Jim, thanks for the content you post. It is extremely helpful. I remember our QSO one afternoon where you helped me with the settings on my ICOM 7300. I have never changed those settings after that QSO. I consistently get reports of "great audio" or "beautiful audio" by other radio operators, especially during Parks on the Air activations. I always tell them you were the one who helped make the adjustments. We had spoke briefly once after that during one of the activations and you had asked what the allure of POTA was. Again, thanks for all of your informative content. Best wishes, AI5NQ
Just a great explanation! I recent met a guy who wasn't sure about getting his ham license because he wasn't sure about all the details concerning setting up antennas and the rules of the radio. I broke it down for him based on my experience. I just made a simple dipole with a coiled coax rf choke (which got my family to call it my cantenna) and adjustable ends to tweak the swr. Antennas like this aren't super good performers compared to beams, but they can and do make the radio happy so you can throw out a signal. You can only go up from there! I'm thinking about building a semi-permanent beam using paracord and copper wire. There is no end to the fun you can have with antennas. Thanks for your videos Jim. They are always informative.
Found this very informative, never even considered the test you conducted. Funny, I just replaced some lmr400 with rg393 and swr went up by .2 now it makes sense. 😊
Clear and concise with practical example- always enjoy. However, the VF should not come into play. While that does affect where the peaks and minimums occur on the line, the SWR is independent of that. Some meters that don’t make a proper measurement may be affected by that, but not the actual SWR.
The topic of SWR and a lossy coax was one of the things the technician test covered. I knew the correct answer, but not the why behind it. Thanks Jim for finally clearing that up for me. 73 de KN6VMK
New subscriber and ham. Thanks to you I’ve made fewer mistakes. My first antenna was a discone. Took your advice and bought lmr400 for it. Just put up my first end fed and used the lmr400 and ran rg8x for the discone. Using a nanovna proves your advice to use the best cable you can afford. Thanks.
I was really proud that my first antenna that I built had great SWR across the 20m band for my privileges. I came to realize later that my cheap coax had a lot to do with it. I would be interested to see a real life comparison between the RG8x and LMR400 and the impact on signal strength from the same antenna with the same power on 10 meters, similar to your video on the impact of power that you did not too long ago. I notice that my received signal reports are typically much better than my sent signal reports on the higher bands. I am using 100’ of RG8x with a 80m off center fed dipole with the feed point at about 35’. Thanks for the video and 73.
Hi Jim, always nice to watch one of your videos........my understanding on what's going on......... Lets say you are putting out 100 watts at the Tx. for simplicity lets say your coax yields 3db of loss so you only have 50 watts at the antenna. Lets say you have a very bad match up there and have 10 watts of reflected power but by the time it gets back to the SWR bridge its only 5 watts (same 3db loss). The meter does its "calculation" using the original 100 watts(all it knows) but only has 5 watts of reflected power to work with so the ratio between forward & reflected power looks a lot better (100:5) there than at the antenna where its 50:10 watts. Only fictional "lossless" coax will yield the same number at both ends of the run. The better the cable the closer you get to the same number at both ends. the way I see it anyway..............be well and enjoy Thanksgiving......73 Mike, K1FNX near Boston
Twice the line loss must be considered, going to the antenna and returning from the antenna. VNA's have a Return Loss scale in Db to make measurements of complex antenna systems easier, a 24Db RL minus 1Db line loss times two equals a 22Db RL about 1.2VSWR at the antenna terminals. Demo, a 10Db pad will read a 20Db RL on a VNA and about a 1.3 on a VSWR meter.
Great video Jim as always very informative. Heard you on the air a couple times and was going to try and call you but you were going qrt both times. Hopefully I’ll get to work you at some point. Happy holidays! 73 KB8NEV Rick.
Nice demonstration. It would be interesting to see what the results would be if the SWR meter was located at the distant (load) end of the cable(s). - 73 WC8J
Of course, this begs the question of now that “we” can see that our antenna is working less well than we hoped (and hope is not a plan), what do we do about the antenna ? The “system” question.
