Thank you! This evening I was able to take down the antenna, swap out the LMR400 with the same length of 8x I had lying around, and the SWR's went from +3.5:1 back down to ~1.1:1, as it was tuned at. Quick proof something was wrong with the feedline, so tomorrow I'll take the multi meter to it and see exactly what the problem is. Not much of a coax assembler, but I guess I have to learn some day.... By far the best Ham channel on TH-cam. Thank you again.
Hi Dave Mike, K1FNX here glad you are feeling better............ something else to do is "hipot" test the cable........... I built up a very simple test fixture using two back to back 24 v doorbell transformers such that you put 120Vrms on the cable. Put a 60 watt incandescent light bulb in the primary such that if the cable breaks down the light bulb will light. If you are going to test the cables you might as well do everything just to make sure 73 and feel better
These three tests will get you through life dealing with electrical trouble shooting. I learned these at a diesel mechanics trade school during our electrical systems training. Shorts, opens and grounds.
Hi Dave, So glad to see you looking better, I hope you are feeling much better too! Good vid as always. I really like the battery & light idea for long distance; one person testing. I'd like to add please, that when someone does the center pin to shield test, it is ALSO important to do a second test on that with the Ohm meter on the highest scale to test for high resistance leakage! During that test don't touch the probe tips or the coax connectors... if you have ANY resistance you have an issue - maybe moisture or a solder flux contact, or one or more improperly trimmed shield wires making a slight & intermittent contact. Back in the 70s, I built a project box w/2 so-239's, banana jacks (for the meter) & a few DPDT switches. I would connect both coax ends up & then go thru the sequence... then I'd do it again while moving the coax behind each connector to test for intermittent problems - and that was good, because back then I was still learning how to solder on those pesky pl-259's.. I found a few issues to fix. If I redid that project today, I think I'd add the remote test ability and also a signal injection port to do advanced RF frequency tests too. Can't wait for the next installment Dave! 73!
Can you cut a bad cable near one end? Tests good so you have a jumper cable. If bad, figure out how. Now you have a slightly shorter long cable to attach a connector that you want. If good then the short is somewhere in the length. Cut in half till you get to the point where you don't mind throwing away a length vs. the cost of connectors, etc.
You’re looking better every day Dave and thank you for always keeping videos very understandable not everyone does that I had to make up a 125 foot piece of LMR 400 as well as 2 - 3 foot jumpers a month ago everything checked out good I even have the exact same Harbor freight tester I think I paid 7 dollars for like 20 years ago and even yesterday I had to check 2 runs of coax. 73
Thanks Dave. Another informative video. Having more time to spend in my shack since my retirement the information is very useful. I've been wondering about my buried coax that runs to my vertical so these tips will help. Take care and have a great New Year.
Quality checks on electric cords also is important. Some years ago in Hawaii a co-worker was repairing a power cord and did not do any simple continuity or shorts test. Plugged it in and was instantly in contact with 240 volts. We had to kick the cord way from him. We all learned valuable lesson there
Dave Casler- just founf this video, my question, with the prices of decent cable being a bit pricey, is it possible to test a long run of cable and find out where exwctly it is bad?
I made something very similar... But I used an old motorcycle horn. No need to see because I can hear it. Works great if your shack is in the basement.
Just a warning about Harbor Freight. I got one of those meters on a free coupon about ten years ago. It read 12.4 volts when my "good" meter read 12.0 volts. I wound up using a calibration source to testthem both. The HF meter was a full 0.4 volts off, which is 40% of a standard 12 (12.8) volt battery's power. After I calibrated it, no problem. But out of the box? You may as well use a test light!
Some of the antenna analyzers can test coax at RF. Some can test and tell you how far down the coax the short or open is. Coax can be damaged and check good for DC but not work for RF. I had some that got smashed, the space between the inter and the outer changed. They were almost touching, only about the thickness of heavy paper apart. That was almost a RF short.
Another little gem of a video - thank you. BTW, you are looking a bit better in this video - that is a good thing - you had all of us worried. Take care, all the best to you and your family. Michael VA6XMB
OK simplicity is best, if your fingers are touching probe, you become impedence? Just a question. I am a electrician by trade, not much electronics testing goon on in my field.
We try to avoid touching the probes with our fingers during a continuity test. It’s possible to read continuity through your body through a parallel path
No. The spot the short occurs, would start to generate heat. Because that is where it connects + to -. Eventually burning the wire in two. And there is your bad spot! Hopefully, you don't set anything on fire, doing that test!? But, you could cut out the bad spot, and remake 2 good cables.
