Help with splicing RG58A/U Coax

Status
Not open for further replies.

Jmoore06

CheapRig
Premium Subscriber
Joined
May 6, 2020
Messages
16
I erected my mast and new antenna, but I am having a heck of a time trying to ground the RG-58 coax with conntecters to the antenna block.

The antenna came with RG58-au coax and I had to shorten the length. I purchased a compression conntector kit but have had no luck getting the f connectors to attach to the coax. I also purchased the only crimp style conntectors they sold at Home Depot (twist on and crimp style for RG-59 but they will not hold on the RG-58 coax.) I just need to connect a female style connector to the coax to attach to the grounding block, and then attach another connector to the whip I made that has a BNC connector on the other end. I have been unable to find any RG-58 specific connectors at any stores in my area. The RG-58 also doesn't have a sold wire but rather stands of aluminum wire, how will I connect that wire into the grounding block that without fraying all the strands when I twist it together? Any help would be great!
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,674
Location
SNCZCA01DS0
The antenna came with RG58-au coax and I had to shorten the length. I purchased a compression conntector kit but have had no luck getting the f connectors to attach to the coax.
Right. Those connectors are either for RG-59 or RG-6 and are not going to work.

I also purchased the only crimp style conntectors they sold at Home Depot (twist on and crimp style for RG-59 but they will not hold on the RG-58 coax.)
And the stranded center conductor isn't going to work in an F connector in any reliable way.

I just need to connect a female style connector to the coax to attach to the grounding block,
Which type of grounding block do you have? Does it have F style connectors on it?

and then attach another connector to the whip I made that has a BNC connector on the other end. I have been unable to find any RG-58 specific connectors at any stores in my area. The RG-58 also doesn't have a sold wire but rather stands of aluminum wire, how will I connect that wire into the grounding block that without fraying all the strands when I twist it together? Any help would be great!
You've got a mix of cable and connector styles that are not going to lend themselves easily to what you want to do. You could chase connectors, crimpers and the such all day long and all you are going to do is spend a lot of money and waste a bunch of time.

If the grounding block has F connectors, here's what I'd recommend:
Get rid of the RG-58
Go to the hardware store and get enough RG-6 to go from the antenna to the radio.
Sounds like you already have the compression type F connectors and tool, so make sure you have the right ones for the RG-6, if not, buy a couple.
Last time I was in Home Depot, they also had RG-6 BNC compression connectors. But a few of those, also.

Put a BNC connector to match your antenna on the RG-6 coax. Run that coax down to where the cable enters your home. Cut the RG-6. Install a compression type F connector on the end. Attach that to the grounding block. Mount the grounding block to the exterior wall. Run a ground wire down to your ground rod, and don't forget that the National Electric Code requires that ground rod to be bonded to your home ground rod.
Put a compression F connector on another length of coax. Attach that to the other side of the grounding block. Run the coaxial cable into your home and to your radio. Install one of the BNC compression connectors on the end of that cable. Attach to your radio.
Now, go back and properly weather seal the outdoor BNC connector at the antenna. While you are at it, weather seal the exterior F connectors also.
Connect to your scanner, enjoy not having the headache from trying to use mismatched cables and connectors.
 

iMONITOR

Member
Premium Subscriber
Joined
Sep 20, 2006
Messages
8,818
You don't want to use RG58 coax, or PL-259 connectors if this is for a scanner radio.
 

Jmoore06

CheapRig
Premium Subscriber
Joined
May 6, 2020
Messages
16
Thanks all for the info!

The RG-58A/U came with the antenna. It actually works pretty good for my application, but I am fine with replacing the coax and getting something better quality. I will move forward with the RG-6...But please advise if there are different types of RG-6 coax. My RG58-A/U is 50 ohm?

I have a few BNC connectors that work with the RG-58A/U. Can I use them with the RG-6 coax?

How much better quality is the RG-6 than the RG-58A/U?
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,674
Location
SNCZCA01DS0
Thanks all for the info!

The RG-58A/U came with the antenna. It actually works pretty good for my application, but I am fine with replacing the coax and getting something better quality. I will move forward with the RG-6...But please advise if there are different types of RG-6 coax. My RG58-A/U is 50 ohm?
RG-6 is 75Ω cable.
Your RG-58 is 50Ω cable.

