My Helium Mining Installation Part 3 – Preparing your coax and connectors

In part two of this residential Helium Mining Installation series we discussed the fiberglass push up mast that I used for this installation. In part three we will be going in depth on the coax used, RF connectors used, and RF adapters used. This includes the answers to questions like: “Which exact coax did I use?”, “Where did I get the coax from?”, “Which cable end connectors did I use?”, “How to install everything”, “How did I strip the coax ends to install the connectors?”, “How and why did I use a lightning arrestor?”, how to get this through you wall, and also what NOT to do and what to avoid. This will be all encompassing.

What coax should I use for Helium Mining?

I bought a spool of 500 feet of LMR-400 coax from The Wireman. A long standing and reputable source for coaxial cable. There are MANY reputable sources out there, but this happens to be where I got mine. I have multiple helium miner setups at all sorts of different locations and I got a spool as I have several runs to make that are at different lengths. I wanted to maximize my gain by reducing extra length by avoiding getting any “pre-made” jumpers, ensuring the coax does NOT droop. See the picture below:

LMR-400 coaxial cable for low loss coax runs for helium antennas - Max-Gain Systems, Inc.

What coaxial connectors and adapters should I use for Helium Mining?

I used the following:

5x Type N Male Crimp-on for LMR-400 coax

1x RP-SMA Male Crimp-on for LMR-400 coax

1x “PRO Version” 3 inch long, Type N female to Type N female bulkhead adapter

1x Type N male to Type N female right angle adapter

1x Lightning arrestor that works on 915Mhz with corresponding Type N Female to Type Female connectors

RF Adapters and RF connectors for helium mining install - Max-Gain Systems, Inc.

What tools did I use?

I used the following:

1x tape measure

1x utility knife

1x coax seal

1x black electrical tape

1x soldering iron

1x roll of solder (also sold in easy to use “tubes”)

1x ratcheting crimper and crimp die with .429 hex

1x large diagonal cutters

1x small (fine cutting) diagonal cutters

1x pliers

1x large vise grips (you can use just about anything to hold coax when you are soldering it that can give you an extra set of hands. The coax can get hot so you don’t want to being holding it.)

1x Standard Ohm Meter

Tools needed for helium mining install - Max-Gain Systems, Inc.

Measure your coax runs

Not only do you need to take the mast height into consideration, but you need to think about anywhere the coax needs to go. Along the roof, down the wall, and any turns in the coax. Any turns in the coax need to have a decent radius and never be bent at a 90 degree angle as this would cause damage to the coax. I measured from the top of the my mast, down my house to the ground then back up to where I installed my lightning arrestor. I measured a total of 48 feet and cut a piece of coax at 50 feet.

I then measured from where my lightning arrestor was to where my “bulkhead” adapter was going to be, which includes a little extra for large radius turns. This run would have 2 turns to make. I measured 4.25 feet and cut a piece of coax at 5 feet.

The last coax run is a short jumper from the indoors side of the “bulkhead” adapter to where my miner was going to sit. I wanted it to be hidden to not make my wife mad at me so I fit the miner in a fake plant =). I measured 1 foot and cut a coax piece at 1 foot.

Measuring coax run for helium antenna installation measurement from wall adapter to miner measurement - Max-Gain Systems, Inc.

Installing the Type N Male Crimp-On Connector

I am going to explain how to install a Type N male, Crimp-on connector on to LMR-400 coax below.

Coax Stripping

First cut your cable to the desired length and then strip the black jacket back approximately 0.54 inches. When the jacket is stripped cut the braid/foil back 0.23 inches from the fresh cut end. Finally, cut back the dielectric 0.12 inches from the fresh end down to the center conductor. The braid needs to be cut back further than the dielectric to insure that none of the braid or foil is touching the center conductor which could cause a short.

Note: Do not nick the braid, dielectric, and center conductor if at all possible. Tinning of the center conductor is not necessary if contact is to be crimped. For solder method, tin the center conductor if the center is stranded. twist the center conductor very tightly prior to tinning.

Install Method Selection:

Slide the outer ferrule onto the coax as shown below. Flare the braid slightly to allow insertion of the connector main body. Important: Do not comb out braid.

Place the center contact on the center conductor of the coax so that it butts against the cable dielectric. The center conductor should be visible through the solder / inspection hole of the contact.

