coax question?

[kc9neq]

i am going to install a scanner antenna on the roof of my residence. what type of coax should i use? the antenna's connector accepts a pl-259.

 

[RevGary]

Distance from scanner to antenna and your budget are important factors to consider. Let us know what that distance is and what your scanning interests are regarding antenna type and miles to the furthest agency that you will be receiving... then perhaps we can come up with a couple of suggestions that will fit your needs and available cash.

As an FYI, we are using RG213 on a 92 foot run to a 7 element VHF (only) beam and we can receive a 280 watt ERP agency transmitter 114 miles away. That was impossible using RG58U or RG8X... tried them both...

 

[freqs]

Distance from scanner to antenna and your budget are important factors to consider. Let us know what that distance is and what your scanning interests are regarding antenna type and miles to the furthest agency that you will be receiving... then perhaps we can come up with a couple of suggestions that will fit your needs and available cash.

As an FYI, we are using RG213 on a 92 foot run to a 7 element VHF (only) beam and we can receive a 280 watt ERP agency transmitter 114 miles away. That was impossible using RG58U or RG8X... tried them both...

is the rg 212 better than lmr 400 i run the rg 6 the fat stuff radio shop told me was the best but i feel its poor in rception and it is belden i han better lucck with rg 58 ??????

 

[RevGary]

Try this link below for a general comparison of related cables and their groupings. Look for the db loss per 100 ft. column as a general gauge of performance. If you had a transmitter as well, several other spec's might also be of use. RG212 has 1 db more loss per 100 ft than RG213 and are both 50 ohm impedance (Z) cables. RG6 is 75 ohm cable but your scanner may have an input impedance (Z) range, listed in the specifications page of your manual, that will accomodate that. Check the spec's that came with both your scanner and the antenna for their recommendations regarding impedance (Z). Hope this one helps you sort out things...

http://www.rfcafe.com/references/electrical/coax_chart.htm

 

[kc9neq]

will be using a bearcat 996t scanner, radio shack model 20-176 vhf-uhf 108-1300mhz antenna with a pl-259 connector. antenna coax run will be around 45 ft from scanner to antenna. antenna will be located on roof of residence with large portion of coax inside attic. will be listen mainly to 155-161 range, some 400 and 800 range. would like to hear around 30 to 40 miles away. more is alway better.

 

[SCPD]

Factor in that the higher the frequency the greater the loss on a given length of cable.
You may not notice much difference between two types of cable in the 151-162 range, but would notice far greater differences when trying to receive 400 to 800 MHz signals.

I use LMR-400 and like its durabiity as my roof can be covered with several feet of snow six months per year. I'm using a Diamond antenna with an integrated pre-amp (no longer available) which is omindirectional and I pull in VHF high transmitters in the 100 watt range which are 80-110 miles away with a 13,000 foot mountain range in between. I used some Belden 9913, which at the time had the lowest loss, and may still have the lowest loss for "flexible" cable, but the connectors were difficult to put on and I had a tough time bending it around corners.

 

[SCPD]

Oops, double post!

 

[kb2vxa]

Hi nmize and all,

For 800MHz you need the very "best" you can get, no doubt. That would be hard line but unless you can scrounge a spool end from your cable TV company it'll cost you some bucks. Next in line is Times Microwave LMR-800 but that's a bit pricey too. With LMR the 800 is the lowest loss and that goes up as the numbers go down. The best bang for the buck is Belden 9913 air dielectric coax but beware of imitations, there is ONE air dielectric (hollow) cable in the 9913 line so you have to look at it before you buy it.

Since the higher you go in frequency the more loss there is in any given cable it is all important you don't skimp on quality. The same goes for line length, the longer it becomes the more loss you have, Scrooges are losers.

 

[N9JIG]

i am going to install a scanner antenna on the roof of my residence. what type of coax should i use? the antenna's connector accepts a pl-259.

There are a lot of choices. At the top end is bulky coax types such as Beldin 9913 or even lower loss hard lines. You are talking several dollars a foot and big bucks for connectors, plus it is a pain to work with.

