Will RG6/U 75 Ohm - CATV cable work??

[bigjstud1108]

I found a roll of RG/6U 75 ohm Coax cable used in CATV installation, I was wondering if I could use this cable for my set up. I currently have a RS 20-176 Outdoor VHF-Hi/UHF Scanner Antenna w/ 35 ft of RG-58.

 

[obijohn]

RG-6 works fine for scanner antenna's. Don't bother to replace your rg-58 coax, because in my experience, the difference in loss is negligible-unless you are listening to 800 MHz. Then you will improve the signal quality.

The difference between 50 ohm and 75 ohm coax is negligible as far as SWR. Don't get hung-up on that unless you plan to use the antenna to transmit on. Even then it doesn't matter most of the time.

 

[bigjstud1108]

Thanks alot, i do listen to the 800 mhz alot, every angency here in Pheonix, AZ is going to the 800 Mhz Digital

 

[W4KRR]

Thanks alot, i do listen to the 800 mhz alot, every angency here in Pheonix, AZ is going to the 800 Mhz Digital

I would replace the RG-58 with the RG-6, no question.

 

[K0ATC]

Thanks alot, i do listen to the 800 mhz alot, every angency here in Pheonix, AZ is going to the 800 Mhz Digital

If everything is 800, I would use LMR400 or an equivalent. You will notice quite a large gain going from 58. With 35ft of RG58 at 800mhz you get 4.7db of loss, that is well over half you signal, every 3db gain is a doubling of your signal. With 35ft of LMR400 at 800mhz you only get 1.3db of loss, so essentially you will be doubling your signal, or cutting your signal loss in half by switching to a lower loss coax. Now with signals that already come in clear, they will sound the same with the new coax, but for signals on the fringe or things you can not receive at all, you will notice the change.

Scott

 

[N_Jay]

A heard up for those not used to working with dB..
Yes, 3dB is 1/2 your signal, but 6 dB is only one "S unit", and is hardly noticeable in FM.

Don't let all the people focusing on "3dB is 1/2 your signal" scare you.

 

[K0ATC]

A heard up for those not used to working with dB..
Yes, 3dB is 1/2 your signal, but 6 dB is only one "S unit", and is hardly noticeable in FM.

Don't let all the people focusing on "3dB is 1/2 your signal" scare you.

Half is half, don't let your S meter fool you, as I stated, if the signal is clear already, it means nothing, if it is weak or border line, it will make all the difference. N_Jay is correct in saying 6db is the equivalent to 1 S-unit. What is not mentioned is most S meters are not liner, and good for nothing but a side by side comparison of signal strength at best. You calculate your gain and loss with the components you are using, such as coax, connectors, antenna, and so on. Once you change something let your ears decide if it is better, what may show up on your S-meter as 1 S-unit, could be as much as a 10db gain, or as little as 3db. If you do not have professional equipment, do the math and don't rely solely on your S-meter. You can find great information on calculating your gains and losses of your system from the ARRL handbook at www.arrl.org Coax and your antenna are the most important parts of your system, they can make a 100 dollar scanner sing, and a 3000 dollar receiver deaf.

Here is another way to explain it. Monitor some of the frequencies in your scanner, you should find some that do not even move your S-meter, though they are as clear as other frequencies you see full scale on your S-meter. The difference between those with no signal strength, and transmissions you can not hear could be as little or less then 1 S-unit, or 6db of gain you could have had if you had used better coax. It is a fact, if you have lossy coax, and transmissions that come in fuzzy with some static, upgrading your coax WILL make those signals come in perfectly clear 99% of the time.

I used a scantenna as an all around RX for my AR5000A, it came with 50ft of RG6. I had no other coax on hand at the time so I put it up to see how it did. When I bought a 50ft jumper of LMR600 and swapped it out, it was like the receiver came alive, I was off my yagi's more often, and could follow mobile simplex transmissions much farther before having to switch over to a directional antenna.

Bottom line, for all you with the new digital scanners, monitoring 7,8, and 900mhz systems, why spend 500 bucks on a nice scanner, and then try to save a few bucks on coax and degrade the capabilities of your receiver. Do your self a favor and give some good low loss coax a try, there are ton's of people on this board that have done it based on the recommendations of others, I dare you to find one that switched back, let alone did not say it was a noticeable difference.

Scott

 

[Uplink]

I use RG-6 (quad shield), works great. Sounds like you don't have a really long run, and an outdoor base antenna, so you should be OK. I agree, 800MHz does need low-loss cable, especially if your on the fringe. But as long as you are getting the repeaters solid now, and they are in range of you, you won't have a problem.