There are reasons why you may want half or full wave lengths/multiples. For one, you can look at the antenna's complex impedance at the shack end. Secondly, the system will ignore the impedance of the feedline. Did you learn anything today?
You know I have watch a lot of these videos and this one is the best so far! Thank you…I see lots of people saying it don’t matter…But have seen no evidence of that… not one video or article show the proof it don’t matter! And the truth is it never will to them! For me I don’t see the harm in doing what you are talking about…. I’m always learning and looking for ways to improve on my radio system! What you are saying makes perfect sense and in radio world everything matters if you want the best it can be!
I think I should make a video to disprove all this is not necessary, C.B.'ers say it is, amateurs say no it isn't. In 49 years I have not cut coax to a precise length except for phasing purposes on crossed dipoles or a 4:1 balun on my home made 5 element Yagi on 2m. Cutting cable to precise lengths to the aerial and coax jumper lead. What about taking the length of the SWR meter into account? That's in circuit as well, you know. Did you allow for that? And is it on the aerial side or the transmitter side? Neither, because it all adds up to one length of coax! An SWR meter doesn't magically isolate one side from the other. I've got everything set up IF my camera has enough memory to cope as it was my Dad's and quite old. Any length of coax required to reach the aerial is all that is needed. G4GHB.
I am looking forward on your video. Matching impedance at 200ohm balance the line is different topics FYI. Please send me the link once your video is up! 73 Peter
@@Mr.Amplifier. Last year I made the mistake of getting a new card for my camera and it didn't work so I'll have to find a source for the old type card.
RG400 50 ohm with a Velocity of 69.5 low loss Teflon insulation Trippel shelled, good up to 12.4 GHz At 1GHz it can handle 600 watts. Also on the Ham frequencies it can handle 1,000 Watts and more. a little smaller than RG58. Its used in all kinds of aviation equipment private and military. Highly heat resistance, you can put on your connector with out melting the insulation. One caveat it's a little pricey not to bad though. Amazon no name 40ft about 70ish dollars, it goes for a lot more at other places. I love this stuff, great feed line coax cable and jumpers between equip..
Unless you are using it as a tuning stub Coax should be of a length that is not resonant on your frequency or any harmonic there of A resonant coax becomes part of the antenna and radiates That is bad
@@robertbobbitt8448 your coax is part of your antenna system. For a mono band only should be electrical length over frequency! to maintain 0v on your coax.
Great video but as you pointed out this seems to make sense if you tune (adjust the antenna length) the antenna without the coax to a zero reactance alone then you need to get the coax to be a zero reactance also. I’m wondering if you take a random length of coax attach it to the antenna and then adjust the antenna length for best SWR/reactance are you getting the same benefit?
Most people use a random lengths of coax and tune the antenna, in many cases I seeing where people need more whip on the mobile tuning for the same reason. However, I start my setup base on the type of antenna I am going to be use and considering the angle of radiation,I start doing my calculations from there, every antenna is different waveform or radiation. I have made a video in Spanish where I explain the angle of radiation depending on the degree of the wavelength… all our measurement should start at the antenna.
when you have a 100' of coax do you just cut is 1/2 wavelength added togather and odd multiples like 3,5,7,9, odd wavelengths and how do you test for rhis using rigexpert AA 55 zoom
Having a home installation the idea is to keep your wavelength as near is your antenna wavelength as well. For a mobile application or Cb most use a 1/4wave. For a home installation if is a mono-band antenna is fine to follow the equations, once you use a multi-band antenna everything is compromise. Your wavelength should be an múltiples of 1/4, 1/2, 3/4, 1, 5/4 an múltiples once you dived by speed of light and the frequency. Then you moved to velocity factor of your coax as I described on the video. I hope this is helpful to you! Best regards Peter.
So I’m using the rig expert aa35 it definitely has less features but on my 60ft run of coax ( lmr400 ) which has a 1/4 wave of 7.59ft) this is going to an a99 what im seeing in all parameters is Swr-18 RL .96db (Z) 91.7 ohm phase -57° R 12.0 X -90.9 this is all at 27.200 the run is roughly 60ft and is showing resonance at 27.304 I’m having a hard time understanding this something doesn’t seem right I did leave myself extra cable to trim but not sure if that’s going to help? Should I try to get it down to 54 feet ? Or am I way off target here lol? I’ll also be adding some jumpers for amp and potentially driver amp on occasion. Unfortunately that a99 isn’t getting tuned perfectly to 11meter seems it likes the higher end of 11 meter so I may replace it. It’s mounted to a vent pipe on my roof about 25ft but only about 2ft off the roofline in the center no trees or anything nearby so maybe I can try raising it but don’t think that’s gonna help the swr much, raising and lowering it a couple feet had no impact.
