Thanks Jim for this great video! I just purchased by first SWR meter to check my dual band antenna performance and was amazed to see that 100 watts of my FTM-200 was only showing 47 on the meter (with 1.34 SWR). Your video was perfect in explaining what I was seeing and why. I am still learning (studying for general) but this really helped. Thanks and hope you are doing well. Take care. KN6HUV.
Jim, I'm newly minted; just hit the database last week. Been running through your library the last 2-3 weeks though and some of the topics stick and some of it sails over my head but I know exactly where to come to in the future for clear explanations and good info. Can I say sir, your production is amazing, and I sincerely appreciate you taking the time to share. THANK YOU for this service you are providing. -J
Wow, that is very kind and generous. Thank you Josh. I am working on the second episode of setting up a station for HF now. If you look closely you can see the "green screen" I experimented with in the first episode. It is fun to do. The stuff that goes over you head now won't as you learn. Ask when you don't understand. Most hams will spend time explaining how things work. We all want you to be successful and enjoy this radio service. 73, Jim W6LG
Hi: Jim, Paul here, 67 and now retired. I'm finally doing something I have always wanted to do and that's getting into ham radio. Now studying for my ham license and came across your so grounded and awesome videos Mate. I was trained as an Electrical Power Systems Engineering Technologist here in Ontario Canada. You remind me of some of the awesome wise men who trained me in my field of things I will never forget. Mentors like you are full of great down to earth life experiences in ham radio and for that sir, I most humbly salute you. I have subscribed to your channel and with time permitting will review ever video you have made. God Bless Jim and long life to you my new ham radio mentor. "Huge 73's to you mate" PS: "Merry Christmas To You And Yours"
Hi Paul, Wow! Thanks for the very kind and generous words. I'll try to live up to that in future videos. The true story is that I had two neighbors when I was licensed in the early 1960's who spent time with me explaining things (like SWR) in a way that young teenager could understand. One of those guys was a friend for more than 30 years. He was a skilled operator and a good example. So I am trying to pass that a long to others. Also when I was a teenager there was a guy who had a TV show called Mr. Wizard. e would do an experiment and then explain why things happened. So I try to do a little of Mr. Wizard when I can as a part of the explanation. To All: I have been working every day for several hours since August 26 to get a radio room/RU-vid room ready for videos. I still have one wall left to finish the tape and texture stage of the drywall installation. So I plan to produce a video very soon. After that, the room will be staged so that I will be able to do videos quickly. In that room will be a video editing desk with 2 new computers that have I built recently that have fast processors and fast video cards running a new to me video editing program. Paul thanks again. And may I make a little correction to 73. That is a number from a chart or a list of messages. So a telegrapher could take a message and break it down into a list of numbers and not have to send the entire message. It might have been some like: Dear Louise 33 15 88 Bill. There was an end of message tag that I don't remember. So, it is just 73 and not 73's possessive. No big deal but something most guy may not know. In any case have lots of fun. 73, Jim
I first watched one of Jim's videos and then wandered off into the noise, eventually bounced off the ionosphere and made my way back here. Top notch advice professionally delivered every time.
Jim, I'm late to this one, but thank you very much for this! I'm new and just getting my first station together. You have now helped me avoid a mistake I was about to make! Really enjoy all of your informative videos. Great, relaxed teaching style.
Wow, this is eye opening! Thank you very much! I've been in the game for a few months and though "75 ohm line, RG8, no difference, just a marketing thing". This is huge, 50% losses and a faulty SWR reading. This video and the one on feed line loss have been 2 of the most helpful videos I've seen so far. Great work! Thanks again. 73 KE8EAS.
I'm studying for my extra class and figured I would take a break. I really enjoy the knowledge that I gain from watching your videos. I'm very new to ham radio and really glad you share your years of knowledge. Thank you and 73. KD9GJX
Excellent video. I'm new to Ham, but I'm a truck driver and I've used 11 meter CB for years. I had a CB shop technician tell me to just use a 21 foot feed line and I would never have to worry about the SWR. Lol. Now we know why that makes the SWR look so low.
