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Coax to Feed a Yagi

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johnp3205

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I am putting up a new 800 mhz yagi. I will need 75ft of coax to feed it to my shack. What is a good quality, cost effective, low loss coax for this feed? Thanks,
John
KB8YTB
 
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kb0nly

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RG6 Quad Shield would be a good cheap choice for receive only. Other than that LMR400 or better but the cost is a lot higher! I fed my 800Mhz scanner antenna with 1/2" hardline, yeah wasn't cheap but maximized my efforts!
 

Skypilot007

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Medford, NJ
I've had good results with belden 9913 and a 75ft run on 800MHz. I run it into an active multicoupler for use with multiple receivers. Works good.
 
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kb0nly

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I've had good results with belden 9913 and a 75ft run on 800MHz. I run it into an active multicoupler for use with multiple receivers. Works good.
Nothing wrong with 9913... Just be SURE you seal it up good at the connections, otherwise your air core coax turns into a water pipe... LOL
 

LtDoc

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It's a fairly good idea to use a feed line of an impedance that will be compatible with both the antenna and the antenna. Of course, having a low level of loss is also nice. Best way I can think of to determine which coax would be best for your particular circumstances is to take a look at a 'loss' table and select the feed line that best satisfies your requirements -and- wallet.
And then there's the 'practical' side of things, as in putting on the proper connectors etc. Cable that uses aluminum shielding is a PITA to work with for most people, it's hard to solder to. And just how flexible is that cable? Can you make the required bends and thread the stuff where it has to go? A compromise here and there, if properly chosen, isn't all that terrible, you know?
- 'Doc
 
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kb0nly

Guest
It's a fairly good idea to use a feed line of an impedance that will be compatible with both the antenna and the antenna. Of course, having a low level of loss is also nice. Best way I can think of to determine which coax would be best for your particular circumstances is to take a look at a 'loss' table and select the feed line that best satisfies your requirements -and- wallet.
And then there's the 'practical' side of things, as in putting on the proper connectors etc. Cable that uses aluminum shielding is a PITA to work with for most people, it's hard to solder to. And just how flexible is that cable? Can you make the required bends and thread the stuff where it has to go? A compromise here and there, if properly chosen, isn't all that terrible, you know?
- 'Doc
All good points... However, many scanner antenna's have F connectors on them anyway, if not you can convert easily with adapters. There is even compression fit BNC connectors for RG6 that go on as quick and easy as an F connector.

The impedance difference is not a big deal for receive only applications. I know hams using RG6 for HF receive antenna feeds as well.
 

Rsmims

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Feb 27, 2010
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Southern Utah
Lmr 400

if i was you id go get http://www.timesmicrowave.com/products/lmr/downloads/22-25.pdf

by far best cable I've had and very low loss as others stated above you cant beat it
Disclaimer:
The following is strictly my opinion, and is based on my personal experience. It is offered without any warranty. It is strictly MY opinion and does NOT have to be yours or anyone elses. I don't have a PHD in antennas, I just know what works for me. Your results may vary based on your application.

I use a 75' run of 50 ohm LMR400 into 2-6 port splitters that feeds 11 of my scanners, 7 of which are online here. This low loss cable is great. A night and day difference over the RG8X that I started out with. (And YES, you CAN get 75 ohm LMR400, but don't)

I cannot stress this enough: Keep everything 50 ohm. The scanners are 50 ohm impedance, so make sure your antenna, cable, and any switches, splitters, etc., are all 50 ohm as well. This will make a difference on that "distant fringe agency signal" you are trying to "hear". Impedance match matters, even on receive only. Impedance mismatch WILL cause signal loss.

Also, make sure your antenna resonates within the bandwidth that you want to monitor. Don't expect that low cost 2 meter antenna, tuned to 145 mhz to pick up an 800 mhz signal. Antennas MUST be tuned to a center frequency that is within the range of the signal you want to receive. I use 2 discones here.
They cover from 30 Mhz up to 1.3 Ghz and everything between. As your using a Yagi, you should already know this, but some who may read this may not.

Here are the links to the cable and the splitters that I use:

Cable - http://usacoax.com

Splitters - see ebay item # 200525450921

Hope this helps and good monitoring....
 
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