Yes, there will be a bit of additional loss due to the impedance mismatch, however over a long run, the RG-6 has significantly less loss than RG-58.

I have a few BNC connectors that work with the RG-58A/U. Can I use them with the RG-6 coax?
No, they are not going to work. Get the correct ones for the RG-6. It's a few bucks and will save you a lot of money on Tylenol and putting money in the 'swear jar'.

How much better quality is the RG-6 than the RG-58A/U?
RG-6 has less loss. How much better depends on the exact version of RG-58, how long your cable run is, and what frequencies you are listening to.
 

Jmoore06

CheapRig
Premium Subscriber
Joined
May 6, 2020
Messages
16
Thanks again for the help with this. On the way to Home Depot to get the RG-6 now. Lot's of great info in these forums.
 

ArloG

Member
Joined
Feb 14, 2020
Messages
117
You stated your original cable is RG-58
That means your antenna and cable are 50 ohm impedance.
Now you're planning to change your cable to RG-6. It's 75 ohm.
There are 50 & 75 ohm F connectors. There IS a difference.
You also state that your present setup "Works pretty good".
Now you want to introduce an impedance mismatch of cable and antenna to a radio that is "probably" designed for a 50 ohm impedance input.
Many say it won't matter, and in an area of very strong signals....it might not.
But that setup will not be right. And Home Depot will not have 50 ohm cable or connectors because they're a home-depot.
Not a ham radio supply house. Which is where you really should go to to get everything you need to make a correct installation.
Quality correct cable, connectors, a lightning/static block. That's what you really need.
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,674
Location
SNCZCA01DS0
In a perfect world with a good budget, absolutely. RG-58 isn't helping, and trying to mash together connectors to make it work with the parts you have is going to be difficult. The 'right' solution would be to use a lightning suppressor designed for 50Ω cable and standard 50Ω connectors.
even with all that, a long run of RG-58 isn't doing him any favors. It may have worked, but it can work a whole lot better with minimal investment.

It's a hobby, and doing the best they can with limited budgets is just reality. Chasing fractions of a Decibel gets expensive with minimal payback. Sure, there's additional loss with the 50Ω/75Ω impedance difference, but unless it's a band specific antenna, the impedance is going to be different.

Again, perfect world, 50 feet of LMR-400, N connectors, Polyphaser, etc. That's the way to go.
 

ArloG

Member
Joined
Feb 14, 2020
Messages
117
In a perfect world with a good budget, absolutely. RG-58 isn't helping, and trying to mash together connectors to make it work with the parts you have is going to be difficult. The 'right' solution would be to use a lightning suppressor designed for 50Ω cable and standard 50Ω connectors.
even with all that, a long run of RG-58 isn't doing him any favors. It may have worked, but it can work a whole lot better with minimal investment.

It's a hobby, and doing the best they can with limited budgets is just reality. Chasing fractions of a Decibel gets expensive with minimal payback. Sure, there's additional loss with the 50Ω/75Ω impedance difference, but unless it's a band specific antenna, the impedance is going to be different.

Again, perfect world, 50 feet of LMR-400, N connectors, Polyphaser, etc. That's the way to go.
I could almost agree. Looks like the only problem here is a correct 50 ohm F connector.
I'd almost slap a few in a padded envelope and send them out.
I just moved an antenna and swapped the 6+ year old 9913 for LMR-400. A buck a foot. Another antenna has 9913 flex off of the same spool that is 6+ years old. Same N Type connectors. Talk about your bang for the buck.
The thing is with the scanner guys is they rx only. If you're going out to HD to buy a spool of 75 ohm thinking it looks the same as 50 ohm and works the same in a RF saturated area. It just may work OK. I live in a VHF/UHF sparse area, so every last microvolt counts.
Of course a good SWR on the way out is mandatory too.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,514
Location
Stockholm, Sweden
If there's anyone here that has a VNA analyzer then analyze your scanners antenna port and then analyze the antenna over the frequency ranges you use it for and note the impedance values you get.

You'll then notice that perfect impedance match of the coax will have little or no influence of the total result.

