RG-6??

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radio3353

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Looking for opinions on using RG-6 with F-connectors for a receive only application. VHF/UHF/700-800 MHZ. Run would be ~50 feet. Thanks.
 

mmckenna

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Sure, it'll work.
TV stations up near the top end of the UHF band used to run up in the 800MHz range. It'll work better than RG-58, and most cheap RG-8's.

And, it's cheap!
 

n5ims

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You might find (or even make using crimp connectors) some RG-6 with BNC connectors. Be aware that those connectors will be the 75 ohm versions. While the impedance won't be an issue, the physical differences between the 75 and 50 ohm BNC connectors could cause issues. The main issue is that with the 75 ohm version, the center connector (or more specifically the material surrounding it) is a different size than that on the 50 ohm version. This may cause mating problems or even breaking of one or both connectors. To be safe, I placed a 50 ohm 90 degree adapter in between so if there was a problem, I'd just have to crimp on a new connector on the cable and/or trash the adapter. You may also have difficulty pushing the connector onto the radio (or other device) and if so, you may want to use extra care in making the connection since the difficulty is trying to tell you that something isn't right.
 

Ubbe

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It's the standard coax for satellite dishes that outputs 2GHz in the coax. It's a low loss coax and usually have multiple screens with foil that doesn't let any interference enter the coax when routed near electronic devices. They selected 75 ohm to be the optimum impedance for small signal systems. A receivers sensitivity are measured in voltage or dBm and with higher impedance the voltage are higher and the current are lower and the signal doesn't disappear in the noise floor as quickly as 50 ohm. F connectors are easy to install yourself even without any special tool but a $5 coax stripper are a good help. Make sure to get good quality adapters or use pigtails that often are of better quality at the same cost as adapters.

/Ubbe
 

spongella

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All the RG/6 I've used has aluminum braid but does it come in copper too? That would be helpful when soldering to home brew antennas.
 

Ubbe

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Copper are an expensive metal to use so most coaxes uses all aluminium with a aluminium centerlead covered with thin copper layer. RF only travels on the surface of metals so it doesn't matter to the performance if they used a solid copper lead.

You could probably wrap a naked wire several turns tight around the coax exposed aluminium braid and solder it and then use the end to solder to whatever you wanted to have contact with the braid.

/Ubbe
 

mikewazowski

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Knock yourself out. I use RG6 for scanning applications since it's cheap.

You can even toss on a cheap tv amplifier and splitter if you're feeding multiple scanners.
 

questnz

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Note, not all RG6 Coax are the same, get good quality Quad Shield type made is US of A, it should be ok for receive only application.
 

MisterLongwire

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Yeah. Like me. I don't think you know what the heck you are talking about Ubbe. I put 500w into my ham rigs using RG6 with no problems, from 80 to 10 meters. Wjere in the heck you get your info from? Better get acquainted with more book reading available from ARRL.
 

MisterLongwire

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After all, this is about receive only. Why get unnecessarily over-technical over something simple. RG6 is fine....so is RG8 for long lengths. Regardless of length involved no real noticeable loss. Learn simple answers so not to confuse the guy. Geez!
 

prcguy

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Quad shield is completely unnecessary for use with a scanner receive antenna. Its for use with tightly bundled runs of coax at L-band with different signals on different cables where you can't afford any cable cross talk. A satellite downlink spectrum in coax can cover 250Mhz to 2150MHz with up to about 80 signals at -25dBm each and simultaneously in the coax. At 1GHz and below and with typical off air receive levels this is not a problem for standard CATV type RG-6. I've measured all of this in a lab for the largest satellite company in the US and have probably installed more RG-6 than most people on RR.

My opinion on using RG-6 for scanner use with a 50 ohm rated antenna is, there is a right way with low loss 50 ohm coax and a compromised way using anything else. Personally, I don't like to compromise.


Note, not all RG6 Coax are the same, get good quality Quad Shield type made is US of A, it should be ok for receive only application.
 
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ab3a

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As you can see, there are many opinions about coaxial cable. What it boils down to is this:

How much are you willing to spend to hear more stuff? Some of this has to do with where you live. For example, in a city or close-in suburb, you probably don't need the low loss or the fancy stuff, so even cheesy "RG-58 Type" is often enough. (the "RG-58 type" is not really RG-58, but it kinda sorta acts like it at lower frequencies)

On the other hand, if you live in the sticks, with the nearest civilization being a hour's drive away on the highway, then you really should invest in good coax and good antennas, a decent size pole and so forth.

Good luck!
 
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