Thanks for sharing. Find a local ham who has decades of experience and maybe is an engineer. Local guys are usually very happy to provide help to someone who is just starting out. If there is a subject for a video that you would like to see, please let me know via email. 73, Jim
I am just building my "shack". it is on a small lot, but has a metal carport grounded 30 inches into the soil 6 times right outside my radio room. the antenna I am going to use for my Kenwood TS520S is going to be a random wire antenna with a feed point at the carport and a pole to let me reach the roof level. from there, I am going to use standoffs to raise it above the roof and carry it in a mild zigzag to my shed, if needed. I want to use 160M and am an early riser, all the HF bands interest me, and I will be exploring them all over time. My radio goes from 160m to 10m, I may use a vertical for 10M. I enjoy your way of explaining things, and look forward to more videos.
Hi Jim! For the energy to be re-reflected from the transmitter back toward the antenna requires a reactive element to catch it and then release it in the proper phase. An antenna tuner is such a device, but there was none in your drawing. As to your main point, yes, a lossy feedline will certainly make the SWR look a lot better at the output of the tuner than it really is at the antenna. Nice graphics, BTW!
Thanks Dave. How's it going with you? it is a beautiful day here and warm. I was in the backyard hanging an OCF dipole. Some local guys have offered to come by here and help me add 15 meter elements to my homebrew 3 element 20 meter monoband Yagi. At this time I am planning on 2 feedlines. I am using a beta "hairpin" match now. Nice to hear from you again David. 73, Jim W6LG now in Rocklin CA
Thank you so much for walking through this. The math is not difficult and so many documents fail to show how important feed loss is. The exams allude to the potential impact of feed line loss on SWR, but none of the manuals (that I've seen so far) provide a computational approach to accounting for all of the RF energy. It occurs to me that going through the arithmetic to account for all the RF energy leaving the transmitter is an excellent mechanic for understanding how much power is getting out of the antenna... and for spending appropriate resources on reducing loss between the transmitter and the antenna. Therefore, I got a big take-away from your video that I will apply as I design my station. (I take the tests mid-March -- at least technician and general... studying the extra manual now.) Excellent... thank you. Would you please post your website in the description of your videos or put it in the about section of your YT channel, please? I can understand not wanting to publish an email address, but I would email you if I had it.
Good video. I don't get too worked up about SWR. I use good feedline such as LMR400 for VHF+ . I do check and record the SWR and other parameters and close enough is good enough. I'd rather be operating than worrying about getting 1:4 SWR down to 1:1. I have known people who agonise about such things. I'm also recovering and with time on my hands have been enjoying your videos. Lots of good information and I like how you present it in an easy going manner. Best of luck with your health.
Most don't look at the line lose. There is another thing I have seen and that is where you read the SWR. In the VHF range moving the meter inches can give different readings. Where is the meter along the wavelength. I have worked on radios for years, not ham. Found that where the meter is can change what the meter reads. With a 6 inch cable from the radio to the meter will read one thing and a 12 cable you can get another reading. I think a high SWR is only good to keep the ice from forming on the coax. With the exception you gave on here where about half the 100 watts is lost in the cable, about 60 watts is given in heat in the cable to keep the ice off of it!
This is correct. The only time you're going to achieve the same reading anywhere along the feed line is when the antenna impedance is the same as the radio (and the characteristic impedance of the feed line for a random length), and that's the conundrum... and it would be 1:1 anyway. Right? So this means you need to know the impedance of the antenna. This measured right at the feedpoint or via a half wavelength (taking in the VF) or multiples thereof. Furthermore, the impedance of the coax in this instance doesn't really matter. So know the antenna is right for single band use and the rest will take care of itself. I might add that if the SWR doesn't change with the length of the line, then this would indicate the load impedance is correct. I still feel like I'm going round in circles though.
Jim, thank you for your video. I watched this video moments ago and it was extremely informative. I didn't consider (for whatever reason, I think it's pretty obvious it needs to be considered) the db loss, etc. out to the antenna via coax. I currently do not have a station up and running but this video has definitely educated me further and I will consider these facts in the future when I do my tower and antenna work.
Thanks William. Happy that I could help. I am not an engineer. Just a lot of years spent building, testing and experimenting with my ham radio equipment. 73, Jim Heath W6LG
Shorted coax should have a high SWR, but if it is lossy the SWR can appear to be low. With the right mathematical formulas at a given frequency you can actually calculate the efficiency of a shorted coax cable! Excellent presentation.
