Peter. don't worry about teaching basic stuff. I have been around, like you, many years. I think around 43 years. Refreshers are never a bad thing. Thanks for all you do. 73. WA7SDC
Hi Peter, I was watching this subject on a US channel and Gordon H Bennet they love to waffle, some of them,.. showing manufacturing charts, ferrite values, mixes etc… glazed over my eyes… thought, what does Peter say… and Shazam, easy to follow, practical and importantly…understandable. I was licensed in the mid 90s and there was no RU-vid and internet was in its infancy… now because of life I couldn’t continue radio and stored my stuff, again now because of life experiences and circumstances I can,,, I’d become a cabbage stuck in the house but thankfully I have a radio ham friend who got my rf flowing again. I’m learning a lot from you and a couple of others who have the Occam’s razor approach,,, I have a lot of re education to do. S O thank you for taking the time and interest in posting these videos, you have a pleasant personable approach. Best wishes to everyone 73 Subscribed.
I love your videos,… watching from Kentucky “The Bluegrass State “ . The USA 🇺🇸 Great information . This will be great for my 10 Meter Radio . Thank you 🙏🏽.
It does not matter how long you have had a license, you can always learn more or, I did give up the hobby for years and forgot a great deal, its good you have taken the trouble in putting these film out. thank you.
Thanks so much for catering to us new HAMs! Passed my general a few weeks ago and I'm struggling mightily with noise at the receiver now that I'm trying to work HF. So much more tinkering and frustration moving from UHF/VHF. Really appreciate the concise, easy to understand video!
Nice informative video Peter, isolators or chokes like these really do work well in many instances and a nice small project for new comers too, so often forgotten or overlooked.
Hi there Peter, love your informative and enjoyable videos, RF noise is certainly getting worse in crowded urban areas.This video really addresses this problem, thank you for sharing this, keep up the good work, cheers and 73’s, Sam from South Australia 🇦🇺
Thanks Peter,. As a G3 now living in an urban environment and about to set up a HF station after a lengthy hiatus from the hobby your video is a timely reminder to consider including an antenna line isolator.
Thank you for the video. Good information. I listen carefully to the senior hams and electronic techs and do what they suggest. So far no rf burns after 30 plus years. Thanks again for your video. N0QFT
Well explained Peter another good video. I use a line isolator just outside the shack window on the way to my end fed half wave antenna. It is at the radio end of the feed and it really helps with my noise floor and of course, i do not suffer any RF in the shack. A worthwhile, practical item to have installed.
I used your advice and use a line isolator due to rf burns (quite bad) only on 20m .its done the trick!!! Thanks for all your great videos and look forward to the next one 👍73's
Thanks Peters. By the way I bought your last OJV-80k a few days ago which you recommended in the last video, tuned it yesterday and it works an absolute treat! Best £20 I've spent on ham gear yet!
WRCX212: Thanks for the info. By using an MFJ line isolator along with a RM ITALY low pass filter, my swr is flat across the whole 11 meter band, and half of 10 meters. Now I'll keep my fingers crossed if works good with an amplifier. Great video!
Thank you Uncle Waters. MI7RXD I'm loving your videos. Today I'll set up an EFHW 49:1 66 feet out my apartment window. Top flat bedroom. I'm excited as I've only been on 20m so far. Good man for the valuable information
Hi Ronan. That antenna will let you enjoy 15m and 10m DX when thise bands open up. Check them regularly. You will be amazed what you can work. 73 Peter
@@watersstanton Uncle waters. I setup my EFHW with 66 feet. My yaesu 450 tunes 40, 20, 15 and some of 10m. The bottom 500 of 10m tunes but not above. What can I do to cover all of 10m? The top end of 80m tunes too. The antenna is only set up a few hours.
Yep, a RF burn makes you pay attention, just as a shock from the main does. But it makes you avoid it the next time. It doesn't need a lot of RF to give you are burn either! Good video. Keep then coming.