Great demo .The loss in coax can hide the actual SWR at the antenna . If taking a outher measurement at the antenna side you will see how a lossy coax can hide the SWR . And better coax will show more true number . Best to tune antenna buy measuring SWR at the antenna . Then if SWR really jumps up then you know you need better coax. You can test coax with a 50 ohm dummy load. then use a 75 ohm load and compare the two. I find a lot of that RG8X sold today ,not so good at all. ABR /DX Engineering / M & P have good versions of RG 8X . But will cost some $$ . A bunch of that RG 8X sold on Amazon and eBay is very lossy and poor quality . Just a waste of money ! I start with buying my coax from a good known source then pick the type and length and ends I want. I bet after re tunning the antenna with LMR 400 it will work a lot better ! 73
Aha! I was thinking only about the effects of the outer shield and the different lengths, but hadn’t considered that SWR measurement relies on the reflected signal and the loss it experiences in the cable. So this is why measuring measurements should be done at the feed point, correct?
Assuming both the RG8X and LMR400 are of reasonable-quality manufacture, if the two types are compared in on-the-air tests, then no difference, or at most an insignificant difference, will be noted on the HF bands. On the other hand, if something goes wrong with the antenna, the RG8X will provide a bit more protection to the transmitter as compared to the LMR400. So which is better? If you feel good having spent more money on LMR400, then okay, but please don't ever make someone who is using RG8X feel bad about their choice.
Curiosity.. what's the 2 boxes behind you on top of with red light on. Fellow ham shacks are always interesting to me. And also very interesting about coax. I never would have though so.
Hello, I would not think that this difference would be significant. 1:3 vs 1:7 at 14Mhz. I would be curious to know if this difference would be the same on the other HF bands, 7, 21 & 28. Let me presume that the difference would be less noticeable at 7 Mhz vs 28Mhz.
RG8/RG11 has nearly the same attenuation loss than LMR400. I changed my coax from one to another a few time ago... No difference at all...(VHf, 2 meter band)
Question: why do HAMs do CW with a code with short and long tones? Why not two different frequencies. I was at an ARRL meeting and K6CTW told me if you use two different frequencies, then your transmission rate can increase 10 to 15 percent.
Using 2 (or more) frequencies is called FSK, frequency shift keying. That's what most other digital modes use in some form or other. Listen to RTTY sometime. There are two tones, Mark and Space. CW only requires one oscillator for the one tone.
In a nutshell yes. VSWR is a ratio of power transmitted to power reflected. With the lower loss coax cable more of the transmitted power makes it to the load (the antenna) and if there is a mismatch at the load some of that power is reflected back to the transmitter. More of the reflected power makes it back to the transmitter with the lower loss coax cable which causes the measured VSWR to increase. The VSWR of the load never changed. What changed was that the lower loss coax cable increased the accuracy of the VSWR measurement because more of the reflected power made it back to the meter and less of it was burned up as heat in the coax. Mike KC3OSD
@ham-radio What should perhaps be mentioned or recommended in general in this context is the purchase of a (nano) VNA. And in the application, the calibration of the coaxial cable used. Then there is no longer any doubt and you get clarity about the actual conditions at the feed point. In most cases, the money would also be much better invested in the long term than in more expensive coaxial cable.
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Thanks, Jim. Good to see you.
Jim, thanks for the content you post. It is extremely helpful. I remember our QSO one afternoon where you helped me with the settings on my ICOM 7300. I have never changed those settings after that QSO. I consistently get reports of "great audio" or "beautiful audio" by other radio operators, especially during Parks on the Air activations. I always tell them you were the one who helped make the adjustments. We had spoke briefly once after that during one of the activations and you had asked what the allure of POTA was. Again, thanks for all of your informative content. Best wishes, AI5NQ
Radio is wonderful pastime because we can take it as far as we want and there is always more to learn.
Good to see you Jim and keep safe. 73
Just a great explanation! I recent met a guy who wasn't sure about getting his ham license because he wasn't sure about all the details concerning setting up antennas and the rules of the radio. I broke it down for him based on my experience. I just made a simple dipole with a coiled coax rf choke (which got my family to call it my cantenna) and adjustable ends to tweak the swr. Antennas like this aren't super good performers compared to beams, but they can and do make the radio happy so you can throw out a signal. You can only go up from there! I'm thinking about building a semi-permanent beam using paracord and copper wire. There is no end to the fun you can have with antennas. Thanks for your videos Jim. They are always informative.
Found this very informative, never even considered the test you conducted. Funny, I just replaced some lmr400 with rg393 and swr went up by .2 now it makes sense. 😊
Congratulations on reaching 50.1K subscribers, l know this was a milestone you wished to reach.🎙️
Glad to see another video from you!
Great work as always, Jim. Thank you!
Thanks for the reminder about how coax loss affects SWR. Good to see you on a new video.