I see the cables that shorted were soldered the rimp was fine, That is why I started crimping all me and coax cables its faster and much easier overall.
Could have used a vna or rig expert to measure the length electronically. Also could talk about how to do measurement for coax on a particularly freq. just a tip 😉 KC3ONO
Thanks Dave . Made it to the end of the video and typed this before rushing out to the garage to check all my cables ! 73's from the UK.
Many thanks for showing the test with the led light, it’s a brilliant idea. I’m going to try that 👍🏾
One of the best video I've seen that shows multiple ways to test a coax cable. Big thank you!
Important often overlooked topic.
Thank you! This evening I was able to take down the antenna, swap out the LMR400 with the same length of 8x I had lying around, and the SWR's went from +3.5:1 back down to ~1.1:1, as it was tuned at. Quick proof something was wrong with the feedline, so tomorrow I'll take the multi meter to it and see exactly what the problem is. Not much of a coax assembler, but I guess I have to learn some day....
By far the best Ham channel on TH-cam. Thank you again.
Awesome! Thanks for sharing! It’s great to see you back in the saddle!! 73, KM4OCJ
Strangely enough, I was just discussing continuity yesterday and testing new feedlines. BTW, you are looking better and better every day! '73 / Steve
This is one of the most useful and vital videos. Just carried out repairs on a long Messi pasolini cable and passed the test
U
Been waiting all day. Thanks for taking the time to film, edit and upload.
Hi Dave
Mike, K1FNX here
glad you are feeling better............
something else to do is "hipot" test the cable........... I built up a very simple test fixture using two back to back 24 v doorbell transformers such that you put 120Vrms on the cable. Put a 60 watt incandescent light bulb in the primary such that if the cable breaks down the light bulb will light. If you are going to test the cables you might as well do everything just to make sure
73 and feel better
These three tests will get you through life dealing with electrical trouble shooting. I learned these at a diesel mechanics trade school during our electrical systems training. Shorts, opens and grounds.
Love your alligator clip trick to test a wire that’s routed through many places! Thanks!!
Hi Dave,
So glad to see you looking better, I hope you are feeling much better too!
Good vid as always.
I really like the battery & light idea for long distance; one person testing.
I'd like to add please, that when someone does the center pin to shield test, it is ALSO important to do a second test on that with the Ohm meter on the highest scale to test for high resistance leakage! During that test don't touch the probe tips or the coax connectors... if you have ANY resistance you have an issue - maybe moisture or a solder flux contact, or one or more improperly trimmed shield wires making a slight & intermittent contact.
Back in the 70s, I built a project box w/2 so-239's, banana jacks (for the meter) & a few DPDT switches. I would connect both coax ends up & then go thru the sequence... then I'd do it again while moving the coax behind each connector to test for intermittent problems - and that was good, because back then I was still learning how to solder on those pesky pl-259's..
I found a few issues to fix.
If I redid that project today, I think I'd add the remote test ability and also a signal injection port to do advanced RF frequency tests too.
Can't wait for the next installment Dave! 73!
Good Testing Ideas...thanks Dave
Thanks for the back to bacis. we all need a remider from time to time. Again a great show from the master. KD9HWH.
Lifesaving video here👍🏽
I like the LED light test, I'd never even thought of that one! 👍👍
Just a heads up Dave. I believe that the red lead on your multimeter is almost severed right at the plug that connects to your meter.
That's why I invested in a non harbor freight special
Dude , thanks alot , respect from Turkey🇹🇷
Dave always has a great ideas for testing something! Thanks Dave. 😁
Thanks!
I like to use the 'beep' feature of my multimeter for checking continuity.
Can you cut a bad cable near one end? Tests good so you have a jumper cable. If bad, figure out how. Now you have a slightly shorter long cable to attach a connector that you want. If good then the short is somewhere in the length. Cut in half till you get to the point where you don't mind throwing away a length vs. the cost of connectors, etc.
THANK YOU FOR THIS VIDEO
You’re looking better every day Dave and thank you for always keeping videos very understandable not everyone does that I had to make up a 125 foot piece of LMR 400 as well as 2 - 3 foot jumpers a month ago everything checked out good I even have the exact same Harbor freight tester I think I paid 7 dollars for like 20 years ago and even yesterday I had to check 2 runs of coax. 73
Thanks Dave. Another informative video. Having more time to spend in my shack since my retirement the information is very useful. I've been wondering about my buried coax that runs to my vertical so these tips will help. Take care and have a great New Year.
