Any Cable Experts Out There?

[cassidy1190]

Hey I am looking for a certail type of coaxil cable. RG8 or RG6. I am trying to pick up state police(trunked, type II, 800MHz) and I am in a fringe area. I was told that these 2 cables would be the best. I just want to know can I get either one with BNC on both ends, I really dont want to soldier anylthing, and I can't stand the signal loss I get with all the converters. A 12 ft cable or longer would be nice.

 

[N_Jay]

Hey I am looking for a certail type of coaxil cable. RG8 or RG6. I am trying to pick up state police(trunked, type II, 800MHz) and I am in a fringe area. I was told that these 2 cables would be the best. I just want to know can I get either one with BNC on both ends, I really dont want to soldier anylthing, and I can't stand the signal loss I get with all the converters. A 12 ft cable or longer would be nice.

If you only need 12 feet then the type of cable is not very critical (as long as you stay away from the RG-58 size stuff.

I would go with RG-6 and F to BNC adapters.

I would guess getting RG-6 with F connectors should be no trouble at all.

 

[cassidy1190]

wow thats funny, I have RG-58. and its spliced to anouther RG-58 in the middle. lol..better rethink my setup thanks for pointing this out. :lol:

 

[Dubbin]

Didn't we just go through all this in another thread :roll:

 

[cassidy1190]

yeah I figured since that thread was originaly for the preamp not to clot that one up with all this cable stuff. sorry if I caused any truble.

 

[Voyager]

Hey I am looking for a certail type of coaxil cable. RG8 or RG6. I am trying to pick up state police(trunked, type II, 800MHz) and I am in a fringe area. I was told that these 2 cables would be the best. I just want to know can I get either one with BNC on both ends, I really dont want to soldier anylthing, and I can't stand the signal loss I get with all the converters. A 12 ft cable or longer would be nice.

RG-58 loss is 15 dB per hundred feet. Since you're running about 12 feet, you will only have about 1.5 dB loss. You will NEVER see a gain even going from 1.5 dB loss to 0 dB loss, so don't worry about the RG-58. If you want to improve it, run a single piece without the splice. You're likely losing more in that connection than the entire cable.

If you want to upgrade, go to RG-8, NOT RG-6. Stay with 50 ohm cable. That will cut your losses in half plus, but again, you will never hear the 0.8 dB net gain for just 12 feet.

If you want to really get fancy, run 1/2" Heliax. 0.2 dB loss for your length run, but again, you're never going to see/hear the 1.3 dB net gain over RG-58.

Again, the best thing you can do is replace the two pieces with one. And it's a lot easier putting BNCs on RG-58 than anything else mentioned. Try to not use any adapters, and for 800 MHz, DON'T USE UHF CONNECTORS! That will kill your signal.

Joe M.

 

[N_Jay]

Hey I am looking for a certail type of coaxil cable. RG8 or RG6. I am trying to pick up state police(trunked, type II, 800MHz) and I am in a fringe area. I was told that these 2 cables would be the best. I just want to know can I get either one with BNC on both ends, I really dont want to soldier anylthing, and I can't stand the signal loss I get with all the converters. A 12 ft cable or longer would be nice.

RG-58 loss is 15 dB per hundred feet. Since you're running about 12 feet, you will only have about 1.5 dB loss. You will NEVER see a gain even going from 1.5 dB loss to 0 dB loss, so don't worry about the RG-58. If you want to improve it, run a single piece without the splice. You're likely losing more in that connection than the entire cable.

If you want to upgrade, go to RG-8, NOT RG-6. Stay with 50 ohm cable. That will cut your losses in half plus, but again, you will never hear the 0.8 dB net gain for just 12 feet.

If you want to really get fancy, run 1/2" Heliax. 0.2 dB loss for your length run, but again, you're never going to see/hear the 1.3 dB net gain over RG-58.

Again, the best thing you can do is replace the two pieces with one. And it's a lot easier putting BNCs on RG-58 than anything else mentioned. Try to not use any adapters, and for 800 MHz, DON'T USE UHF CONNECTORS! That will kill your signal.

Joe M.

You will not lose 1/2 your signal due to the mismatch, however it is better to be matched (all 50 ohm).

RG-8 is a high power cable not a high frequency cable.
RG-6 is a high frequency low power cable.

 

[cassidy1190]

well here's what I did. I moved stuff around, put the scanner on a high shelf, and now I am only using one 6ft cable erather than two 6 ft cables. If I am correct that is onyl a loss of 0.16 dB. I can tell too. My 800Mhz and all my other frequencies for that matter come in better. I am really getting all I can out of my discone now without all the dB loss.

 

[Voyager]

well here's what I did. I moved stuff around, put the scanner on a high shelf, and now I am only using one 6ft cable erather than two 6 ft cables. If I am correct that is onyl a loss of 0.16 dB. I can tell too. My 800Mhz and all my other frequencies for that matter come in better. I am really getting all I can out of my discone now without all the dB loss.

6' of RG-58 will have half the loss of 12 feet. So, you are seeing about 0.75 dB loss, not 0.16 dB. If you noticed a big difference going from 12 to 6 feet, it's most likely due to the splice. Otherwise, it's due to a bad cable. Again, UHF connectors, if used, kill at 800 MHz. I had one on my mobile antenna and when I changed it to a BNC, I noticed an improvement. That's how bad they are. Yes, the UHF connector was fine. It's just that a BNC connector doesn't have the impedance problem that UHF connectors have. (note: impedance issues - as in RG-6 vs RG-8 )

Not NJ, I didn't say going from RG-6 to RG-8 would cut the loss in half - I said that going from RG-58 to RG-8 would cut the loss in half. But, at these small lengths, it won't matter.

As for the difference between RG-6 and RG-8, the only real difference is impedance. RG-6 is 75 ohm and RG-8 is 50 ohm cable. In all other aspects they are similar. The ratio of inner conductor to outer conductor is slightly different, but that's how you get the impedance difference. For radio, 50 ohm cable is a standard. 75 ohm cable is used for TV or cable line, where the equipment is designed for 75 ohm cable. (and 75 ohm connectors such as 'F' connectors)

Power and frequency are inversely proportional in ANY cable. You can run higher power at a lower frequency in any coaxial cable, and must run lower power at a higher frequency. Exceed the cable spec of power vs frequency and you get a boom and spark, and you replace the cable.

Joe M.