Great insight Jim. 73 KK3R Houston, Tx
Great sharing Jim. Take care. God bless you
Always learning from you as a new General ticket holder! I wish you and your family a wonderful Thanksgiving! All the best 73’s!
Clear and concise with practical example- always enjoy. However, the VF should not come into play. While that does affect where the peaks and minimums occur on the line, the SWR is independent of that. Some meters that don’t make a proper measurement may be affected by that, but not the actual SWR.
Excellent video I always learn something from them, Thanks!
Ah, that's fun.
"My antenna has been up there for 20 years and the SWR is getting better."
Well....
Glad I saw this. I've always thought the 'larger' the coax, the less resistance. But as a newbie ham, what I think rarely coincides with fact . . . 😉
What an absolutely fantastic explanation. Thank you so much for making videos like this.
Great explanation and so good to see you Jim! 73 AA7MO
Hi Jim.
Always enjoy your teaching
73
Thank you Jim. Good to see you. Ai6lz
Great explanation! Makes complete sense, and good to see you. 73 KC2GRN
The topic of SWR and a lossy coax was one of the things the technician test covered. I knew the correct answer, but not the why behind it. Thanks Jim for finally clearing that up for me. 73 de KN6VMK
Great demo Jim. Thanks!
New subscriber and ham. Thanks to you I’ve made fewer mistakes. My first antenna was a discone. Took your advice and bought lmr400 for it. Just put up my first end fed and used the lmr400 and ran rg8x for the discone. Using a nanovna proves your advice to use the best cable you can afford. Thanks.
I was really proud that my first antenna that I built had great SWR across the 20m band for my privileges. I came to realize later that my cheap coax had a lot to do with it.
I would be interested to see a real life comparison between the RG8x and LMR400 and the impact on signal strength from the same antenna with the same power on 10 meters, similar to your video on the impact of power that you did not too long ago.
I notice that my received signal reports are typically much better than my sent signal reports on the higher bands. I am using 100’ of RG8x with a 80m off center fed dipole with the feed point at about 35’.
Thanks for the video and 73.
That's exactly what I was assuming !
Good to see these videos keep coming Jim - keep safe. Tim.
Thanks Jim❤
When I read the video title, that was my guess as to why the 8X showed lower SWR. 73, Jim K6KCP across the river from you here in West Sac.
Thank you so much for the video!
Hi Jim, always nice to watch one of your videos........my understanding on what's going on......... Lets say you are putting out 100 watts at the Tx. for simplicity lets say your coax yields 3db of loss so you only have 50 watts at the antenna. Lets say you have a very bad match up there and have 10 watts of reflected power but by the time it gets back to the SWR bridge its only 5 watts (same 3db loss). The meter does its "calculation" using the original 100 watts(all it knows) but only has 5 watts of reflected power to work with so the ratio between forward & reflected power looks a lot better (100:5) there than at the antenna where its 50:10 watts. Only fictional "lossless" coax will yield the same number at both ends of the run. The better the cable the closer you get to the same number at both ends. the way I see it anyway..............be well and enjoy Thanksgiving......73 Mike, K1FNX near Boston
Thanks Jim
tks Rockland River....🙋
Hi, Jim. Again, an excellent video and explanation. You always amaze me. 73 Alan KZ6B
Thanks, Jim, as always. We wish you
good health and a very Happy
Thanksgiving.
73 de W2CH Ray and KC2NKU Marylyn. 😅
Nice...
Thank you sir...
Twice the line loss must be considered, going to the antenna and returning from the antenna. VNA's have a Return Loss scale in Db to make measurements of complex antenna systems easier, a 24Db RL minus 1Db line loss times two equals a 22Db RL about 1.2VSWR at the antenna terminals. Demo, a 10Db pad will read a 20Db RL on a VNA and about a 1.3 on a VSWR meter.
Thanks for another great video!!
Great video Jim as always very informative. Heard you on the air a couple times and was going to try and call you but you were going qrt both times. Hopefully I’ll get to work you at some point. Happy holidays! 73 KB8NEV Rick.
Nice demonstration. It would be interesting to see what the results would be if the SWR meter was located at the distant (load) end of the cable(s). - 73 WC8J
Pahh, no mystery. I had this sussed!
Of course, this begs the question of now that “we” can see that our antenna is working less well than we hoped (and hope is not a plan), what do we do about the antenna ? The “system” question.
Very interesting situation well explained. 73
Jim it went higher because more power was reaching the antenna and more being returned.
