What Is Velocity Factor By YouTube Elmer Jim Heath W6LG

Jim Heath W6LG discusses Vf or Velocity Factor related to coax cables and antenna wire.

[@tixilx]

“Spend time in the company of a wise man son and you will become enriched” ...... Well after spending time with this wise man I certainly leave enriched ... Thank you Sir ☘️

[@MrDeeejaaay]

Thanks for another excellent video, Jim. Good to talk to you tonight. 73, WA7DJS

[@greasydot]

Good morning Jim. Nice to see/hear you. Thanks for the info.

[@angelhelp6819]

Hi Jim good morning 🌞 I like that video are you feeling better I'm glad you're talkin any new video very excellent 👌 videos I am glad you're back and making them you're feeling okay just take your time you still making new ones and I'm gladI was thinking of you hope he's feeling keep making them okay I hope your medication side effects with no side effects 😃☘️☀️ good luck ☘️

[@batfalcononyoutube]

Since you already have a great experience on cable manufacturing, it would be a nice extension to this video a study of how and why they choose each and every dielectric for each cable, therefore what type of cable shall we use / choose for the lower ham radio bands and what for the upper ones. As always, thanks for the knowledge you are spreading. 73 de SV1SLB

[@S_m2.00]

Great video.. Mr Jim

[@Brandon_B.]

thanks Jim very helpful & informative

[@DonDegidio]

Hi Jim, Glad to see another video and that you will be producing more. I think generally the solid dielectric coax has .66 and the foamed has .82 VF. Stay safe. 73 WJ6U

[@aldimore]

I feel smarter! Thanks Jim

[@TI2GBB]

Happy to see your videos back! Thanks for clarify this important topic for us. 73s From Costa Rica! TI2GBB

[@MrRegzxzx]

Thank you Jim, always very informative 👍

[@virginiabugbee5973]

Thanks for another interesting and informative video. Just passed my technician exam and wanted to thank you for your good explanations! 73!

[@miken6imy]

Looking forward to seeing the coax feedline comparison in your next video Jim.

[@hornhospital]

I finally understand what velocity factor means with regard to coax thanks to your excellent explanation. Thank you.

[@DK5ONV]

Thx for another great documentary video, Jim. Hope you are save and doing fine. Vy 73's de Günter from germany. By the way, I passed my licence upgrade exams to A-Class last tuesday 3rd of November. And I signed up for a second youtube acount with my new final callsign "DK5ONV" Happy sunday @cross the HAM Nation

[@K1QS_Radio]

great explanation of coax. Please keep the fundamental explanations coming. I am honored to call you my virtual Elmer... Oh, BTW. can you cover real ladderline? not the windowed plastic stuff, but the 600 ohm ladder line. Losses, care and feeding.. etc? thanks.

[@alanjames4526]

Hi, Jim. Great video and looking forward to the next one comparing coax. 73 Alan KZ6B

[@hellominions1604]

Great content, never understood this till today, thanks very much.

[@PF9Z-HamRadioDXStation]

i'm sure that i can write a book already with all the nice learned things of ya ;) Keep on Going Jim...73s Sascha PD9Z

[@dudeski934]

Thanks for the good informative video

[@mcnugget91]

Thanks Jim, I always learn something new from your videos. You are a great Elmer to us all! 73 NF1T

[@johnbailey4664]

Great stuff Jim

[@duanecjohnson]

Hi Jim; I use 4” open wire 400 ohm balanced line, about 150’. This drives a 250’ center fed Duplex antenna. I like the the open wire line because the velocity factor is about 0.95 and the loss is about 2db/100’. This works very well. Of course this requires a transmatch antenna tunner. Mine is an old Johnson Viking 250W. Will you be discussing open wire line in the future? redrok AD0TJ

[@battlestarone]

Great vids,,i an sick of arguing with ham about velocity in wires and coax cable and the effect on accurate swr readings in the shack,,to the point i have gave up trying to explain how important it is to take these factors into account when installing an antenna...regards Gm7jds