Next down the line is LMR400 and SuperFlex. You use regular RG-8 connectors, and the loss figures are decent plus they are easier to work with. Still kind of expensive though.

The cheap and easy route is a pre-made length of RG-8 or even RG-58 with PL-259's on both ends, and a PL-259 to BNC adaptor at the radio. Probably would work OK under 100 feet with RG-8 or under 50 feet for RG-58, but not as well as the better choices.

As an alternative you could use a good quality RG-6. Various sources have adapters that will bring the F-Connectors to the PL-259 needed on the antenna end and BNC at the radio.

I use 50 foot lengths of quad shield RG-6 with pre-installed F-Connectors on many of my scanner antennas and they work great. I have 3 of those RS multi-element scanner antennas that are equipped with F-Connectors on the balun, so I only need a single adaptor on the radio end. I tried a comparison of this coax with a similar length of 9913 (with an N-F adaptor on the antenna end and a PL-259-BNC on the radio end) and the RG-6 worked better on 800, 900 and UHF. I could not tell the difference on VHF or low band.

I then compared the Quad Shield RG-6 with 50 foot lengths of RG-8 (Beldin) and a couple RG-58 sets (Both a Beldin with ends I soldered on and a RS pre-made) and had similar results except the RG-58 was slightly worse than the others.

I then tried tests with all of the above coax's using a discone with an N-Connector, meaning each coax except the 9913 had an adaptor at the antenna and the results were exactly the same. The best coax was the Quad Shield RG6 by far.

The RG-6 Quad Shield coax from Radio Shack (Marks as "For Satellite TV Use") works fantastic for scanners. Even using an adapter at each end won't hurt.

There are some that say that since RG-6 is 75 ohm and the others are 50 ohm that the RG-6 won't work with a scanner. This is only important if you ever want to transmit thru the antenna (Maybe you have a discone that you might connect to a 2M rig for example). If it is dedicated to a receiver then 75 ohm cable is fine, even preferable in some freq ranges.

Since the antenna is outside the weatherproofing of the connection may end up being more important than the coax used. Do a good job with this and you won't have to replace it every year. The RS Quad Shield assemblies have rubber boots on one end, be sure this end goes outside. If you use other cables be sure to protect the outside ends.

 

[brwkem]

Looking at RS quad shield cable which one:

25-Ft. QuadShield Video Hookup Coax Cable (Black)
http://www.radioshack.com/product/i...058&kwCatId=2032058&kw=rg-6&parentPage=search

or

50-Ft. Outdoor QuadShield Coax Cable (White)
http://www.radioshack.com/product/i...058&kw=rg-6&kwCatId=2032058&parentPage=search

Are the gold connectors necessary or can you go with say Phillips RG6 Quad?
http://www.walmart.com/catalog/prod...ct_id=3904682&sourceid=0100000030660804302498

Use this for wall feed?
Wall Feedthrough Bushings for RG-6 (2-Pack)
http://www.radioshack.com/product/i...ategoryId=2032058&support=support&tab=support

thx

 

[fuzzymoto]

I'm not sure it is the BEST I can do but I have the same antenna (20-176) on a 10-foot mast on the roof. I have a Uniden scanner. Most of what I listen to is 150-160 with some 450-470 and very little 800Mhz. I have a run of about 50-feet of former sattelite TV RG-6 coax (F-connectors) and all of the associated adapters to connect it to the antenna, grounding block and scanner and it does very well. Perhaps a shorter run of LMR-400 with fewer adapters (no grounding block in-line) would do better but for my receive only use I'm not sure it's worth the expense. I'm sure one day I'll try it just to see if coax makes that much difference.