Greetings Jim. I watched many of your videos as I was preparing to test. I passed both Technician & General tests this weekend. They talked me into trying the extra since I was there and didn’t pass. The first extra questions I saw was taking the test. Need to study. Haha. Looking forward to putting up some VHF & HF antennas are the house. 73!
Terrific Brent! Congratulationson passing both tests. Yes, do get on HF and work some DX. I don't recommend DX nets. Learn about propagation either by reading and watching the clusters, or ask a ham who has been on the air a long time. 73, Jim
Jim W6LG Thanks very much. I plan on getting on HF for sure. I have a buddy who is going to loan me a HF rig. First things to do is expand my entry panel in the office ... soon to be called the ham shack. I plan on learning before I leap. Probably get on VHF/UHF first and ease into HF just because it will be easier to mount an antenna for that. By the way, I need to come up with common tools like SWR or Antenna testers and power meters and such. Do you have a video covering this?
Hi Jim, I'm a newbie beginning the process of apprehending basic principals. Kudos to you for an excellent clear instructional presentation; if I learned nothing else I learned when I eventually set up a station, to avoid RG8 coax for a feed-line. I deal with the math part later. best regards Robtn
Jim... thanks for a very apropos video. This re-confirms that I made the right decision to bite the bullet and install heliax between my VHF rig and A26B2 beam antenna on the tower since the coax run is substantial due to site constraints at my QTH. 73!
Jim, I always wondered why any impedence mismatch would be more prevalent with larger coax. It sounds like the coax loss is the culprit. In essence smaller coax masks underlying impedence mismatches (elevated SWR) due to high loss characteristics of the coax. Great video as I learned something useful and can apply this to my own station. 73 James, N0ALE
Very good video Jim, I've watched a few of your videos. I started with valve gear and had an output indicator meter at the aerial and tuned for maximum output and later used an swr meter. Then I went homebrew with a MOSFET p.a. and for years used no swr meter, just tuned at the aerial for maximum signal out. My amateur pal was horrified because I had no idea what the swr was. Probably ten years later I made a resistive bridge swr meter and it proved what I had done was right. I'm now going to use RD06HHF1's which while experimenting with the p.a. have seen ridiculous swr readings and survived. But yes, an swr meter takes the worry out of matching the aerial to the tx. I like the resistive bridge type because the radio never sees above 2:1, the meter shows all swr readings, but it is limited to QRP because of the resistor ratings. An interesting point here, I tried 6m with an FT817 a few days ago with a dipole I was given, I got the swr right down. I called six amateurs and even though their signals were booming in here they did not come back to me. There's something wrong. I took it down and noted not much r.f. present at the dipole, I saw corrosion so I cleaned the aluminium and re-connected the coax. Now much more r.f. showed on my r.f. indicator. I've yet to have a QSO but feel confident it is radiating far more efficiently now. So it is still a good idea to check at the aerial that it is actually radiating. 73, Bill, G4GHB.
Yes, that is a very good idea. I recently took a dipole down that I had made from aluminum tubing from another yagi at my old location. The dipole never performed as it should. I had hardline to the antenna with a short length of RG8X. With Bird wattmeters I determined that there was RF to the antenna. After several attempts at a repair, I have up and took it down. It is now on the ground. Since it was an old driven element off of a 4 element yagi, I did not disassemble and reassemble. My guess, and it is only a guess, is that there is some resistance between the telescoped tubes. The replacement is still on the ground. I made it from pieces of tubing and used a anti-oxidant between the tubes. Also, I put sheet metal screws through the tubes. I will let everyone know if that worked in a video later. Thanks and 73, Jim W6LG
@@ham-radio Hi Jim, I just re-read your comment and it made me think about a 6m dipole I was given. I could hear Portuguese, French and Spanish stations over say a week, strong but I couldn't raise them. On investigating I found corrosion at the SO239 socket, the elements and gamma match. Was that my problem? The band isn't open now so I can't be sure but it won't have hurt it to clean things. 73, Bill, G4GHB.
It was calculating coax loss with high VSWR that prompted me to go to open wire feed. Sometimes though the loss can slightly work in your favour, most rigs with built in auto ATUs can't cope with severe mismatchs. If you have 100ft of RG58 miraculously the radio will appear to be happy. It is not good engineering and is grossly inefficient but sometimes it gets the job done.
