Attic Mounted Yagi

[Volfirefighter]

I am having trouble receiving a distant 800 Mhz P25 system. How well would a professional grade yagi work mounted in the attic. Roof mounting is not an option. I would have a short run of LMR 400 to the scanner.

 

[doctordialtone]

How well would a professional grade yagi work mounted in the attic. Roof mounting is not an option.

It depends a lot on construction materials, obstructions, transmitter power and the distance to the transmitter.

Inside 25 - 30 miles might work OK.

 

[popnokick]

Take a handheld portable scanner.... or your tabletop scanner if you must... up into the attic. Try to receive the 800 mHz P25 system you're interested in. If you get ANY of it... even weakly or broken up.... the Yagi will work to improve the signal. But what if you don't hear anything with the handheld or tabletop scanner? Go back up again, but this time with the Yagi and adapter that allows it to connect to the antenna jack on your radio. Point the Yagi in the direction of the P25 signal.... and see if you pick up any of it. If it works, mount the antenna in the attic where the signal is best. Locate "best" place to mount it by moving the antenna around (and radio if necessary).

 

[abqscan]

I would say as long as the roof isn't metal, or, have any type of foil backed material, I would say yes.

My home has asphalt shingles and I have placed multiple yagis in my attic feeding radios with RG-6. Some yagis are fixed, and two of them are on rotators. I'm using a couple of RCA rotors from Amazon that have a memory feature. If I want to monitor a different site, I push a button and the antenna points to the direction programmed into the preset. As for my antennas, I'm using one commercial yagi and a couple of cheap ones I found on ebay and they all work great.

https://www.amazon.com/AUDIOVOX-Rem...rds=rca+rotor&qid=1559699210&s=gateway&sr=8-1

Like popnokick said, increase your elevation and try a yagi to see if this resolves your reception issue. I would try on top of the roof first, and, if it helps, then try the attic. If the yagi continues to help, finish the install.

 

[iMONITOR]

PM sent

 

[Volfirefighter]

Thinking of going with this yagi:

https://www.theantennafarm.com/catalog/browning-br-6383-3584

Any recommendations on where to purchase a good quality 25' piece of LMR400 with N Male on both ends. I am seeing them for about $60 on Amazon and $50 at The Antenna Farm.

Also, ant difference between LMR400 and Belden 9913?

 

[Joe_Blough]

Thinking of going with this yagi:

https://www.theantennafarm.com/catalog/browning-br-6383-3584

I realize I am a few weeks late to this thread but that's a 6db gain yagi. You can get a 5 element 8db gain yagi for about $11, a 7 element 11db gain yagi for about $13 and a 9 element 13db gain for about $16 shipped free from AliExpress.

I bought this one that covers 806 to 960 MHz for $15.60 which comes with an F connector (most come with an N connector) so is perfect for RG6 coax with F connectors. Also comes with the mounting hardware. I received it on 10 days, despite a projected time of 21 days. I have it indoors mounted on a 5 foott long piece of 1.5 inch ID PVC pipe and it works great. Had a system that could not pick up and this allows me to receive it fine.

5 element 8db yagi
7 element 11db yagi

 

[iMONITOR]

I realize I am a few weeks late to this thread but that's a 6db gain yagi. You can get a 5 element 8db gain yagi for about $11, a 7 element 11db gain yagi for about $13 and a 9 element 13db gain for about $16 shipped free from AliExpress.

I bought this one that covers 806 to 960 MHz for $15.60 which comes with an F connector (most come with an N connector) so is perfect for RG6 coax with F connectors. Also comes with the mounting hardware. I received it on 10 days, despite a projected time of 21 days. I have it indoors mounted on a 5 foott long piece of 1.5 inch ID PVC pipe and it works great. Had a system that could not pick up and this allows me to receive it fine.

5 element 8db yagi
7 element 11db yagi

A lot of the digital public service communications are entering the 700+ MHz spectrum. Is your yagi working ok for those (if you have them)?

 

[mmckenna]

Thinking of going with this yagi:

https://www.theantennafarm.com/catalog/browning-br-6383-3584

Browning/Tram are the BaoFeng's of the antenna world. Cheap, flimsy but they'll work OK as long as you don't expect too much of them. In an attic where they won't be subjected to wind/rain/weather, they may be OK, but you can -easily- do better. CCA, Cheap Chinese Antenna...