Hi Christian, when you set up the base station is different depending on the type of antenna that you are using. In your case you are using a 1/2 wave antenna. I will recommend you to watch a video in Spanish that I did few years ago. The cover is a paper looking from the top. just use translation and make sure you have pen and paper I done intense coverage on selecting antenna and how to make your length from the antenna to you radio.. the topics I cover are angle of radiation of verticals antennas, how to obtain the best system from electrical length over frequency. I think it will be useful for you. 73 Peter
@@Mr.Amplifier. thanks for the response, what’s the title of the video? I can’t seem to find it. Also, I’m in the process of placing an order I was thinking lmr240 UF for jumpers you think that’d be okay? Most that will be ran through it is 1kw
So you are cutting the coax for 1/4 wave length? If I remember right. If doing half wave length, the cut end has to be shorted according to RigExpert directions. 1/4 wave length does not have to be shorted.
Correct doesn’t have to be shorted. You can cut 2/3 or 1/3 of wavelength is when needs to be shorted. (I believed) The formula will be different for 1/3 I like doing it 1/4 or 3/4 or even 1/2 sometimes depending on the application.. 73
I believe you can use a T connector, one side with a 50 ohm dummy load, the other side you connect the coax for trimming to get your 1/2 wavelength. How do you tune the antenna before adding the coax??
I use the T connection to tune a 75ohm coax into a 50 ohm impedance antenna. Having a 50 ohm load on the T connection is also a great way to get your measurements
Coax lenth dont matter if it does you have something else wrong. You use what it takes to run from antenna to radio.
There are reasons why you may want half or full wave lengths/multiples. For one, you can look at the antenna's complex impedance at the shack end. Secondly, the system will ignore the impedance of the feedline. Did you learn anything today?
@jamesvw769 is not about the impedance is about electrical length over frequency.
It is plenty of literature out there..
You know I have watch a lot of these videos and this one is the best so far! Thank you…I see lots of people saying it don’t matter…But have seen no evidence of that… not one video or article show the proof it don’t matter! And the truth is it never will to them! For me I don’t see the harm in doing what you are talking about…. I’m always learning and looking for ways to improve on my radio system! What you are saying makes perfect sense and in radio world everything matters if you want the best it can be!
It’s all about understanding the electrical length over frequency..
73
Peter.
Thank you for the English version.
I think I should make a video to disprove all this is not necessary, C.B.'ers say it is, amateurs say no it isn't. In 49 years I have not cut coax to a precise length except for phasing purposes on crossed dipoles or a 4:1 balun on my home made 5 element Yagi on 2m.
Cutting cable to precise lengths to the aerial and coax jumper lead. What about taking the length of the SWR meter into account? That's in circuit as well, you know. Did you allow for that? And is it on the aerial side or the transmitter side? Neither, because it all adds up to one length of coax! An SWR meter doesn't magically isolate one side from the other.
I've got everything set up IF my camera has enough memory to cope as it was my Dad's and quite old.
Any length of coax required to reach the aerial is all that is needed.
G4GHB.
I am looking forward on your video.
Matching impedance at 200ohm balance the line is different topics FYI.
Please send me the link once your video is up!
73
Peter
@@Mr.Amplifier. Last year I made the mistake of getting a new card for my camera and it didn't work so I'll have to find a source for the old type card.
RG400 50 ohm with a Velocity of 69.5 low loss Teflon insulation Trippel shelled, good up to 12.4 GHz At 1GHz it can handle 600 watts. Also on the Ham frequencies it can handle 1,000 Watts and more. a little smaller than RG58. Its used in all kinds of aviation equipment private and military. Highly heat resistance, you can put on your connector with out melting the insulation. One caveat it's a little pricey not to bad though. Amazon no name 40ft about 70ish dollars, it goes for a lot more at other places. I love this stuff, great feed line coax cable and jumpers between equip..
Great help I have a nano vna smith chart going to play around with some old coax
Great video. Thx
Unless you are using it as a tuning stub Coax should be of a length that is not resonant on your frequency or any harmonic there of A resonant coax becomes part of the antenna and radiates That is bad
@@robertbobbitt8448 your coax is part of your antenna system. For a mono band only should be electrical length over frequency! to maintain 0v on your coax.
Thank you. Perfect explanation
Have to consider connector lengths? (Pl259, N, etc.)
