
we did get the SDS100 and it works like any radio should, all the time.

 

[Enforcer52]

Build you own:

1/16th Wave Length 700-800 mhz Antenna For Non-Simulcast Scanners

1/16th Wave Length 700-800 mhz Antenna For Non-Simulcast Scanners While visiting my son in Fort Worth and helping a friend in Florida program his BCD325P2 in a Heavy Simulcast area with some problems, I took the time to do some research with my own BCD325P2 versus my SDS200 on the Tarrant...

forums.radioreference.com

 

[sonm10]

Correct me if I'm wrong, but the 160 is not meant to be receive simulcast. The 150 absolutely is for receiving simulcast. Two different scanners with two different functions.

 

[K4EET]

Hi @bearcatrp, you could try a paperclip 📎 on your Uniden BCD160DN to see if that makes any difference. Try different lengths too. The shorter the better in many cases. Also, don’t forget about the built-in software attenuator on your scanner. That could help. Like has already been said, moving the scanner a few inches to find the “sweet spot” might improve things too. Another trick to try is by changing the antenna polarization from vertical to horizontal (lay your scanner on its back).

In my case with the Uniden BCD536HP, I have achieved decent reception in a heavily simulcast environment by reducing the antenna gain by 20dB or so 😂 and finding that sweet spot. I simply use inline attenuation that can be easily removed when I want to receive non-simulcast systems.

If you don’t have any inline attenuators with BNC type connectors on-hand, some examples would be:

Amazon.com

Inline Attenuators | DXE HAM Radio Equipment

Find Inline Attenuators and get Free Shipping on Most Orders Over $99 at DX Engineering!

www.dxengineering.com

ATT-20 Variable Attenuator | Scanner Master

ATT-20 Variable Attenuator

www.scannermaster.com

It is always fun to experiment with different methods in an attempt to overcome simulcast distortion…

<edit>

I just noticed that the Amazon link is NOT a set of attenuators (pictured) as I originally thought. It is for a single 20dB attenuator. Having a set of different values is helpful for experimentation. There are other attenuators on Amazon for $15 each. Shop around…

 

[RobDLG]

Already have a 150 but the 160 I have suffers pretty bad in my area for P25.

To be clear, 150 and 160 refer to these? smileyantenna.com

 

[bearcatrp]

Thats for 145-155 Mhz. Am looking for one that covers 700-900 Mhz. Saw a few online but going to try the other suggestion using a paper clip just for giggles to see what happens.

 

[GettingOld]

Thats for 145-155 Mhz. Am looking for one that covers 700-900 Mhz. Saw a few online but going to try the other suggestion using a paper clip just for giggles to see what happens.

That VHF antenna would most likely work better than a 700-900 MHz tuned antenna. You want to attenuate, not amplify.

 

[GettingOld]

Has anyone tried a stubby antenna for P25 to help reduce simulcast signals that crush some scanners? Already have a 150 but the 160 I have suffers pretty bad in my area for P25. Have around 10 simulcast towers around me. I have a stubby antenna but wrong connector and not sure what frequencies it covers. In my radio parts bin. Could get an adapter but don’t want to waste money if it doesn’t help.

My problem isn't with a full simulcast system, it is with a simulcast site. The only two things that work is finding that sweet spot and/or changing the antenna from vertical to horizontal positions.

 

[RobDLG]

Am looking for one that covers 700-900 Mhz

Avoid the Diamond RH3. When used with my BCD325P2, its performance is comparable to the stock antenna, so it's not what you're looking for.

I also tested the Gabil GRA-SCH32, which had noticeably lesser performance than the RH3, and costs under $20, but I'm guessing a paperclip is a better option at this point.

 

[bearcatrp]

Tried the paperclip this morning. Same as with antenna. My next option is to program my local frequencies to see how it does.

 

[K4EET]

Tried the paperclip this morning. Same as with antenna. My next option is to program my local frequencies to see how it does.

Does the Uniden BCD160DN have a numerical RSSI on the display? Or on your Uniden SDS150, what is the received signal level at that particular location? For the stock antenna and the paper clip to be the same, the received signals must be fairly strong. That is where attenuation is needed to knock down the received signals to the point that the scanner will “lock” onto the stronger signal of the bunch so the Uniden BCD160DN scanner has a chance to decode from a single site, if possible.

You may want to spend $13 to $20 for one set of following attenuators to see what knocking the signal down will do. Knowing what your numerical RSSI is at your location will help in determining just how much attenuation might need to be inserted to reduce the signal levels while keeping the strongest signal above the noise floor. Since Uniden does not publish specs for receiver sensitivity, we will have to make a WAG and start around -100dBm.

Let me know if you have any questions.

Amazon.com: BECEN 2pieces 2Watt SMA 15dB Attenuator, DC-6GHz,50 Ohm，Precision Adjustable Signal Loss for RF Systems, Testing, Broadcast & Communication : Electronics

Amazon.com: BECEN 2pieces 2Watt SMA 15dB Attenuator, DC-6GHz,50 Ohm，Precision Adjustable Signal Loss for RF Systems, Testing, Broadcast & Communication : Electronics

a.co

Pair of 15dB attenuators for about $13

https://a.co/d/05EERJcM

Pair of 20dB attenuators for about $20

https://a.co/d/04BYxAg2

Pair of 30dB attenuators for about $20

NOTE: This is a test only and may or may not work depending on your received signal strengths.

 

[bearcatrp]

Most of my signals are at max receive strength.

 

[Enforcer52]

How long was the paperclip you tried from the top of the antenna connector?

It should only have been about a straight 7/8 of an inch.

You definitely need to cut down the signal if you are getting full bars reception.

 

[K4EET]

Most of my signals are at max receive strength.

What is the Uniden SDS150 showing for RSSI in dBm for the simulcast system being discussed? I think that scanner can display that value in dBm.