Hello Peter, I'm not New amateur, I'm an old fool, and yes I know all this stuff, it is nice to hear you teach the New amateurs, plus I enjoy it myself, I do forget things you know,, it doesn't hurt to get a refresher , and for New amateurs line isolators are a good thing to have in line always.
Thanks for a very good presentation. Regarding the swr meter problem I have an alternate theory. Once you get RF currents on the outer part of the coax shield, the outer shield will be a part of the antenna. So when you add a line isolator or change the length of the coax, the antenna swr will actually change, but not due to a faulty meter. Looking forward to see more videos from you in the future. 73 de Sm5lym
Apart of the very important information about line isolator thank you also for your beautiful English which is absolutely understandable and clear. 73 de EA4CWW
Yes, RF burns are awful! I was licensed in 1962 as a 12 old boy that had no (or little) electrical sense. And, playing with the great old tube rigs RF burns happened until I realized what was going on. My rigs now have line isolators and consider them a must. Thanks for all the great videos!! Tom, W0GEO/4
Thanks for the isolator video as I use one on my 80-40 meter shorten dipole. Don't have a problem with RF burns or excessive noise with about 125 feet of coax cable to the antenna. Lyle VE5EE
RF burns were a problem back in the 70’s for me… I had (I’ve restored / use that mic today) a metal microphone and occasionally I would touch the radio or amp and get zapped! you learned quickly not to do that but it was obvious that I had a common mode current issue.
This is so helpful and I love how you also help me as a 11 meter operator any information on the cb band is most welcome thank you sir from 416 Trinidad 73s.
Just shows you amateur radio is a learning hobby… I am dedicated to qrp operating very low power usually portable but do tend to suffer a lot of receiver noise so I’ll certainly try that 1s point could be the difference of making that contact many thanks 73’s Phil M6dnu
I like end fed antennas what I have found is a good ground system works best , my station is grounded and my antenna has a short ground off the match box , I do have a line isolator right outside my shack
I watched the video, then read the comments and realized I must have lost focus and had to go back and watch again. Interesting stuff. So a line isolator is just a choke as I now understand it. Yet some call them baluns or ugly baluns, so I expect a true balun is different somehow. It is constant learning, this.
@@watersstanton I put my two toroid wrap at the radio end and 3 clamp on at the antenna end. No noticeable reduction in the 80m noise I'm targeting. Pernicious noise this. Working on a loop to try to locate the source now. Kind of tough for an 80m handheld loop into a handheld haha.
I have a coax choke mode out of a small soda bottle about a meter from the feed point of my EFHW. abt 10 turns of rg8x. Makes the EFHW more useable with a LOT less noise. S0 to S1 noise on most of the bands 80-10.
watersstanton, I have used RG58 without issue, with moderate SWR a short length does not have significant loss at HF. RG142 is less prone to the centre conductor moving when using a sharp turning radius. The jacket is also teflon which has some advantage. Not a big deal I know but with the price of the FT240-43 cores it is worth doing a good job. To reinforce the point of the video though these common mode chokes/line isolators can have a huge effect.
Thank you for these video`s Peter, i enjoy watchig and learninhg from them. I was wonderig if there was any benefit in having two line insulators, In my case on the Carolina Windom i have one after a ten foot drop of the coax, coul i put another one by the rig. Regards Brian G0GAQ
My 20m end fed with 9 to1 Unun fed with coax problem was the RF staying in the house, as proven by when I would transmit 100 watts the electric kettle with touch electronic controls (a bad idea) would turn itself on, so every time I spoke I was using 3.1 KW, as long as water was in the kettle I could have a brew!