As said, 6dB isn't a lot of gain. A 3 element Yagi gives you a bit of directionality, but not really a whole lot. If what/who you are trying to listen to is all in one direction, then a higher gain antenna would be a better choice.

Any recommendations on where to purchase a good quality 25' piece of LMR400 with N Male on both ends. I am seeing them for about $60 on Amazon and $50 at The Antenna Farm.

Also, ant difference between LMR400 and Belden 9913?

At 50 feet, you likely will not notice a difference between 9913 and LMR400. The fractions of a decibel cannot be heard on a hobby grade receiver. Chasing 0.x dB of signal gets expensive and won't result in enough difference in the signal strength to be noticeable.

50 feet of LMR-400 at 850MHz is going to have about 1.8dB of loss. That means about 65% of the signal received by the antenna will make it to the end of the cable. Not an issue for a good receiver with a strong enough signal.
50 feet of Belden 9913 at 850MHz is going to have about 2dB of loss, or about 63% of the signal received by the antenna will make it to the end of the cable.
So, 2% difference.

That is based on using —real— cable, not cheap Chinese knock off stuff. Do not spend your hard earned dollars on "LMR-400 Equivalent", "As good as LMR-400", Etc. The most expense in installing coax cable is your labor and your safety.

If you are going to put the labor into it, do it right and get name brand cable.

Antenna Farm is a good source, I've used them for small orders that are under the minimum numbers for the larger companies I use.

Hooking all this up...
LMR-400 is a little stiff, so you do not want to connect it directly to your radio, it risks damaging the antenna connector on your radio by putting too much strain on it. Industry standard is to use a short whip of smaller cable as a jumper to make the final connection.
I'd recommend getting your LMR-400 with Male N connector on each end. Attaching one end to the antenna directly will be OK if it's in the attic and you provide proper strain relief. On your radio end, get a short jumper of RG-58 with a Female N connector on one end and a suitable connector on the other to connect to your radio.

 

[Ubbe]

If money is an object then satellite dish CATV cable RG6 have 2.8dB loss. It's much easier to correctly fit connectors yourself to a RG6 coax but adapters are needed but the coax are thin and easy to route. If performance are important then an amplifier will help a lot at the antenna and coax quality becomes secondary. 50ft of LRM400 costs almost the same as RG6 , a good amplifer and a 10dB attenuator.
RG6 Coax Coaxial F type Cable HD Satellite Cord TV Antenna CL2 Black LOT | eBay
Ultra LNA 2GHz Gain>20dB PGA103 ESD Gain Stabilization USB cable PGA-103 NF .5dB | eBay
Eagle 10 dB Attenuator Pad Inline DC Block Female Male F-Type 75 Ohm In-Line | eBay

/Ubbe

 

[Joe_Blough]

A lot of the digital public service communications are entering the 700+ MHz spectrum. Is your yagi working ok for those (if you have them)?

The one I got is rated for 806 to 960 Mhz and I am using mine mainly for a trunked system at 935 Mhz which I couldn't pick up at all before getting the antenna, which is mounted inside at the back of my house pointing out a window opposite the direction of the transmitting antenna. I also use it for an 853 MHz system but that one comes in fine on just a small telescoping antenna.

I don't have 700 Mhz systems but have also used this yagi on 450 Mhz frequecies and it picks them up but I did not do any comparison tests to see if it is better or worse than the telescoping dipole antenna I used before it since I don't listen to much on 450 Mhz.

 

[Volfirefighter]

Thanks for all the advice in this thread and the one about pointing the yagi. I went with a Browning 6386 9dB gain, 25 ft. of LMR400, and a short pigtail to the scanner. I mounted in a 2nd floor closet next to my shack as the attic would have only gained me a cople more feet of elevation and the attic was well over a hundred degrees this weekend. Went from 1 to 2 bars of signal and missing transmissions to 5 full bars and great reception.

 

[Volfirefighter]

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[JoshuaHufford]

Glad to hear you are getting such good results.

 

[Frankhappyg]

Good to hear
Best thing I did was ditching the discone putting up a Wilson Yagi 301111 & replacing RG6 low loss coax with Altelix 400.


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