coax advice

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gfdfortynine

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This weekend I am hopefully installing a Cushcraft AR2 antenna for my scanner (weather permitting) and I am looking for some advice on cabling.
My choices.
I have a roll of 8x that will cost me $1.50 a foot
A roll of RG58 (Thinnet coax) free from work
Or go buy some RG6

I will be receiving only, 150MHz the run about 50'

Thanks
 

n5ims

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This weekend I am hopefully installing a Cushcraft AR2 antenna for my scanner (weather permitting) and I am looking for some advice on cabling.
My choices.
I have a roll of 8x that will cost me $1.50 a foot
A roll of RG58 (Thinnet coax) free from work
Or go buy some RG6

I will be receiving only, 150MHz the run about 50'

Thanks
Let's simply run the numbers and see how they look.

Common factors, 150 MHz frequency and 50' run for a receive-only application (based on your post):
* RG-58 - 2.552 dB loss
* RG-8x - 2.146 dB loss
* RG-6 - 1.729 dB loss

Since lower loss is generally better, looks like the RG-6 is the winner for your application!

Other things to factor in:
* Thinnet coax is designed for indoor use so it probably won't last too long outside with the UV rays eating up the outside jacket in just a few years. Connectors should be easy to find and rather inexpensive, however most aren't water tight so you'll need to protect them with some good quality (and UV resistant) electrical tape and "Coax-Seal" putty-like material (Using Coax-Seal).
* RG-8x is generally made for outside use so it should be OK for several years use. It was designed for HF use, not VHF so it really isn't that great of a performer at 150 MHz. The connectors are similar to RG-58 (but may use a different reducer since 8x is a bit larger than 58).
* RG-6 is easy to find, cheap, and very low loss. It's also generally well shielded so there is less leakage (in or out) so it works well near other cables. The connectors are cheap and can be quite good (even water tight), but it's hard to find anything but "F" or "BNC" for RG-6. Adapters aren't too hard to find to convert F or BNC to most anything else you want, however (adapters may not be water tight though so seal them up!).

Be aware that RG-6 is 75 ohm cable, while the others are 50 ohm cables, but for receive-only applications it shouldn't be an issue. If you transmit, none of the 3 types are good choices so don't worry about the impedence until then anyway.
 
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K9WG

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I second the RG-6. Get a good grade satellite coax and the 50/75 mismatch will present a much smaller loss then the loss from RG-8 or RG-58.

If you transmit, none of the 3 types are good choices so don't worry about the impedence until then anyway.
I 100% disagree, I have used RG-6 from 160 meters to 450Mhz with very good results. The impedance mismatch loss is more then offset by the low loss of the coax and the 100% shielding is well worth it.
 

JASII

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Coaxial Cable

Even though you are only concerned now with 150 mHz, you might be interested in higher frequencies or amateur radio in the future, so you might even take a look at 9913, or better, feedline.
 

LtDoc

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One choice that wasn't mentioned is 'Times Microwave' LMR-400. It's designed for VHF/UHF use. I don't have the loss figures handy but they should be at least as good as RG-6. Considering the price quoted for RG-8X, the LMR-400 would be cheaper, at least from the one dealer I use ($.89/foot, +S&H about~ $1.10/foot shipped).
About impedance. Why -make- a mismatch when it isn't necessary? It won't make much difference when you are only listening, but that 'much' is relative and will contribute to the total losses of any system.
- 'Doc
 

gfdfortynine

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I was looking for that nudge to use the RG6

The 8x was higher priced because I got it from a local marina on the quick. One of the electricians I work with used to be into ham radio and he kept saying 50Ω but he of course was into transmitting. He said we used to have miles of the cable, must be a roll some where. I come across the thinnet cable and thought I won the free cable lotto. But reading the posts here got me wondering if the 58 was up to the task and then also noticed the 8x wasn't much better.

Thanks for the advice and if I ever decide to transmit I have a good pull wire for the better cable ;)
 

K9WG

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... snip ...About impedance. Why -make- a mismatch when it isn't necessary? It won't make much difference when you are only listening, but that 'much' is relative and will contribute to the total losses of any system.
- 'Doc
For me it was about economy. When I can get 50-feet of RG-6 for $15 at my local WalMart I'll put up with the mismach (only 0.177dB of loss). Especially with a 10db gain antenna.
 

mpddigital

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Walmart RG-6 is pretty bad. Chinese crap at it's best. YMMV

$1.50 a foot for 8x is Highway Robbery. We have sold it as low as .35 per foot for US Made Alpha. If you want to use 75 Ohm look at RG-11 you can get it for .35 cents a foot and that is for US Made Times cable. LMR-195, LMR-200, LMR-240 and LMR-400 are all much less than what you paid for the 8x. If you like braided copper then look at good RG-213. 214 is way overkill. Be careful with
9913, Belden makes good cable but there has been a ton of fake copies on the market so know your seller.

For 150Mhz you can do a 100 ft run for not much cash. If you are going to 800Mhz or higher look for RG-11 or good microwave coax to limit loss.
 

LtDoc

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K9WG,
I think you might recalculate the loss factore for RG-6. 0.177 for 50 feet? Sorry, I don't think so.
- 'Doc
 

kb2vxa

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There will be no impedance mismatch if you remember this. Length of the vertical element determines resonant frequency, the position of the rod on the ring determines feed point impedance. If you want to set it up correctly borrow an antenna analyzer and someone who knows how to use it.
 

ipfd320

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wow here we go again all this input on coax..like other threads posted on the site there is alot of confusion...its amazing that i use regular cctv coax cable split into 9 scanners and all recieve just fine from 33.00 meg to 1200.00 meg all off a tv antenne on the roof
 

prcguy

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In my opinion the best and correct coax to use of all mentioned in this thread is LMR400. Its 50ohm, real low loss @ 150MHz and not that expensive at under a buck per foot retail. You can get 50ft lengths with your choice of connectors installed on Ebay for very reasonable prices.
 

HOLEBILLY

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I just replaced RG6 coax with lmr 400 coax and all I can say is wow.What a difference that made on all freqs received. Im now pulling in 800mhz that I did not even know was with in my range. I did not know that useing lmr 400 would make such a difference or I would have done that long ago. The best inprovement came on 800mhz but they all improved.
 

e737

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In my opinion the best and correct coax to use of all mentioned in this thread is LMR400. Its 50ohm, real low loss @ 150MHz and not that expensive at under a buck per foot retail. You can get 50ft lengths with your choice of connectors installed on Ebay for very reasonable prices.
This is the best advice you will get in this thread!
 

mpddigital

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There are good sellers on eBay, we sell there also. Just PLEASE read the fine print and make sure you Know what you are buying!

If the seller doesn't say it is Times Microwave LMR-400 it isn't we can buy the chinese stuff for 33 cents a foot in bulk. Some sellers are selling this as LMR when it is not.
 

thomasbillman1

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coax

how about LMR300 i paid 99 cents a foot and it sure makes a difference , very low loss. If you want the best for scanning this is what I would get . Its better all those listed here.
 
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