Crimp or solder contact in place as follows:

Crimp-on Method Use the 7505-DIE-400 with a hex of 0.128 and 0.10 installed into a 7505-HANDLE Ratcheting crimp handle for the center pin. Start by using the large hex of 0.128 on the pin crimp location. depending on the coax being used, you may need to use the 0.10 hex in order make a secure connection. (DO NOT OVER CRIMP / CRUSH THE CENTER CONDUCTOR)

Solder-On Method Make sure the solder hole is facing up. Touch the soldering iron to the underside of the center pin directly under the solder hole. Touch the solder to the center conductor through the solder hole on the center pin. Allow the heat from the metal to melt the solder so that it wicks into the center pin. Once the solder melts it only takes a tiny amount of solder to make the connection. Do not allow the solder to pool over the solder hole. The outside of the center pin should be free of obstructions for insertion. Do not over heat the center pin which could cause swelling of the dielectric of the coax.

Type N male Crimp On for LMR-400, RG-213, RG-8 7305-N-400 installation guide drawings step 2 real world job - Max-Gain Systems Inc

Main Body Install:

Install the cable assembly with the center pin already affixed, into the main body of the connector. The knurled portion of the main body slides under the braid of the coax. Push the cable assembly into the main body until the center pin snaps into place in the dielectric of the connector.

Slide the ferrule (placed on the coax at the beginning of Step 2) over the braid and completely up against the connector body. Using the 0.429 hex of the 7505-DIE-400 installed into the 7505-HANDLE ratcheting crimp handle, crimp the ferrule at the location shown in the picture below (on the ferrule, but right up against the main body of the connector).

Type N male Crimp On for LMR-400, RG-213, RG-8 7305-N-400 installation guide drawings step 3 - Max-Gain Systems Inc

Final Testing:

When this is completed, as a final test, you should always check resistance from the center pin to the body with an ohmmeter in a low resistance scale. After verifying that there are no braid – to – center pin shorts on the other end of the coaxial cable, you should see infinite resistance (open).

Once the testing checks out, this connector is good to use. Repeat this on each end of coax where necessary. I had to use 5 for my setup.

Connector Install FAQ

1.) The center pin is not going onto the center conductor of my coax.

It could be one of two things. If you have a solid center conductor on your coax, be sure that the center conductor is round. When you cut the coax to length, a diagonal cutter cuts by applying tremendous force to a small surface area which can “flatten” the center conductor. Use your pliers to squish the center conductor back into a round shape and it should work. If you are using a coax with a stranded center conductor, when cutting the coax, this may have “squished” the strands of the center conductor which may have loosened the wrap of the center strands. You may need to squeeze the strands back together, with your pliers, while twisting the strands back to as tight of a wrap as possible to make the center conductor smaller in diameter. If this does not work, you can use your small diagonal cutters to cut off 3-4 strands of the exposed center conductor which immediately decrease the diameter of the wrap. Some people will cry foul of doing this, but once you solder it, who cares… Its all in one bundle, so… meh =) Ill be making helium and they wont.

2.) I melted the dielectric of my coax.

You definitely want to avoid this where possible. By applying the soldering iron under the point to be soldered, the heat will rise quickly heating the work area. You will want to have the solder on the work at the point at which to be soldered. Once the solder starts flowing, let just enough in to give a coating onto the center conductor and so that the solder pools and fulls the “hole” in the side of the center conductor. This will provide the best connection, stop the center pin from coming off, and making the center conductor only needing direct heat for a very short duration.

Installing the RP-SMA Male Crimp-On Connector

We will begin by installing the RP-SMA male crimp-on connector on a piece of coax. This process is the same for all the types of coaxial cable that fit this RP-SMA male  crimp-on connector. These connectors fit on a wide range of coax types, including: RG-11, RG-213, RG-213/U, RG-393, RG-393/U, RG-8, RG-8/U, RG-8A, RG-83, LMR-400, LMR-400 Ultraflex, Belden 7810A, Belden 8216, Belden 83269, Belden 83284, Belden 84316, and other 0.39 and 0.405 Inch OD Coax.

Identify all connector parts (3 Parts):

Each connector consists of one body assembly (plug), one rear ferrule (crimp sleeve), and one center pin (plug contact).

RP-SMA male Crimp On for RG-8, RG-11, RG-83, RG-213, RG-393, LMR-400, and other 0.405 Inch OD Coax 8895-RPSMA-400 v2 - Max-Gain Systems Inc

Coax Stripping:

First cut your cable to the desired length and then strip the black jacket back approximately 0.54 inches. When the jacket is stripped cut the braid/foil back 0.23 inches from the fresh cut end. Finally, cut back the dielectric 0.12 inches from the fresh end down to the center conductor. The braid needs to be cut back further than the dielectric to insure that none of the braid or foil is touching the center conductor which could cause a short.