Jim, I've been inactive for several decades, life just got in the way!. I just passed my general license (again) and am looking forward to getting back on the air. You are doing a wonderful service to the radio community and I really like your style. Keep up the good work. A lot of my equipment is old (as you can imagine) but I'm looking forward to putting my Kenwood TS-430S back on the air. It's been sitting dormant for a LONG time, is there anything I should watch out for the first time I fire it up? And my Dentron Clipperton-L amp? 73s my new friend Ken
Jim your videos individually - and combined as a reference - are truly amazing. Thank you so much! Couple questions... or statements to confirm my understanding: 1 - is the SWR meter simply measuring watts traveling one way vs what it receives back reflected? 2 - if I understand this correctly the SWR meter is only measuring what was reflected back to it, so it doesn’t know what was actually lost in the coax line. so if we factor what was lost in the coax line (by charts) we can get a better “hand measure” of what the real SWR measure is. is that correct?
1 Both directions, hence the two diodes with one forward and one reversed. 2. Yes. If you know the loss in the coax you can get a pretty good ides of the SWR. I have found that for new coax, the loss charts are accurate. If the coax gets water in it, the SWR goes down and the loss goes up. Thanks again for watching. 73, Jim W6LG
I know this is late, but for anyone else that reads this, yes it's correct. 4.94:1 to be precise. I cheated and used an online calculator. You have to remember to put in 50W of forward power.
Jim , It might be worth emphasizing that we are talking about Voltage here, As in Voltage SWR. And that voltage varies along the length of the feedline. Of course the SWR at the transmitter is what the manufacturers are concerned with, even if as you noted the antennas actual SWR maybe much higher.. How does the SWR affect the feedline losses ?
Such a great video. Very clear explanation. One question. Can we assume the re-radiated power is useful? It has a delay thus can even bring down the signal through distructive interference. Am I correct?
Hey Jim, I just bought a Leixen UV-998 VHF/UHF 25W FM Transceiver and I need to know what type of base antenna I need and what is a good and cheap SWR Meter to buy? I haven't taken the Technician's exam yet but plan to very soon. I'm just starting to be a Ham and I really like to learn more about these radios. Thanks.
Jim, this was really instructive. I am just about to get my license and am finally making sense of all this. Your videos are really well done and helpful. I realize it would not be practical, but if my SWR meter is mounted at the end of the feedline just before the antenna, wouldn't it provide a much more realistic reading of what is going on?
Im running rg8u to a pretuned antenna a tram. THe swr is 1.4 with 5 watts and a 2 at 80 wtts. How can i get the swr better and should the swr be done at 5 watts only?
I have always used RG-213 Coax cable. I like to tune my antennas with the SWR meter at the antenna on a 3ft jumper. Once this is done and the antenna is raised to at least 30ft to its base & grounded to an 8ft. Copper ground rod the SWR should read low at the radio. My equipment runs cool and receive & transmit operate evenly across the band. I do notice atmospheric changes can & will effect meter readings on output from time to time but not the SWR readings. I believe excess moisture on the antenna causes this but doesn't appear to affect the stations output performance. 🇺🇸
Thanks Miguel for the great advice. I agree that moisture will cause changes but nothing that we can easily measure. Happy New Year from Rocklin CA, 73, Jim
Hey Jim, great video. Quick question. I have an swr Meter but it didn’t come with a short jumper. So I just used an extra 9 foot coax cable. Is this ok or will it severely alter things as I tune my antenna?
What losses. Like you commented in a few videos Jim. Attention should be paid to firstly the antenna and applicable losses from it from the Transceiver. Good stuff
Another incredibly instructive video from a totally new guy only a couple months into amateur radio. I do have a question though. Does a stated antenna gain from the refocusing of the power to the airways relative to an isotropic radiator effectively yield more power to the target of the antenna focus direction than is found at the entry point to the antenna (if that makes sense)?
No. An antenna achieves gain by radiating less in some directions and sending that power in another direction. In other words, if you had a perfect isotropic radiator that radiates equally in every direction, and you changed it to take exactly one half of the back hemisphere and send it forward, you’d have a 3dbi gain antenna. You’d send twice the power in all directions of the forward hemisphere. Even when you focus the power this way, it still always expands when it leaves the antenna. Because of this, the power you can actually receive at some distance will only be a fraction of what is transmitted, and falls off by a factor of 4 every time you double the distance, no matter how much gain you transmit it with.
