Survivalism & Self Sufficiency Topics > Amateur Radio How-To's

best practices for making coax patch cables?

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Smurf Hunter:
so now that I'm "legal" and have all the gear to start transmitting, the next logical step is to begin messing around with homebrew antennas.

I'm seeing a ton of conflicting information about what style of coax and connectors to use.

e.g. this old timer demonstrates how to use RG-6 (which I believe is the cable TV type) and wraps duct tape to increase the thickness for the connector sleeve:
https://www.youtube.com/watch?v=tg2lmDETJTs

After I decide on what sort of cable is "good enough", what about the end pieces?

eBay has all sorts of bulk packs that ship for just over $1 each.  That seems reasonable for the small quantity I'll need, but are they "good enough"?
http://www.ebay.com/itm/NEW-20-pack-lot-UHF-PL-259-male-solder-on-RF-connector-plugs-for-RG8-coax-cable/271321083620?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222003%26algo%3DSIC.FIT%26ao%3D1%26asc%3D22854%26meid%3D7065634343819981048%26pid%3D100005%26prg%3D9833%26rk%3D2%26rkt%3D6%26sd%3D350958835907&rt=nc

In summary:

What are considerations when choosing coax?

What are considerations when choosing PL-259 end pieces?

Chemsoldier:
  :popcorn:

Carl:
For my use ,RG8X and PROPER PL-259 connectors and INSERTS.
The RG8X has lower loss than many RG8 (thicker) coax cables and
I have had some in the air for over 25 years with NO problems.

Here is where I get coax,by the foot and PRE--MADE  lengths
from 2 feet to 125 feet . Many videos show how to solder coax
and look at a few to get ideas. Use proper inserts to adapt coax to
the PL259 to protect your work and the strength of the cable.


Cable by the foot
http://www.randl.com/shop/catalog/index.php?cPath=11020

Pre made, the Jetstream series is my favorite
http://www.randl.com/shop/catalog/index.php?cPath=11030

Also good weather-proofing is a MUST ,water and moisture will degrade cable quickly.
Self vulcanizing tape ,usually silicon,with a friction tape  over wrap to protect from UV works well.
Also limit free hanging ( tape to support every 5 to 10 feet) and sharp bends and CRUSH should be avoided.

Just my thoughts , and suggested cable.
The pre-made lengths are so close to component cost,I just buy ,unless in a rush.

When making a cable,ohm test for complete , center to center-shield to shield connection and
center to shield should always measure as OPEN...infinite resiatance.

TexasGirl:
RG 59, RG 6, are "TV" type cables with a 75 ohm impedance.  They are rarely used in 2-way radio equipment because our gear is designed for 50 ohm antenna systems.  (Yes, a center fed dipole is technically 75 ohm, but your rig wants to see 50.  That's what baluns are for.)  Don't use these cables for ham use outside of ATV.

RG 58, RG 8, RG 8X (sometimes called "mini 8"), RG 142, and Heliax hard line are commonly used 50/52 ohm coax cables.  You will learn which ones to love or hate under which circumstances.


TG's ramblings for consideration...

I prefer soldered connections over crimped, moisture or corrosion can get in a crimp.  Solid Polyethylene dielectric repels moisture better than foam dielectric, so solid dielectric makes better outdoor cables.  RG 142 is very flexible, commonly used as jumpers for test equipment.  RG 8X is only slightly larger than RG 58, but has lower loss and higher power handling similar to RG 8.  Because it has foam dielectric, it's not best for permanent outdoor installation, but is hard to beat for a field deployable rig.  (Use RG 59 reducer barrels in PL 259's with RG 8X cable.)  Adapters are great in a quick fix, but they can cause trouble over time in permanent installations, every additional connection has some sort of loss or imbalance.  Use correct cables where possible.  Cable loss is more important at higher frequencies (2 M, 220 MHz, 440 MHz).
 
Good antenna projects to begin with are longwire dipoles and J-poles.  The ARRL Antenna Handbook is great to have around.

Happy Soldering!

~TG

Carl:
Not to sound argumentative , but to ramble on the subject.

But ,in my understanding:
Foam core is not an issue with moisture (though a foam outer jacket would be) A properly sealed PL-259 will not let water into the core and FOAM has a more consistent dielectric and RF characteristics,it is MORE STABLE  (that's why Mini_8 is better and lower loss) though 100 feet of Mini 8 still loses almost HALF of your VHF power.

The great jacket,heavy shielding and thicker stranded core all lend to the above average RF characteristics and below  average COST of the MINI 8. It is NOT the best,but it is the best balance of function and economy. In my opinion.

And on to 70 ohm coax, your radio expects a 50 ohm load,and 50 ohm coax is a good choice.

BUT a dipole is accepted as 72 ohms ,or so,impedance .( go figure that one out) and verticals often are 31 to ? ohms.

In actuality the trouble with  other than 50 ohm feed line is finding the connectors to mate it to 'our' devices.
Noting that HARD LINE is the often described  BEST for HAM use ,though most hard line is 70 to 90 ohm impedance.
and let's not even go to the fact that 300 and 450 ohm ladder line are the lowest loss choice for many antenna applications.

Please don't think this a critical view of you or your thoughts on feed line, it is not.In fact,re-reading, we are much in agreement. Though you gotta' tell me how the core material is responsible for keeping water out, I always thought it was the outer jacket. Once water gets past the outer jacket,RF characteristics and your signal really suffer. But often ,due to
high loss, a corroded shield reads acceptable SWR while performance of the antenna suffers.

When ,and why,did SWR become the yardstick to judge antenna effectiveness or even "TUNE"??
As once cut to length,any trimming will only diminish antenna efficiency ,though it may make the radio happier,or the operator.

TG and others , I am interested in your thoughts on this often argued subject
TG??? wow ,you really are well versed in some heavy stuff. we have close to
the same opinion,viewed from different angles.

All of my feed line is 50 ohm,except for 300 ladder line on the G5RV.

Boy,did I ramble, maybe the MEDs I take are needing adjustment.

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