How to Measure Coax Loss (w/ Bird Wattmetter) - Coax Part 2

#HamRadioTV #HamRadio #AmateurRadio #CoaxLoss
Fiori Films Presents Ham Radio TV: How to Measure Coax Loss - Part 2
In this video Kevin N6VLF, will show you how to test your coax.
Links to Charts:
electronics.st...
qrznow.com/coa...
Link to Part 1:
Is Your Coax Good & The Right Length?
• Is Your Coax Good & Th...
You might have a 100 watt or a 50 watt radio, BUT your antenna might only be transmitting 10 watts by the time the signal gets there. The higher the frequency the more loss you will see in your transmissions lines.

[@fordmustanggtish]

Super great explanation and a wake up call on how much signal we could be losing with our current setup. Great job folks! VY2KW

[@HamRadioTV]

Thank you!! A lot of things will just work, but could it work better? 73!

[@flatlander523]

Kevin you are a natural teacher. I really enjoy the videos. I wish I could pull a copy of the charts and tables you are using.

[@HamRadioTV]

Thank you! The charts that we used were just from a Google search. There is a lot of good ones out there.

[@gregkurtz9533]

This was a super demonstration and explanation. Bravo for the instructor and club that did this. - N8IOK

[@HamRadioTV]

Thank You! Yes, we are very luck to have the people we do in our club. I recognized this right away and started recording them to share. Have you seen the Part 3 to this series? Here is a link: kzbin.info/www/bejne/nKKplH6Xrb6Uhsk ~73 KM6FAK~

[@arlenewolf5260]

Thank you, that was a great video. My wife is not a ham, I am a little into emergency preparedness. My new home will have about a 50' tower. I also have some elevation (we are in the foothills of the Great Smokey Mountains). I am considering putting up a (25W) GMRS repeater (2 GM300's with a RIC and a RX preamp) up for her use with me on ht's. I know that my GMRS numbers will compare somewhat near the 70cm numbers (a little worse). I am putting up a few antennas on the tower (Two 2m/70cm Comet's one for a dual band radio and one for a DMR repeater I own, a Discone [so I can mess with a variety of freq's], and a 10/11M ant to talk with local rescue squad friends on CB with [I will try to get them on GMRS]). I am not concerned about the price (I will cry later) I was thinking of having my feed line being Andrews Heliax LDF-6 (I think that is the 7/8" you showed) or LMR600. I hope the hard line run will be less than 100'. After watching your video, I think that is probably the best I can hope for. 73 and thank you for the video.

[@beekeeper8474]

I use lmr-400 for coax that doesn't need to move and rg400 for moving and jumpers. Also all of my 2m/70cm antennas have gain to help recover what is lost in the coax.

[@brentjohnson6654]

New sub here. I just watched him show measuring VSWR on other cables and his explanation was excellent. This video is excellent as well. Thanks for instructing us prospective HAMs

[@HamRadioTV]

Very Cool! Thanks for stopping by and joining the channel! Kevin/N6VLF is a great Elmer and I'm glad he's not camera shy!

[@davep6977]

Great presentation 1/2" & 7/8" Andrew LDF heliax is my best friend. It's worth the $$ for me. 30Mhz and below is LMR400. Above 30mhz 1/2 hardline. "Your antenna system is 90% of your station" W9DLP

[@HamRadioTV]

Thank You!!

[@americaswayout4489]

Great video for new folks and makes the feedline quality real. My question is the 75ohm hardline. I found some transformers to get it back to 50 but not sure they will work at Vhf or Uhf frequencies. The local cable folks did major repairs and rebuild and I got the spool ends one over 400 feet and with all my stuff down after the 155 MPH Hurricane Michael and having to totally redo plus add new antennas. I had not been active and my 25 years after getting my ticket, much needs refreshing and relearning or just to be learned, and after 70 things come slower. Thanks for your channel, I will be viewing to get back up to speed.

[@Devin82m]

Great video! Kevin explained everything so well, thanks!

[@HamRadioTV]

Thanks! Yes, we are lucky to have Kevin!

[@BasHeijermans]

Bad feedline, either coax or twinline will kill your signal and reception. It's amazing how many people don't understand how they work and why you should avoid the cheap stuff. At high SWR it matters even more, as the signal has to do the trip one more time on the reflected signal. It's all attenuation, SWR is relative unimportant when attenuation is low. People really misjudge the importance of attenuation, it's the worst number you can have when it goes up. High attenuation turns the best antenna into crap, no joke.

[@genepierson1728]

Great video! Thanks for uploading. It says part 2. Looking for Part 1. Anyone have the link to it? Can't find it.

[@socialite1283]

Great session. Thanx.

[@HamRadioTV]

Very welcome, thanks for watching!

[@thomasjames5722]

Very helpful, thank you!