Great job! Thanks.
Simple and effective! Way to go Dave.
Useful enough video. I feel though that a drawing might have been simpler for those just starting out.
Quality checks on electric cords also is important. Some years ago in Hawaii a co-worker was repairing a power cord and did not do any simple continuity or shorts test. Plugged it in and was instantly in contact with 240 volts. We had to kick the cord way from him. We all learned valuable lesson there
Outstanding, thank you!
Dave Casler- just founf this video, my question, with the prices of decent cable being a bit pricey, is it possible to test a long run of cable and find out where exwctly it is bad?
I made something very similar... But I used an old motorcycle horn. No need to see because I can hear it. Works great if your shack is in the basement.
Great idea! 🔊
Dave I got some cheap cable ends for Amazon. Is there any easy way to solder these things will out messing up the dye electric?
Just a warning about Harbor Freight. I got one of those meters on a free coupon about ten years ago. It read 12.4 volts when my "good" meter read 12.0 volts. I wound up using a calibration source to testthem both. The HF meter was a full 0.4 volts off, which is 40% of a standard 12 (12.8) volt battery's power. After I calibrated it, no problem. But out of the box? You may as well use a test light!
Really help! Thanks
great job! thank you for this help.. much appreciated!
I have a question. How do you find the value of a coax whether if it is 50 or 75 ohm on a unmarked coax?? Thanks. Mike. N2JVE
Brilliant 👍🏼
Some of the antenna analyzers can test coax at RF. Some can test and tell you how far down the coax the short or open is. Coax can be damaged and check good for DC but not work for RF. I had some that got smashed, the space between the inter and the outer changed. They were almost touching, only about the thickness of heavy paper apart. That was almost a RF short.
I have these problems with antenna cables. Perhaps they were kinked along the way. But now I know a good way to test them.
Short (pun intended) and sweet to the point! Thanks!
Another little gem of a video - thank you. BTW, you are looking a bit better in this video - that is a good thing - you had all of us worried. Take care, all the best to you and your family.
Michael VA6XMB
Can an antenna analyzer or something with an oscilloscope show how far away the short is?
Yes, most any analyzer has that function. It is simulating a TDR (Time domain reflectometer)
I was thinking the same thing.
Like the video but I would ensure the battery is fused to prevent possibility of a short while testing 👍
so how do i know if the cable is leaking? and how can i measure 50ohm true it?
best regards
Thank you thank you thank you!
OK simplicity is best, if your fingers are touching probe, you become impedence? Just a question. I am a electrician by trade, not much electronics testing goon on in my field.
Check the coax before you put ends on it?
Reminder: unhook the cable from the antenna. If you cannot, see whether the antenna operates at DC ground. This show in your meter as short.
We try to avoid touching the probes with our fingers during a continuity test. It’s possible to read continuity through your body through a parallel path
that is indeed the wrong way and he most likely got a false reading
Hey, it works for general testing. This wasn't a science lab experiment.
@David Castler, You need a new battery in your meter.
Thank you Dave. Great stuff. 73 de KG7LOI
Brilliant!! 73/K6DW
Not sure if I understand. If you had a short between center and outside the light would still light up.
No. The spot the short occurs, would start to generate heat. Because that is where it connects + to -. Eventually burning the wire in two. And there is your bad spot! Hopefully, you don't set anything on fire, doing that test!? But, you could cut out the bad spot, and remake 2 good cables.
I see the cables that shorted were soldered the rimp was fine, That is why I started crimping all me and coax cables its faster and much easier overall.
Could have used a vna or rig expert to measure the length electronically. Also could talk about how to do measurement for coax on a particularly freq. just a tip 😉 KC3ONO
Too many watts and a long key time on the shorted pieces Dave..hihi.
73, kb8qlz
Wow i learn
Thanks for the reminder. N0QFT
You measure the resistance of your body 🤦🏻♂️
DAVE YOUR SKIN IS PICKING UP THE RESISTANCE,YOU CAN'T TOUCH BOTH ENDS WITH YOUR FINGERS,NO SKIN
Tu mesure la résistance de ton corps 🤦🏻♂️
You measure the resistance of your body 🤦🏻♂️