Great demo .The loss in coax can hide the actual SWR at the antenna . If taking a outher measurement at the antenna side you will see how a lossy coax can hide the SWR . And better coax will show more true number . Best to tune antenna buy measuring SWR at the antenna . Then if SWR really jumps up then you know you need better coax. You can test coax with a 50 ohm dummy load. then use a 75 ohm load and compare the two. I find a lot of that RG8X sold today ,not so good at all. ABR /DX Engineering / M & P have good versions of RG 8X . But will cost some $$ . A bunch of that RG 8X sold on Amazon and eBay is very lossy and poor quality . Just a waste of money ! I start with buying my coax from a good known source then pick the type and length and ends I want. I bet after re tunning the antenna with LMR 400 it will work a lot better ! 73
Also, the feedline is acting like an impedance transformer at anything except a perfect SWR .
I use the new Bluetooth coax cable. SWR is not an issue.
Aha! I was thinking only about the effects of the outer shield and the different lengths, but hadn’t considered that SWR measurement relies on the reflected signal and the loss it experiences in the cable. So this is why measuring measurements should be done at the feed point, correct?
That’s why I measure SWR at the antenna.
Assuming both the RG8X and LMR400 are of reasonable-quality manufacture, if the two types are compared in on-the-air tests, then no difference, or at most an insignificant difference, will be noted on the HF bands. On the other hand, if something goes wrong with the antenna, the RG8X will provide a bit more protection to the transmitter as compared to the LMR400. So which is better? If you feel good having spent more money on LMR400, then okay, but please don't ever make someone who is using RG8X feel bad about their choice.
Different line loss in the cable would explain change in SWR.
Curiosity.. what's the 2 boxes behind you on top of with red light on. Fellow ham shacks are always interesting to me. And also very interesting about coax. I never would have though so.
Add a choke at antenna and do the test again !
So we should just use old Radio Shack coax and be happy with the numbers. Ha!
So am i expecting the similar response changing from g8x to g213?? I just boughht 200' 213 for 2 runs replacing my smaller lines
Phase angle and volocity
Thank you, Jim. Have a great day, anyway. N0QFT Glen
the answer at 3:25
Hello, I would not think that this difference would be significant. 1:3 vs 1:7 at 14Mhz. I would be curious to know if this difference would be the same on the other HF bands, 7, 21 & 28. Let me presume that the difference would be less noticeable at 7 Mhz vs 28Mhz.
greater return loss on the RG8x
So if SWR changes with the wire used in the feedline, how can you ever trust any SWR value?
👌👍👏
RG8/RG11 has nearly the same attenuation loss than LMR400. I changed my coax from one to another a few time ago...
No difference at all...(VHf, 2 meter band)
Simple haven't watched. But less loss will show a higher swr unless you have a perfect match. Now i will see what you say.
What would one do to offset the SWR
Question: why do HAMs do CW with a code with short and long tones? Why not two different frequencies. I was at an ARRL meeting and K6CTW told me if you use two different frequencies, then your transmission rate can increase 10 to 15 percent.
Using 2 (or more) frequencies is called FSK, frequency shift keying. That's what most other digital modes use in some form or other. Listen to RTTY sometime. There are two tones, Mark and Space. CW only requires one oscillator for the one tone.
✌️🇺🇸🙏
So a higher SWR reading means less of a loss???? 🤔
Bob Runge
W1LSZ
I don't think you used enough question marks.
In a nutshell yes. VSWR is a ratio of power transmitted to power reflected. With the lower loss coax cable more of the transmitted power makes it to the load (the antenna) and if there is a mismatch at the load some of that power is reflected back to the transmitter. More of the reflected power makes it back to the transmitter with the lower loss coax cable which causes the measured VSWR to increase. The VSWR of the load never changed. What changed was that the lower loss coax cable increased the accuracy of the VSWR measurement because more of the reflected power made it back to the meter and less of it was burned up as heat in the coax. Mike KC3OSD
@@mikesradiorepair Thank you Mike… appreciate your reply.
@mikesradiorepair also with lower loss feedline more of the reflected power will reflect back from transmitter back to antenna
Old trick use lossier cable to lower swr at radio.
😇73
losses, losses, losses.....
Yes, yes and yes. 73, Jim W6LG
@ham-radio What should perhaps be mentioned or recommended in general in this context is the purchase of a (nano) VNA. And in the application, the calibration of the coaxial cable used. Then there is no longer any doubt and you get clarity about the actual conditions at the feed point. In most cases, the money would also be much better invested in the long term than in more expensive coaxial cable.
I need a girlfreng 😢
Thanks Jim