[@HamRadioTV]

You're welcome!

[@TheRealDanNguyen]

great video

[@davideisenberger6197]

Excellent! Thank You for your time! 73 de K8KEM

[@HamRadioTV]

Glad you enjoyed it! 73 KM6FAK

[@davidhayden6724]

Excellent video with great information! Thanks, David K4UVX

[@HamRadioTV]

Thank You!

[@Fox250R]

Rg8x vs LMR240 18 vs 9 feet for 27 mhz thank you 🙏

[@seeharvester]

Now I gotta go watch a math video to figure out how to use the log button on this frickin' calculator. :)

[@terryglenweaver]

I should title this comment: *Is adding additional coax length worth it?* With the $8 calculator take the 42 watts input (to the cable) and subtract the 25 watts output (from the cable) and 17 watts is the wattage loss. This translated to 2.25~2.35 db loss ( db=decibels ). This db gain and db loss is the gain or loss capability of one's radio station. Now, add another 50 ft of coax (as he explained) and consider that factor of loss... But wait... Adding the next 50 of coax and the loss of the initial 50 ft db loss and this could seem significant, except there is one more factor that needs including. If this 50ft and the additional 50 ft both are used for elevation and that elevation put Your antenna array significantly above obstructing objects... though Your station may have suffered major power losses due to coax loss, because of obstructive object clearance the effective gains may completely justify lengthening the coax. Consider this... You have your watt meter and a dummy load and PL connectors on both ends of your coax. With that you do not require any chart or excessive math. Simply hookup your meter to your radio (without whatever coax you will be testing AND a dummy load on the antennas side of your meter. Take a power output reading and write it down. Now take the meter off your radio and hook it up to one end of the coax, while leaving the dummy load where it was. Hook up the other end of the coax unto your radio and take a power reading. The difference between these two readings is the amount of power loss that piece is coax causes and at a rate of 2.25~2.35 db gain per 50 feet. This is with THAT PARTICULAR COAX this man referred to... I believe it was the RG58mini. 73s

[@anthonyleeser4571]

Where online can I find those charts? Fascinating presentation!

[@davep6977]

www.w4rp.com/ref/coax.html www.universal-radio.com/catalog/cable/coaxperf.html

[@HamRadioTV]

Thank You! I don't have the exact site but there are multiple. When searching the keywords are coax lost chart. You can also look up the specific coax.

[@HamRadioTV]

@@davep6977 Thank you for posting these links!

[@JayN4GO]

What about closed hf antennas” loops”. Still the half wave coax rule for that? Say 40m delta, 66’ coax “8x” minimum?

[@HamRadioTV]

Yes, is the short answer. Any antenna you use should have a 50 ohm impedance with an SWR as low as you can get it. As for the coax, if it has RF on it, then length will matter. The type of coax will then dictate how much power/dB will reach the antenna. Remember, the dB loss will also effect how well you receive a weak station, it goes both ways.

[@PicaDelphon]

Need a Link to the Charts So Other can print it out and fallow along..

[@HamRadioTV]

Thanks for the recommendation! I just put two links in the description of this video.

[@andreasyufrizal73]

Nice info

[@HamRadioTV]

Thank you!

[@PatAutrey]

Please confirm how you got 33.8 watts on the calc - no joy

[@stevenlawhon3695]

Is this for wire antennas only?( multi-band vertical?)

[@christophersmith1155]

non of my calculators have log -4.7 / 10 = .-47 ,,, -.47 x 100 = -47. how in the world did you get 33.8 ?

[@MAWazaLLC]

Very informative. - KC3HUL

[@HamRadioTV]

Thanks!!

[@dr.nunzio_improta]

RG58 ???!!! I didn't even use it in my car forty years ago.

[@HamRadioTV]

lol, everyone has different standards and budgets.

[@jvolstad]

Who is that old man to your left?

[@HamRadioTV]

That was Ruff / K6DME, now a silent key.

[@RESISTAGE]

I may ge wrong but u do not want any energy radiated go back to your radio. u want it go into the air not back to radio.

[@andykurasaka4231]

11meters forever

[@stevenlawhon3695]

1 db is 20% or 1/5=20

[@hahawki]

I get 32.8

[@WanderlustWonderscape]

Thankfully that annoying band next door stopped playing at 2:15.

[@concernedpatriot9314]

That was OK 👌 Attention this cymbal is not a white supremacy hand sign ! So when I say this was ok it means the same as ok 👍!

[@HamRadioTV]

10-4

[@HamRadioDX]

Thanks, very informative video and a great presentation. 73, Hayden

[@HamRadioTV]

Thanks Hayden! I got your email, all good stuff. We'll be in touch dude (or is it mate) :)

[@HamRadioDX]

Ham Radio TV No problems at all. Definitely mate! 👍