[@margaqrt]

The velocity factor is needed when calculating the electrical length of your coax. Some purveyors of amateur radio folklore contend that certain lengths of coax transmission line are to be avoided. I suspect this question is mostly superfluous in amateur antenna applications. When the feed point impedance of the antenna matches the characteristic impedance of the coax, we are concerned only with loss. However, every myth has a grain of truth. Certain lengths of coax are used as matching stubs--they are an impedance transforming device, when we are dealing with a load whose feed point impedance is a mismatch. Suppose you have a half wave dipole for 40 meters and you chose to operate it on 20, the feed point impedance will be through the roof. The impedance is essentially infinite in this scenario and it would be impossible to deliver energy to the antenna. If you had an odd multiple of a quarter wave of 20 meters as the length of your feed line it would invert the high impedance at the feed point to a low impedance in your shack, at the tuner. The operator sees a nice low SWR reading and assumes he is good to go. Perhaps electrical length (as computed via velocity factor x physical length) is an important consideration after all. 73 Jim.

[@akcma5705]

great info, thankyou!

[@JimN5QL]

Great video Jim! I knew about velocity Factor and I knew how to use velocity Factor but I never knew why until now! Thanks for the great video looking forward to your next one.

[@sarbog1]

Thinking about getting my license again.. I was Wa0tiu back in the 1960's so much has changed with ham radio...... love software defined radio.......

[@elmoreglidingclub3030]

Great stuff, Jim. I’m brand new to amateur radio (about to take the Tech exam) and I learn a lot from your videos. This video rekindled something I’ve wondered about: Insulated versus bare wire dipole antennas. Several have told me it makes no difference. But since the obvious use of insulation on wire is to insulate the electrons from the environment it’s hard for me to imagine how the insulation doesn’t, then, affect incoming and relatively weak signals.

[@sarbog1]

Velocity factor is a property of the space that  an E&M wave passes through ....... not the the electrons ...... love your videos .........

[@sarbog1]

When light passes through any medium other than free space it slows down.......

[@1fanger888]

Hey Jim. Good to see ya! Thanks for the teaching. KC3BXZ Joe 73

[@TomG2NV]

Hi Jim, First class as always! Hope your well and back on the air? 73 from your friend Tom in England G2NV

[@JayN4GO]

For some reason KZbin isn’t notifying me on your vids Jim. Bell checked , all. 🤷🏼‍♂️

[@af4od02]

Thanks for the info. Looking forward to the next video. 73

[@lwoodt1]

For many of us, the coax is a very confusing part of our radio system.

[@Proc3000]

Love the videos Jim. Love the explanation of velocity factor. All your videos are easy to understand. I wish I bothered looking at those things when choosing a wire. Im running probably 45-50 ft of LMR 400 ultra Flex though for VHF/UHF so its probably not a big deal. But for the future I know I need to look at other items.

[@paulhastings3109]

Thank you Jim. Trying to duck the Hurricane I hope it keeps going East. Have a good day

[@MenAtWorkMedia22]

You are the man!

[@abfig78]

Love your videos! Can you make one on the mag mount antenna and a bolted on antenna and the difference. Also talk about the ground plan dealing with both.

[@ham-radio]

Thanks. For what band? Frequency makes a difference. 73, Jim

[@abfig78]

@@ham-radio 2 meter and I play with 11 meter too. I know a lot of hams don't like it, but most of us cut our teeth on the ol CB radio.

[@tomw5vlt119]

Jim, haven’t worked with velocity factor since the Exam, and frankly forgot. A practical example would add a lot to a video on the subject, including the math that I recall is not difficult. So going from memory, and you started to do an example, it’s “used when” calculating an antenna length, and so if “in application” one wanted to measure a 20m antenna length, you would multiply ... go through the math on a white board please ... to illustrate the example clearly.