How does this translate for QRP? I was horrified at the lossy numbers in this video - those would be devastating when operating at 5 watts. I'll have to do some research, but I'm very interested to know what this means for HF and SSB & CW work. If I'm using a tuner to get me from 2.5:1 to 1:1 on 5 watts - how much did the tuner just subtract from my overall system assuming I'm running 20 feet or less of Coax? Those are the kind of real world (for me anyway) problems that I'm looking to solve. Thanks to this video, I at least know where to look for signal strength loss and to view the SWR reading with a wary eye.
Intriguing video Jim; gets the gears turning. Do you know of an online calculator that will compute these measurements in the way you did with your video? I can't imagine there is a commercial device that will factor in variables like feed line and antenna losses... let us know if one exists. Thanks!
I have noticed that a lot of hams use the RG8X for short jumpers in the station because it's much easier to route and handle than lets say LMR 400. If you have a jumper or two of the RG8x, will it cause any significan't loss if the bulk of your feed line is the heavier stuff?
Feedline attenuation is measured in x number of dB per foot. Every little bit adds up. Generally short bits don’t matter much, but it all depends on what you’re doing. At 10GHz adding a couple feet of even good feedline can consume half your power! At 3MHz the loss wouldn’t even be measurable.
Thanks Jim this session helped a great deal to better understand SWR. Do you have notes with the math that I could refer to better understand the math? Bob, KK6BXJ
Hi Jim, I think had was interesting, just like all you videos. What in interesting is what you have on the top shelf. Drake twins was my first. I know when things are in close in a cage, DON'T use anything but one hand. 850 volts RF can you say. Getting lost in my thinking. Have a good day 73
I recorded a video about that and have not put it up on RU-vid. I will re-visit that video where I discuss what happened to me. In short, I woke up, came to, about 15 feet away. Thanks for reminding me about the danger of two handed stupidity. 73, Jim
Thank you for this explanation. I am brand new, very low budget and looking to put money where it should go and not end up buying the right gear after finding out the cheap components wont work as advertised. Thinking that if someone can afford the transceiver and antenna that the coax should not really be a financial issue. My question is which of the coax cables available(sizes) would be the best overall choice (dollars aside) for a given frequency range? I'm starting with a quad band mobile rig but will eventually get a base station and thats where the "real"money will go so planning for the future. Thank you for sharing
hi Jim, bought a boat with an SSB sitting winking at me ! icom IC-M710 got any basic pointers so I can listen to different nets. Ipswich uk great videos
Hi Jim, When u are talking to an other ham and telling the power you're using, do you say the actual one or the one you set on your transceiver? As in some cases there could be a significant difference.
Most people use the power at the transceiver out of convenience, but the power at the antenna is more correct. When you get into microwaves where it is very hard to overcome losses and get power to the antenna, most folks use the value at the antenna, since they’ve probably measured it.
Hi Jim. I have a question about SWR. My mobile radio is the President Lincoln ll+, with 10meter, CB(11meter) and 12 meters. I have paired the radio with the Stryker SR-A10 magnet mount antenna. This antenna is a base coil, with a 60" stainless steel whip with just about 1/2" of adjustment on the length. I cut about 1/4" off the whip in order to get a perfect SWR on the CB band. However, the SWR is dangerously high on both, 10meters and 12meters. Any idea of how to get usable SWR on all three of these bands? The only solution I have thought of, is purchasing two more steel whips and cutting them to length for proper SWR and just switching them out. That's not a very solution. Any ideas?
I know nothing about CB equipment. SWR may not mean much. Getting an antenna reasonant where R=50 and J=0 on 3 bands is probably impossible. But again, I don't know anything about the equipment you have. Sorry I can't be more helpful. 73, Jim
@@ham-radio Well; with all due respect, I have discovered that amateur radio operators consider CB as some second-rate communications to be shunned and/or ignored. Quite frankly, the cold shoulder I have received from amateur radio operators, simply because I have chosen to include the 11 meter band on my radio, is making me have second thoughts about getting my license. For now; I will ignore the amateur bands and focus on CB, SSB for now. I have 6 years experience with Marine Corps communications with ATC/ground control while operating land-based expeditionary airfield equipment. I have also served 23 years as a 9-1-1 telecommunicator. I am a total professional, when radio communications are concerned and the stigma attached to the CB band has totally turned me off to becoming an amateur radio operator. I may reconsider amateur radio in the future.
so would measuring SWR at the antenna result in the 5:1 reading you mentioned in your example? If an antenna analyser gives a 1.1:1 SWR reading with 100 feet of coax, I guess its would be different with a 3 foot jumper at the antenna?
