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Author Topic: Coax ends  (Read 5912 times)
WB4IVF
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Posts: 114




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« Reply #15 on: November 13, 2017, 04:41:53 PM »

Neal -

Which insulation tester and voltage setting do you use?

Thanks,
Howard
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N6YFM
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Posts: 517




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« Reply #16 on: November 13, 2017, 10:25:02 PM »

Neal -

Which insulation tester and voltage setting do you use?

Thanks,
Howard

Extech model 380363.   1000 volts.
I also played with a 1,500 volt megger, but it cost too much, so this one has to do well enough for me.

https://www.tequipment.net/Extech380363.asp

Cheers
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WB4IVF
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Posts: 114




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« Reply #17 on: November 14, 2017, 03:20:20 PM »

Thanks much for the info!  I use an antenna analyzer to check my cables too but had never heard of an insulation tester. 

Howard
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K5TED
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Posts: 101




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« Reply #18 on: November 14, 2017, 07:58:07 PM »

Settled on crimp connectors several years ago after a wifi project with lots of N connectors involved. They are all still running like day one, in the elements. Good quality crimpers, cutters, stripper, cable, connectors and a bit of copper paste or silicone grease here and there on outdoor stuff, and properly applied heat shrink are key. Liquid electrical tape is great.

My Field Day kit includes plenty of crimp RG58 connectors and a roll of good quality coax for those one-off jumpers and spur of the moment workaround or ad hoc antenna feeds. Much quicker to deploy than solder.
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WB4SPT
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« Reply #19 on: November 15, 2017, 07:29:46 AM »

Thanks much for the info!  I use an antenna analyzer to check my cables too but had never heard of an insulation tester. 

Howard

short course:
There are two kinds of popular HV testers.  The first is IR or insulation resistance, it measures in Ohms, and is done at some moderate voltage, 500V is typical.  It is best where there is a threat of compromised INSULATION.  Like, "does my foam coax have water soaked in it".   
The second type is a "hi-pot" tester.  This is the best tool for looking at air clearance issues with new builds;  ie "do I have a flying piece of wire braid in a bad place".  This instrument is a pass/fail at a ceratain voltage, usually settable to higher values than a IR tester.  It is responsive to low current arcs.  It would be the instrument of choice to test gas tubes, and even the adjustment on a "blitz bug", etc. 
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WB4IVF
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Posts: 114




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« Reply #20 on: November 16, 2017, 08:03:55 AM »

OK, thanks.  Looks like these testers can be useful equipment to have. 

Howard
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KE0ZU
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Posts: 309




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« Reply #21 on: November 19, 2017, 08:10:10 PM »

After about 40 years of coax solder type connectors, I switched to crimps about fifteen years ago.   As others have mentioned, good tools are a must if you want to have good results.   Don't think I'd run out and buy a megger or hi-pot tester though.

Mike
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AF6AU
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Posts: 63




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« Reply #22 on: November 27, 2017, 10:35:53 AM »

All of us old dogs out there know that good soldering is an ART. You would be suprised at how many Generation "X" and younger think the best use of a soldering iron is to create burns on wood, or melting plastic. They think soldering as some sort of gluing process.

My father use to teach lead sheath telephone cable soldering, and I learned from him. Indeed an art form.

I always enjoying watching a newbie try to solder without cleaning off oxide from everything. Another fun one is they call you up saying nothing works, and you ask if the soldering gun tip nuts or screws are snug. Or they are trying to solder some aluminum or zinc alloy..

Years ago I trained many people on how to solder copper plumbing, and when they see solder flow uphill into a vertical joint, the facial expressions are worthy of a photo.

Today, same rules apply but surface mount components use tiny tips, thin solder, no caffiene, and a magnifier.

It's a learned skill, and soldering connectors, wires, lugs, memory batteries, from SMT parts to #4 wires tied with a Western Union splice (what's that??), yep a good job without roasting insulation or having a cold joint, is indeed Art..
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NEVBEN
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Posts: 106




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« Reply #23 on: November 27, 2017, 11:29:02 AM »

For an amateur radio operator just beginning there are a lot of things to do besides make patch cables.  Just the investment in quality cable termination tools is significant and there's nothing wrong with outsourcing that when your cable needs are minimal.

A beginner isn't always looking at investing in equipment to strip, crimp or solder and test cables, which can easily cost many hundreds of dollars.  I've been in amateur radio for nearly 7 years.  I've built my own transmitter, receiver, antenna tuner, played with VHF/UHF, repeaters, APRS, TNC's, obtained a General and then Amateur Extra license, played with QRP on HF, built a keyer for CW, done portable ops, field day and on and on.  In my nearly 7 years I have soldered one (1) PL-259.  I have also purchased two (2) PL-259 crimp cable ends pre-installed on a patch cable.

At the moment, I need two more PL-259's to insert a surge arrestor on a 25' LMR400 feedline.  After that, I can't forsee needing another cable end for years.  I'll probably end up melting some dielectric because I've had no practical opportunity to develop my skills and no good justification for costly strip and crimp tools.  So I can either melt dielectric or buy two crimped 15' patch cables.  If anyone wants to send me a box of scrap LMR400 and solder PL-259's to practice on, let me know.  A tester would be nice too.
« Last Edit: November 27, 2017, 11:33:02 AM by NEVBEN » Logged
N1RND
Member

Posts: 12




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« Reply #24 on: December 11, 2017, 04:21:42 PM »

I totally agree, HAMS should be able to make their own cables.  I'm not going to explain how because my 40 years of experience would take too long here.
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KJ4RWH
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Posts: 212


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« Reply #25 on: December 12, 2017, 08:06:22 AM »

My hand made patch cables not only have measurable gain but are elastic. When stretched to their design maximum of 200% any right angle bends automatically create a wave guide to ensure constant impedance.
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N1RND
Member

Posts: 12




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« Reply #26 on: December 12, 2017, 02:13:39 PM »

I hope I was not too sarcastic. 
The first thing is to use rg213 instead of rg8 , the solid dielectric is more forgiving than the foam dielectric.  Next is to do what I saw in an issue of QST from a while back.  After you prepare the end of the coax, (according to the instructions in the ARRL manual) you tin the outer braid and then trim it to length with a mini tubing cutter.  Now you have a nice clean edge with no stray strands.
Place the screw down ring onto the coax, "screw" the connector onto the end of the coax.  The tinned braid should show thru the holes, the center conductor should come out a little past the end of the center pin.  Now here's the hard part.  People complain that their iron is not hot enough and "get welded to the connector" before the solder flows into the holes.

Have 60 watt pencil iron ready.  Heat body of connector with mini butane torch for about 4 seconds, immediately solder holes with iron.  Let cool for a few minutes, repeat for center pin.

I've been doing connectors this way for a long time and don't have any problems.  The preheating the connector with torch keeps the connector from acting like a heat sink and sucking the iron too cold.
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