Note: Do not nick the braid, dielectric, and center conductor if at all possible. Tinning of the center conductor is not necessary if contact is to be crimped. For solder method, tin the center conductor if the center is stranded. twist the center conductor very tightly prior to tinning.

RP-SMA Male Crimp Connector for RG-8, RG-11, RG-83, RG-213, RG-393, LMR-400, and other 0.390 and 0.405 Inch OD Coax 8895-RPSMA-400 installation guide drawing step 1 dimensions real world job - Max-Gain Systems Inc

Install Method Selection:

Slide the outer ferrule onto the coax as shown below. Flare the braid slightly to allow insertion of the connector main body. Important: Do not comb out braid.

Place the center contact on the center conductor of the coax so that it butts against the cable dielectric. The center conductor should be visible through the solder / inspection hole of the contact. Crimp or solder contact in place as follows:

Crimp-on Method

Use the 7505-DIE-400 with a hex of 0.128 and 0.10 installed into a 7505-HANDLE Ratcheting crimp handle for the center pin. Start by using the large hex of 0.128 on the pin crimp location. depending on the coax being used, you may need to use the 0.10 hex in order make a secure connection. (DO NOT OVER CRIMP / CRUSH THE CENTER CONDUCTOR)

Solder-On Method

Make sure the solder hole is facing up. Touch the soldering iron to the underside of the center pin directly under the solder hole. Touch the solder to the center conductor through the solder hole on the center pin. Allow the heat from the metal to melt the solder so that it wicks into the center pin. Once the solder melts it only takes a tiny amount of solder to make the connection. Do not allow the solder to pool over the solder hole. The outside of the center pin should be free of obstructions for insertion. Do not over heat the center pin which could cause swelling of the dielectric of the coax.

RP-SMA Male Crimp Connector for RG-8, RG-11, RG-83, RG-213, RG-393, LMR-400, and other 0.390 and 0.405 Inch OD Coax 8895-RPSMA-400 installation guide drawing step 2 real world job - Max-Gain Systems Inc

Main Body Install:

Install the cable assembly with the center pin already affixed, into the main body of the connector. The Install the cable assembly with the center pin already affixed, into the main body of the connector. The knurled portion of the main body slides under the braid of the coax. Push the cable assembly into the main body until the center pin snaps into place in the dielectric of the connector.

Slide the ferrule (placed on the coax at the beginning of Step 2) over the braid and completely up against the connector body. Using the 0.429 hex of the 7505-DIE-400 installed into the 7505-HANDLE ratcheting crimp handle, crimp the ferrule at the location shown in the picture below (on the ferrule, but right up against the main body of the connector).

RP-SMA Male Crimp Connector for RG-8, RG-11, RG-83, RG-213, RG-393, LMR-400, and other 0.390 and 0.405 Inch OD Coax 8895-RPSMA-400 installation guide drawing step 3 - Max-Gain Systems Inc

Final Testing:

When this is completed, as a final test, you should always check resistance from the center pin to the body with an ohmmeter in a low resistance scale. After verifying that there are no braid – to – center pin shorts on the other end of the coaxial cable, you should see infinite resistance (open). This completes your RP-SMA male crimp-on  connector installation, and the connector is ready for use!

Weather seal your connections

A good additional step to to use your coax seal to seal up the connection points where you only used crimping. See those pictures below:

Installing the “Bulkhead” or “Through-the Wall” adapter

You will need a 5/8 inch or 3/4 inch forstner drill bit for this this. Drill through the wall where you would like and install all of the parts of the Type N female to Type N female Bulkhead adapter. I used a 3 inch as I was going through 1.25 inches of material. You may need more or less length and we carry those ranging from 1.125 inches long up through 12 inches long.

Install your lightning arrestor

I used a metal bracket I had on hand, but you can use any 90 degree angle bracket for this. I installed this so that it was pointing up and down. Lightning always takes the shortest path to ground. I left enough coax so that it makes a U turn at the ground then go up into my arrestor. My arrestor is then attached by a 20 gauge copper wire down to an eight foot ground rod hammered into the ground.

I did all of this because the braid and jacket of coax is not going to stop lightning from bursting through and reaching the ground. This is my first line of defense against a strike, and the arrestor will get any residual surge that makes it through my loop to travel back up. Having multiple ways to negate lightning damage is always a good idea! If you can think of more, let me know!

Hook it all up!

At this point, all of the major items should be assembled and just need to be hooked up. You can do this all on your own or wait for Part 4. That is where I am going to go into how to hook all of this up, cable management, and general house keeping items that will keep your HNT flowing for years to come and just not be too intrusive (to the Misses in my case).

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