Jim, if i move the swr out to the base of the antenna, temporarily (just to get a reading) would the swr read 5:1 ? or would i still have to do all the computations??
One must ask why high power broadcast and military HF installations all use 600 ohm open wire (pipe) feed. Ladder line has some huge advantages over coax.
@chris beerad a balun with the right ratio will get it close. an antenna tuner will get it the rest of the way. some antenna tuners have internal baluns (4 to 1 usually) so you can hook you balanced line directly to it.
Sure. But at 10 meters you will lose about 20 watts out of 100 watts. In other words, it is about 80% efficient. That number assumes that the coax is properly manufactured and that the connectors are good. LMR400 has about half that loss being 90% efficient. RG213 is in between those two at about 85% efficient. I would use RG8X if that was more convenient due to its weight or size or cost or location. 73, Jim W6LG near Sacramento in norther CA.
that was interesting to me an swr at 1:2 allways ment half power 1 to 1,5 is a quarter. so 100 watt out is 50 watt out at 1 to 2 or at 1 to 1,5 its 75 watt out. and im using rg 58 to an hb9cv on 434,975 to the local dmr repeater 5kms away. i got a good signal. 4 out of 5 pinns on an hytera785 pinn_o_meter. well i can reach the repeater on a handitalkie outside my forestcabin 250milliwatt out. so as low power as possible on the hytera.
Hi Jim. I'm kind of puzzled with my feed line on my 2m antenna. I have a Comet GP-1 antenna with 60' of LMR-400 between that and my radio. I am using a RigExpert tester and it repeatedly is showing me computed SWR of > 2.0 but < 2..2. I have redone my PL-259 connectors twice. Measured SWR right at the antenna with a 1' piece of LMR and those reading came in close to 1:1. I'm puzzled. I'm at the point of replacing the LMR-400 with something else or possibly not using the solder-type PL-259 connectors and going with either pre-made cable or crimp-on connectors.
Do you have ferrite beads on the coax at the feedpoint? I am wondering if the reading is from common mode currents. Ferrite beads at the feed point and at the entry to the house may tell a very different story. Your SWR meter may be rectifying current on the outside of the shield. I don't think it is a problem with the coax, That's my first guess after a fast read. 73, Jim
Hi Jim. I thought something similar and I coiled the ends since I didn't have ferrite beads large enough to go around LMR400. I'm now suspecting I might have cold of loose solder joints not eh PL-259 braids. Was thinking of cutting off the PL's and buying a crimper and trying crimp-style instead of solder-type. I'm not suspecting the cable either..but it is actually DRF400 instead of actual LMR400. I was told the loss per 100' is the same..maybe the quality of construction isn't??? ..Dunno. Kind of at a loss (pun intended).
WXField, I have used Davis RF's DRF-400 for several VHF/UHF antenna installations, including ARES stations at local hospitals, and I have never had a problem that I could trace to the cable itself. The connectors I attached were occasionally a problem though, especially the solder-on types. It can be tricky to get the coax braid soldered to the connector correctly without melting the dielectric and ruining the cable's electrical characteristics. I have certainly over-cooked my share! You didn't mention which Rig Expert Analyzer model you are using, but I know some of them include a function called "TDR" (Time-Domain Reflectometry) which can identify opens, shorts, and other damage inside a run of coax cable that isn't visible from the outside by looking for reflected signals and computing the distance to the damage based on the signal's round-trip time similar to the PING test in computer networks. If you suspect the cable, you can test it with a TDR, but I would look pretty hard at the connectors and then try a common-mode choke of some sort, like the ferrite beads mentioned earlier. If I recall correctly, ferrite Mix #43 is recommended @ VHF/UHF frequencies, or you can try any other common-mode choke designed for VHF/UHF at your intended transmit power. 73, and best of luck!
