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Best coax to use

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eng645

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#1
I have a Pro-106 and only listen to 700 - 800mhz P25, I'll need to run aprox. 50' of cable. I'm looking for middle of the road as far as pricing. Here are antenna specs.

Gain: 6 dBi SWR: 1.5:1 or Less on Center Freq Pattern: Omni-directional
Wavelength: Multiple 1/2 Tuned: 769-775 MHz Band: 700 MHz Safety
Connector: N Female Cable: RG8X Cable Length: 24 Inches
Height: 57" Width: 1 1/4" Weight: 1 lb 11
 

cpetraglia

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#2
That sounds like a nice commercial co-linear antenna. If you want to get the most out of it, I would use nothing less than LMR400. It costs more, but anything lesser will be wasting gain from that nice antenna. Be sure to seal all outdoor connections and get it as high as you can !!
 
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Point Nemo.
#3
I agree, LMR-400 would be the MINIMUM I'd use. LMR-400 is not the holy grail of coax cable, it's mediocre, but better than most of the consumer stuff you'll find.
50 feet of LMR-400 will result in about 1/3 of the received signal being lost at 800MHz. Not bad, not ideal, might be "good enough" depending on how strong the signal is that you are trying to receive.

RG-11 would be a bit cheaper and will lose a bit more signal, but cost less. It is a 75Ω cable, but it'll work fine for receiving. Issue you may have is finding the correct N connectors for it. Ideally you want to avoid adapters, especially outside.

LMR-600 would probably be what I'd run, in fact I did use it for a 35 foot run to a discone at my house. It's more rigid than either of the two above, but it'll only lose about 1/4 of the signal over a 50 foot run. Easier to find N connectors for. LMR-600 is pretty stiff, so don't have any wild ideas about routing this inside a wall easily. I can be done, but it's going to take some work.
Losses for LMR-600 are only slightly more than what you'd get with 1/2" heliax (LDF4-50A). Heliax is really good stuff, but overkill for hobby use.

At work I've got an 800MHz repeater with a 40 foot run of cable and I'm using 7/8" heliax (LDF5-50A) and that's considered appropriate for that sort of install. Cables like Heliax are not realistic for most hobby users as it's stiff and has a large bend radius, so not easily run in a residential environment.

Really it comes down to what your budget is. Asking for the "best" can mean a lot to different people depending on how much they are willing to spend. "Best" can meet a lot of things to different people.

Often RG-6 is recommended, and while it will work, it's cheap and it's readily available, it's pretty easy to do better unless your budget is really tight.
RG-8 would not be recommended as it's going to lose over half your signal in the cable run.

Most important thing to look at is that none of this is going to make a difference if you don't install it correctly. If you don't have experience doing coax terminations or have the correct tools, you might want to consider buying your cable pre-terminated. This can save some headaches.
Try not to use adapters if at all possible. Adapters will add some loss, but more importantly they can be fragile and create failure points, especially outdoors and in locations you can't get to easily to replace. Ideally make all your connectors match. Since your antenna has a female N connector, you'll want a male N connector on one end of your cable. That way you can directly connect your antenna pigtail directly to the coax.
At the indoor end, don't try to connect heavy cable like these directly to your radio. Since it's heavy and stiff, it's really easy to break the antenna connector off your radio if you do. Industry usually terminates the coax near the radio, then uses a small flexible jumper to make the final connection to your radio. This can be RG-58 if it's kept short (a few feet). While it'll have some loss, it's pretty small and not noticeable. LMR-195, LMR-200, LMR-240 will all work well, too.

Waterproofing your outdoor connections needs to be done carefully. No point in doing all this work if you don't and water intrusion wrecks your cable. Wrap the connections with electrical tape, follow that up with moldable mastic tape designed for coax sealing. Follow that up with another pass of "half lapped and back" electrical tape. Done right, it'll last for years.

And... Don't forget proper grounding and lightning protection.
 

Ubbe

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#4
As RG6 are used in every tv/radio installations all over the world it has an unbeatable cost/performance value. It's a 6dB attenuation compared to LMR400 4dB. The RG6 twist on connectors are almost impossible to do wrong. Buy a ready made pig tail cable for the antenna and scanner with the proper connectors.

Concider using an amplifier at that frequency and cable lenght. Using an amplifier with an internal noise level of 1dB (a $20 cost) will only loose that 1dB between antenna and scanner. There's absolutly no reason going with a more expensive cable when you only want to use it one way for receive.

/Ubbe
 
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#6
I would suggest Ultra Linear Low Noise Amplifier PGA-103 10MHz - 2GHz LNA Gain 20dB; NF 0.5 dB | eBay or Ultra Low Noise Amplifier 10 - 3000 MHz Gain 20dB NF=0.65 dB with ESD + Bias Tee | eBay and add a 10uH coil to be able to power it from the coax. At the scanner you use a power inserter, either a cheap one to power an active TV antenna with 5volt or MicroUSB Bias-T | eBay or Bias Tee Operates from 10MHz to 7000MHz; Bias-tee; Bias-T w/ DC hdr or USB power | eBay

Put the amplifier in a box like this DiSEqc Water Proof Case - Fit Any 4x1 DiSEqc Switch - Free Shipping | eBay

Your scanner might get swamped and overloads of the strong signals so concider using antennas direct variable attenuator | eBay and possible FM Notch Filter 88-108MHz for SDR; Excellent Rejection 85dB; Bandstop; 9th order | eBay

You will also need adapters or pig tails to connect everyting together.

/Ubbe
 

K845rp

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somewhere in MICH/Ohio/SouithBend,Indiana
#7
Canada

We love our neighbors to the North,

but as I notice your in the USA,

I would suggest using the titles and finding a USA seller of the same Filter, (stuff) noted (as all the links are from Canada and might incur customs duties....

Sure are many USA sellers with the exact same stuff(or better yet DIY and you learn)!

Cheers,
SM
 
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