Great info, thank you
Great video but as you pointed out this seems to make sense if you tune (adjust the antenna length) the antenna without the coax to a zero reactance alone then you need to get the coax to be a zero reactance also. I’m wondering if you take a random length of coax attach it to the antenna and then adjust the antenna length for best SWR/reactance are you getting the same benefit?
Most people use a random lengths of coax and tune the antenna, in many cases I seeing where people need more whip on the mobile tuning for the same reason. However, I start my setup base on the type of antenna I am going to be use and considering the angle of radiation,I start doing my calculations from there, every antenna is different waveform or radiation. I have made a video in Spanish where I explain the angle of radiation depending on the degree of the wavelength… all our measurement should start at the antenna.
sir please enlighten the same result with VNA
when you have a 100' of coax do you just cut is 1/2 wavelength added togather and odd multiples like 3,5,7,9, odd wavelengths and how do you test for rhis using rigexpert AA 55 zoom
Having a home installation the idea is to keep your wavelength as near is your antenna wavelength as well. For a mobile application or Cb most use a 1/4wave.
For a home installation if is a mono-band antenna is fine to follow the equations, once you use a multi-band antenna everything is compromise.
Your wavelength should be an múltiples of 1/4, 1/2, 3/4, 1, 5/4 an múltiples once you dived by speed of light and the frequency. Then you moved to velocity factor of your coax as I described on the video. I hope this is helpful to you!
Best regards
Peter.
What was the phase deg what are you striving for ? i like to get close to even number or close to 90,180 etc .
90° yes keeping your coax within 0 voltage is near perfect!
So I’m using the rig expert aa35 it definitely has less features but on my 60ft run of coax ( lmr400 ) which has a 1/4 wave of 7.59ft) this is going to an a99 what im seeing in all parameters is
Swr-18 RL .96db
(Z) 91.7 ohm phase -57°
R 12.0 X -90.9 this is all at 27.200 the run is roughly 60ft and is showing resonance at 27.304
I’m having a hard time understanding this something doesn’t seem right I did leave myself extra cable to trim but not sure if that’s going to help? Should I try to get it down to 54 feet ? Or am I way off target here lol? I’ll also be adding some jumpers for amp and potentially driver amp on occasion. Unfortunately that a99 isn’t getting tuned perfectly to 11meter seems it likes the higher end of 11 meter so I may replace it. It’s mounted to a vent pipe on my roof about 25ft but only about 2ft off the roofline in the center no trees or anything nearby so maybe I can try raising it but don’t think that’s gonna help the swr much, raising and lowering it a couple feet had no impact.
Hi Christian, when you set up the base station is different depending on the type of antenna that you are using. In your case you are using a 1/2 wave antenna.
I will recommend you to watch a video in Spanish that I did few years ago. The cover is a paper looking from the top.
just use translation and make sure you have pen and paper I done intense coverage on selecting antenna and how to make your length from the antenna to you radio.. the topics I cover are angle of radiation of verticals antennas, how to obtain the best system from electrical length over frequency. I think it will be useful for you.
73
Peter
@@Mr.Amplifier. thanks for the response, what’s the title of the video? I can’t seem to find it. Also, I’m in the process of placing an order I was thinking lmr240 UF for jumpers you think that’d be okay? Most that will be ran through it is 1kw
@@ChristiannTyler
Como sacar las medidas para el coaxial de tu antena para la estación de tu radio.
Copy and paste..
@@Mr.Amplifier. unfortunately I can’t get it to translate do you have any other places I might be able to find this information?
that new rig expert actually has more features than the older rig expert in video.
So you are cutting the coax for 1/4 wave length? If I remember right. If doing half wave length, the cut end has to be shorted according to RigExpert directions. 1/4 wave length does not have to be shorted.
Correct doesn’t have to be shorted. You can cut 2/3 or 1/3 of wavelength is when needs to be shorted. (I believed) The formula will be different for 1/3 I like doing it 1/4 or 3/4 or even 1/2 sometimes depending on the application..
73
Swr.. Standing Wave Ratio.
I believe you can use a T connector, one side with a 50 ohm dummy load, the other side you connect the coax for trimming to get your 1/2 wavelength. How do you tune the antenna before adding the coax??
I use the T connection to tune a 75ohm coax into a 50 ohm impedance antenna. Having a 50 ohm load on the T connection is also a great way to get your measurements
@@Mr.Amplifier. thank you for all you do, I learn so much from your videos. So, how do you tune an antenna for 1000 watts before using your coax??
(V)SWR
(Voltage) Standing Wave Ratio
What about it ?
You had trouble remembering what each letter stands for...
👍
X=0 🤘
There is a.much better wayy friend
Half wavelength man !!!!
Even 2/3 will do. Thanks