Figure it out!! I mounted the Comet GP-1 to the top of an old satellite TV mount (coincidentally called a j-pole mount). There's about 5" or real estate to mount antennas to on the business end of this mount so below the GP-1 I had an omni-directional digital TV antenna as well. I disconnected the GP-1 and moved it to an area about 8' away from the TV antenna and my SWR maxed out at 1.2 across the 2m band. So there's something wacky going on with the TV antenna that's interfering with the GP-1. I will find another location clear of the tv antenna to mount the GP-1 and that should be it.
Hi Jim just got a marine radio uk its my first. its for my boat i bought this year can you tell me which swr meter i need to tune it in as i cant find any that go up to the frequency 156. to 174mhz i see only ones that go upto 125 0r 130mhz looked on ebay ! thanks for your good advice so for
Hi Jim, I have an old SWR meter I am trying to make work but cannot figure it out. It is a Monarch FS1 - 5 It is from the late 60's according to the sticker on the top. It does not have a switch just 2 meters - 1 for power and 1 for SWR. Any input would be great Thanks in advance KB1WOR
I like to know can i use my AV-400 meter that is 140 to 525mhz for 50 to 54MHZ i know the meter is out of band but i just like to know how fare out it would be and if it can tell me if my SWR is even close to good
So Jim, regarding your own ham station, I'm noticing your top grade antenna rotators, assuming you have towers, which means they are probably not close to your radio shack, so I am guessing you run a minimum of 100 feet of gas-filled microwave cell tower hardline to your tower yagis, and compensate for any signal losses with RF amplifiers pumping close to two "'gallons", so you've probably "Worked All Galaxies" ??
The rotators are not Yaesu's best model or most expensive. The feedlines are hardline that I purchased surplus. I made my own coax connectors from copper water pipe and UHF connectors that I had in stock. Two of my amplifiers are homemade with parts purchased at swap meets and shows over 50 years. Some of the parts were gifts from Wolf in Germany and Stan in Russia. Both guys were very generous. The Drake equipment is decades old and purchased over decades. The K3's were purchased new and I paid full price. The same is true of all of the Elecraft equipment. There have been some other gift from WB6ROW, W6BQW, W6FR, W6ZAF and others now SK. The land was purchased in 1978 for a little over 20K and I built the house very economically. My feedline losses are in fact, very low. I think that covers everything you commented about. Jim W6LG
Thanks Jim for all the information on your radio room. You are truly a "Ham's Ham" in the same tradition of the first radio operators who designed and built all their own gear. You have managed to collect and build a very impressive station which truly reflects your ingenuity, knowledge and skill in electronics and radio. You have merged your scientific background with history into the hobby, and your videos are truly an "Elmer" to so many hams who don't have the opportunity to learn from experienced pros like you. Keep up the 'fine business' and thank you for reminding all of us to get up out of our chairs and walk to stay healthy ! '73
Thanks and I am trying. A few of the new diagnosis are very discouraging. I go for more tests next month. Some are for the third time. Fortunately, I have the ham radio hobby and can do the RU-vid videos to keep me active. Part of the time I am on oxygen which helps a lot. I did not smoke and seldom drank alcohol. Just bad DNA I guess. We are still researching that. Thanks for the wishes and support. 73, Jim
On the surface, that sounds like an easy question to answer. My answer is yes. But, others may disagree for lots of reasons. SWR is a measurement made with some kid of device that transmits. It is a way to measure the match or mismatch at the feedpoint. You know, this is such a good question, I may do a video about this. 73, Jim
@@ham-radio I've been a follower for quite a while now I think I lost touch and then resubscribed at spme point iam glad i can help give back 💪😁👌 .. i was only asking because iam reserching my foundational amature radio licence and i have been playing with the Rtl.SDR and 27mhz so I was wondering whether I bother with swr for the RTL SDR i have a common mode choke in my home made dipole and that seems work wonders ...also can the device (radio) change the swr of the antenna .. 73's from Bundaberg Queensland Australia ..
Built 10 meter vertical out of ham stick that survived accident. SWR at 28.4 is 1.09:1. Most new hams feel great I don.t. My gut says this antenna is not doing what it says and might be best not used. .AA54 reads R =49.5 Z=50 Xl=-4.4 Xc=1265mf. base on pvc 4 feet up radials 45 degree slopped.to 1 foot off ground hard clay sand mix. My coax DB loss should be under 3db as lmr400. 30 feet. You definitely got my attention on this and antenna is currently down. This antenna must be higher swr as shown in video, Tossing this out as new ham and doing it alone so no elmers or help. Like videos as are not long and too deep. You got my attention as assumed low swr meant all is well.