[@mikebavoso26]

Hello Jim, another great video. You mentioned a video about building your own coax connectors. I was unable to find it and wonder if it could post a link to my question. Thank you

[@carolmartin7042]

Thanks. Glen, N0QFT

[@kc8njnsunday24]

Like your content! Unrelated- Are you worried about EMPs, lightening and power surges beyond a normal GFI protection? I’m reading about devices that can protect your whole house.

[@2metercrew389]

👍👍👍

[@leighdexter7493]

Happy to find your videos. Any tips for someone learning and listening in eastern Nevada county?

[@ham-radio]

There used to be a very active club up there. I think there were also a couple of contest stations. Maybe you can do a check for callsigns using the zip code. I am sort of finding my way around Placer on line. I am confined to home for the obvious reasons. Listen on HF. Listen on 40 and 20 meters. 73, Jim.

[@potshot23]

Very good info, Jim. one thing I'm not sure about is if you extend the length of the coax, but you use 2 coaxes with different velocity factors, what happens to the velocity factor??

[@ham-radio]

I asked a very good friend about that exact question. The answer appears to be; just do a weighted average. How that sound to you Steve? 73, Jim

[@JSambrook]

Is there any difference between electron movement on the inside of the shield vs. the outside of the shield?

[@chrismayer7762]

Great explanation....73 KE0ZSU

[@battlestarone]

Jim what are your thoughts on Walt Maxwells idea that feedline length and swr have nothing to do with each other,,i work with the odd multibles of a 1/2 minus velocity factor of the cable always and that works for me,,i get the same reading at both ends of the cable,,,but so many disagree..,,regards Brian gm7jds.

[@ham-radio]

Well, excellent question!!! Maxwell knew more than anyone. Sure the 1/2 wavelength will given good results when analyzing an antenna. I am convinced that it makes not difference. The energy is radiate no matter the length if the antenna and feedline match. That is very important. A 1:1 SWR may or may not be the resonant spot or frequency. The resonant frequency may have an impedance of 30 ohms. Where reactance brings the SWR to 1:1 is not the same place. 73, Jim

[@robertramos36]

good day i was wondering why do hf radios have tuning on them when you need a tuner for antennas never can figure that one out have a great day KF6SIF.

[@ham-radio]

Jim W6LG 5:59 PM (1 hour ago) to KZbin Hi Robert, I have read your question 3 times and I am not sure I know what you are asking. But, I will give it a try. First, most of us old guys we don't call them radios. They are transceivers. Radios are receivers. You said that "hf radios have tuning on them...." Did you mean that they have so called antenna tuners built-in? If so, not all transceivers have antenna tuners. Some of mine do not. Antenna tuners or transmatches or matching networks are not necessary. Tuners have a small amount of loss. They encourage guys to transmit into antennas that are not way off in frequency. As a result, in some cases, more than half of the signal is lost in the system. tuners can just make it worse. I ran QRO power into my yagi and never used a tuner. Design and build the antenna system so that it works without having to invoke some box to make the transceiver happy. I did work every country in the world over 50 years Tuners should be a very last resort...and not a good one. Did that help or answer your question? 73, Jim W6LG On Fri, Sep 11, 2020 at 5:10 PM KZbin wrote:

[@rentacowisgoogle]

If I wanted to make a VHF J-Pole to put way up in a tree and connect it to my scanner, could I use any old coax and still get good reception? I've got a bunch of satellite TV coax RG6, but I don't know the velocity factor for the calculator i'm using.

[@ham-radio]

You can go to a table or list that will show the loss of RG6. In round numbers, you will lose 60% with 100 feet in the coax. 73, Jim

[@rentacowisgoogle]

@@ham-radio Thanks Jim! I'll try to find some data sheets for the stuff I'm using to find the exact numbers, but ~60% seems like a good place to start. I'll let you know how the reception is! 73

[@eekmeout]

Do you miss Wolf Mountain?

[@ham-radio]

I do! I really do. There is a ton of noise here and the ground, topography is relatively flat. But at least I am now on the air; QRV. Thanks! 73, Jim

[@bobrunge7594]

What the heck is KZbin Elmer? I get this on your video titles. Bob Runge W1LSZ