The mismatch between 50 ohm and 75 ohm are a 0,2dB loss.
If you have mismatch between 50 ohm and 100 ohm you'll end up with a SWR of 2:1 and if the whole coax attenuates 4dB the SWR will make an additional loss of 0,4dB and give a total of 4,4dB coax loss.


/Ubbe
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,674
Location
SNCZCA01DS0
And if you compare RG-58 to RG-6 losses, you'll see that RG-58 has quite a bit more than 0.2dB of loss at UHF at anything over a few feet long.
If you try to install incorrect connectors, losses will go up.

And while there are 50Ω F connectors, they would need to be ordered, you won't find them at a Home Depot, Lowes, Ace or anywhere else. Then you need the proper crimp tool, and if you don't have one of those, you'd be looking at $40 bucks for a decent/cheap one.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,514
Location
Stockholm, Sweden
You can get the twist on type of F connector that uses the RG6's own center lead as the pin and don't need any expensive tools to get the job done. There's 4, or maybe even more, different sizes of connectors to suit the different outher diameter of RG6 coax. They are marked by 1-2-3 number of rings on the connector, or no ring. It's vital to get the proper size as they otherwise will come loose. It should take quite an effort to screw them on. I can't pull any connector off its coax how hard I try. They should sit that tight on the cable. Whenever you switch the coax to a different lenght you only twist off the connector and reuse it. It helps getting the braid and foil cut to the perfect dimension using a special $5 cutting tool that have several razor blades that cut the outher insulation, the braid&foil, and the inner insulation.

If you already have the coax or order from another place than the connectors, then cut of a small piece of coax and take with you to a place that sells connectors and try the different sizes they have. You should be able to twist on the connector on the outher plastic insulation and not be able to just pull it off.

/Ubbe
 

Jmoore06

CheapRig
Premium Subscriber
Joined
May 6, 2020
Messages
16
Comet 150-DS Discone Antenna. Roof mounted at 25 feet off the ground with 50 feet of coax. Will be using it for general scanning applications. R-6 Quad shield coax is what I purchased. Thoughts?
 

gtaman

Member
Joined
Oct 23, 2010
Messages
880
Location
GALAXY 19 91.0° W
RG6 quad will work fine or tri shield. Best connectors are Beldon Snap N seal or PPC EX ones. Strip the cable. Fold the braid down and slide the connector on make sure the dialectic is flush with the bottom of the threaded ring. Cut the stinger flush with the top of the connector. Make sure you actually compress the connector. Don’t over compress it. Your tool may have a built in stop.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,551
Location
So Cal - Richardson, TX - Tewksbury, MA
I think a run of LMR-400 would have been in order with an N female at the radio end and a short flexible jumper to the radio. I use RG-6 on my TV antenna and for my DirecTV runs, but not for scanner antennas. Regular satellite rated RG-6 is fine, no need for quad shield in most cases. It will work for your scanner antenna and you will hear stuff, but there are more "correct" ways of doing things.

To me its like you want to put some nice wheels on your car so you get new rims and they are 8" wide. Then you stick on some cheap tires that are only 6 1/2" wide and the side walls taper outward at an angle to reach the rims. I know you all have seen this. Yea you can drive on it. No, its not right.

Comet 150-DS Discone Antenna. Roof mounted at 25 feet off the ground with 50 feet of coax. Will be using it for general scanning applications. R-6 Quad shield coax is what I purchased. Thoughts?
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,514
Location
Stockholm, Sweden
It's more like you have 4x4 and you put on the best low profile road tyres you can get but you only drive on gravel and in the terrain. You pay too much for something that are not neccesary. Scanner antennas and scanners are not expensive 2-way radios and antennas that have a perfect 50 ohm impedance at the frequency they are used for. If RG6 coax and connectors are good enough to be used with sat dish signals at 3GHz then it's probably good enough for scanner use.

Spend your money on a low-noise amplifier, it will isolate the impedance from the antenna to the coax and with a lower noise level it will increase the scanners sensitivity and also make the coax a non attenuating device, a win-win situation. Always use a variable attenuator to adjust for best possible signal quality in the scanner as little too much signal will instead make the scanner loose it's sensitivity.

/Ubbe
 
Status
Not open for further replies.
Top