One of the best antennas I have ever had was built by a Navy communications master chief. He made his own ladder line with 1/2 inch pvc pipe and if I recall, 12 gage solid copper wire. That antenna still rocks to this day, and minus the tuner I get excellent SWR's with his balun and the short run of RG213 into the shack.
Hi Matthew and thanks for the message. Well, when you can put up a larger antennas and better coax you might see a difference in performance. With your current antenna system, you are putting about 3 watts in the coax. About 2/3 of your transceiver's power is being lost in the coax. I have worked some guys in VU over the years. From W6 to VU is a difficult path. 73, Jim W6LG
Fact check. My 1984 ARRL handbook does give a graph for calculating the total loss for mismatched line. This appears at the end of the chapter on transmission lines. So older handbooks have the information needed.
Thank you for explaining this subject. Is the heat loss from the reflected energy absorbed by the tank circuit in the tuner and the ground plane only? With much of the losses due to the coax itself, how much better would a balanced feed line be between the antenna and tuner if any? Also, please explain the benefits if any of "shielded parallel lines" aka "shielded balanced transmission lines". Can any power escape from the coax as radiated rf ? It sounds like you are perfectly explaining some of M. Walter Maxwell, W2DU book, Reflections: Transmission Lines and Antennas. I do not understand much of Maxwells theories, It's way over my head. I have lots to learn. I also found a good source of information on this subject in Stephen C. Ward, WC7I article at hamuniverse.com/wc7iswr.html Thank you for making this video, I am going to have to check out your other videos on the SWR subject. Thank you again.
Ok. Time to get a ham radio license and become part of the Amateur Radio Service. Drop the CB lingo and bad habits. Join us! You will find it is a lot more fun. You may be able to talk around the world from your truck with 100 watts and a decent antenna properly installed. I probably should do a video about installing mobile HF antennas. I did manufacture them for a few years. Take a look at the ARRL website about how to get a ham radio license. We need guys like you who are mobile much of the time to join us. 73, Jim
Thanks Jim for all your videos. I enjoy fun and laid back atmoshere on those "specialty" channels but truly appreciate your knowledge. At the end of the day it's about getting a clean signal ON freq..... whichever one may choose. But I do think I'll press forward to get a ticket none the less. Thank you sir
Jim, I’m just getting back to Ham radio after many years. I purchased an ICOM 7300 and I will be installing an End-fed 1/2 wavelength 133ft wire antenna to cover the range of 80-10m. The antenna is supposed to be resonant at 80m. What quality coax feed line options do you recommend that I purchase; cost is not necessarily a consideration at this point. I believe that I will need approximately no more than 30 feet of feed line. Your recommendation is appreciated. Joe M. KA5LJB.
ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-xfqlun3bdI0.html Watch that video regarding the antenna. Despite my suspicions, I did not find a deception in the description of the antenna. Also, read the review by the ARRL. In any case, I recommend RG213 or larger. Apparently, the design is similar to a Zepp or J-Pole. Good luck getting back on the air. 73, Jim
Pretty good video, but not so much about SWR, but about feedline loss. When talking about SWR better to do with lossless calculations so can concentrate on SWR. Of course feedline loss affects SWR readings.
In order to answer your question, we would need to know the length of cable you need, and the highest frequency you will use over the cable. Coax Cable loss is normally expressed as a value (in dB) at a given frequency for a given length of the cable . For example, LMR-400 cable has a loss of 1.5dB per 100ft of cable at 146MHz. Coax cable loss tends to increase with frequency, so the same cable has a loss of 2.5dB/100ft at 435Mhz.
It seems like you are equating SWR as being transmission line loss plus power reflected from an antenna impedance mismatch. I don't think that is correct. While both result in reduced effective radiated power, they are different problems.
SWR is one component. Line loss is another component. Higher SWR result in greater loss. Line loss makes the SWR look lower. The highest ERP is the goal. If you do see an error in the video and want to let me know when that occurs, I sure will do a correction. Thanks, Jim