 

[N_Jay]

I'm not sure it is the BEST I can do but I have the same antenna (20-176) on a 10-foot mast on the roof. I have a Uniden scanner. Most of what I listen to is 150-160 with some 450-470 and very little 800Mhz. I have a run of about 50-feet of former sattelite TV RG-6 coax (F-connectors) and all of the associated adapters to connect it to the antenna, grounding block and scanner and it does very well. Perhaps a shorter run of LMR-400 with fewer adapters (no grounding block in-line) would do better but for my receive only use I'm not sure it's worth the expense. I'm sure one day I'll try it just to see if coax makes that much difference.

You don't need to do an experiment, just do that math!

 

[fuzzymoto]

I agree with the math. I'm just not sure the math translates to a real-world situation that will make an appreciable difference in what I listen to. I'm sure I'll try it at some point to satisfy my curiosity. I'm not completely convinced in the end the work and $$ would be worth it for me. If/when I build a new antenna/coax setup I'll certainly do it.

 

[N_Jay]

I agree with the math. I'm just not sure the math translates to a real-world situation that will make an appreciable difference in what I listen to. I'm sure I'll try it at some point to satisfy my curiosity. I'm not completely convinced in the end the work and $$ would be worth it for me. If/when I build a new antenna/coax setup I'll certainly do it.

I you can do some experiments if you want, but I would bet you can not tell a 3 dB or smaller change on an FM receiver.

 

[fuzzymoto]

I you can do some experiments if you want, but I would bet you can not tell a 3 dB or smaller change on an FM receiver.

I agree. That's my point. I can make my car 3 HP faster but I'm not sure I'd feel it in the seat of my pants or see it on a stopwatch.

If I do a new install I'd probably do LMR400. I doubt I'd convert my current install. ..

Although I am still curious.

 

[N_Jay]

I agree. That's my point. I can make my car 3 HP faster but I'm not sure I'd feel it in the seat of my pants or see it on a stopwatch.

If I do a new install I'd probably do LMR400. I doubt I'd convert my current install. ..

Although I am still curious.

Unless you screw up (no pun intended) a connector, I bet the "real world" loss will be within +/- 0.2 dB of the math.

 

[brwkem]

Is it wise to use a wall plate with F connectors installed then use a jumper from the plate to the scanner?

thx.

 

[N_Jay]

Is it wise to use a wall plate with F connectors installed then use a jumper from the plate to the scanner?

thx.

Well it looks nice and won't hurt anything.

 

[fuzzymoto]

Well it looks nice and won't hurt anything.

I tend to agree except that it seems that the general concensus on RR is that each connector, adapter or patch cable potentially diminishes your signal by some amount. As I've said above whether that "amount" is noticeable in the real work on the freqs. you monitor is certainly up for debate.

From my antenna I have F-type > 10-feet RG-6 > F-type > grounding block > F-type > 50-feet RG-6 > F-type > F-type to BNC adapter > Right angle BNC > BNC to SMA adapter > scanner.

Now would I be better with LMR400 with connectors on both ends to match my antenna & scanner? (F-type > LMR 400 > SMA)

Would I notice it in 150-160Mhz? 450-470Mhz? 800Mhz?

This seems to be the debate I see constantly. I guess on higher freqs it matter more and if something I want to hear is on the fringe then maybe...but in general will it really matter?

 

[N_Jay]

I tend to agree except that it seems that the general concensus on RR is that each connector, adapter or patch cable potentially diminishes your signal by some amount. As I've said above whether that "amount" is noticeable in the real work on the freqs. you monitor is certainly up for debate.

From my antenna I have F-type > 10-feet RG-6 > F-type > grounding block > F-type > 50-feet RG-6 > F-type > F-type to BNC adapter > Right angle BNC > BNC to SMA adapter > scanner.

Now would I be better with LMR400 with connectors on both ends to match my antenna & scanner? (F-type > LMR 400 > SMA)

Would I notice it in 150-160Mhz? 450-470Mhz? 800Mhz?

This seems to be the debate I see constantly. I guess on higher freqs it matter more and if something I want to hear is on the fringe then maybe...but in general will it really matter?

If the connectors are done well you will never notice the difference on a scanner.

Figure 0.1 or 0.2 dB per connector and you need 3db to notice, and typically 6 to be an issue.