Hello Peter . Thank you for sharing your interesting findings . On your video you mentioned sheathing , I presumed that you was referring to the screen ?, there could indeed be potentially an electrolytic charge between the inner side of polyurethane protective sheathing & the copper protective screen & the central dielectric core . I really ought to add Peter that the above it is quite complex science as it involves electrolysis law , ie , AI,3 ++3,e , I shan't go into any great detail , but the most efficient way of protecting RF burns is grounding of the radio & antenna , or any electrically charged device come to that . Again I shan't go into all the in's & out's of the radio transmission science as it's quite involved , by and large radio grounding is essential , for some unknown reason the UK lacks the grounding method & I've never understood why ? , grounding has so many benefits from protecting the front of the receiver against high electrostatics in the atmosphere , it prevents electrolysis / electroplating of the coaxial cable & prevents electrolysis pitting on antenna . Further more I ought to mention that America takes radio grounding very seriously & they realise all the benefits on grounding , further information on grounding radio transmitters & receivers can be found online. There is a certain amount of grounding on most 13.8v transceivers if used on a 240V mains power supply , though this is only a primary grounding , ideally the antenna should be grounded , particularly if the transceiver is powered with a 13.8v battery / mobile or portable use for example.. Grounding also helps improve reception signal by creating a much greater potential difference, hence the receiver is between ground & atmospheric electro static path , grounding is generally more effective on receive then transmit due to the dielectric effect. I have created a complete grounding system on my transceiver set up & it works very well with significant results. There's certainly no harm in using a line isolator , as in every little helps . With all due respect I should add that the RF line transmission path of a conductor is unknown as RF on any physical metallic radius cannot be measured by using PYE or PI for example , the transmitted electrons will travel throughout the whole path of the entire inner conductor & not just surface , however there can be a generated electrolytic charge effect between the inner central dielectric core & the screen & can create an electrolytic charge between the inner polyurethane sleeve of the coaxial conductor this process is eliminated by " grounding of the radio & antenna ". I hope that the above has been of some help . Julian Robertson Electronics engineer.
Always enjoy your videos. Could you use an isolator both ends of the cable, so one after the tranmitter and one before the aerial and would this be better?
I have been using 240-31 torroids for noise and choke work and 240-43 or 140-43 for my 49:1 transformers for EFHW antennas. My noise floor is very high and more so after dark when neighbors lights are on. Over time I have used torroid cords or ferrite beads on most of the offending electrical equipment in my house (there is a lot) and the coax from all my antennas. RFI noise seems to always be a work in progress. K5FIT
A dipole antenna is a balanced system and a coax cable is an unbalanced transmission line. You therefore need a balun between the coax and the antenna at the feed point. The reason you have RF on the coax feed-line is because it is acting as part of the antenna. Your antenna will perform more as expected with a balun. If you're still getting excessive RF on the feed-line then, yes, add an RF choke!
Ian, I explained in the video why I had not shown a balun in the drawing. A balun does NOT stop RF flowing down the coax, and many offer little or no feeder isolation. A line isolator is an essential HF item, balun or no balun.
Is there a 1:1 unun? You can get rid of lots of common mode current by finding the ideal length or by avoiding bad lengths of feedline. Not sure if that also helps with noise but could do as everything will be more in tune and more in balance. I would say that once you find an ideal combination of feed line length and antenna tuning you are more likely to bring in the wanted noises. Probably a higher gain and more usability across that band.
When you say put the line isolator at the transceiver end does that mean the transceiver end of the coax before it comes into the house or use a short piece of coax to connect it right at the actual transceiver?
Thanks very much for this and your other videos. Question: you mention that it is valid to place an isolator at either the feedpoint or at the rig. Is there any benefit from using one at both ends? I have some very long feedlines to some of my antennas (50 to 75 meters). 73 de WN6NW
Both is pretty good particularly if the feed line picks up signal directly from the antenna. A choke at the antenna can be defeated by the feed line acting as its own antenna so if you have only one, near the radio is probably better. If you have a really long feed line, clamping ferrites onto the feedline at intervals less than a wavelength will help prevent parasitic radiation where the feedline acts like antenna segments (reflectors or directors). I also put ferrites on the DC power lines and even the microphone coil-cord.
im going from a wire antenna to a ground mount vertical hustler 5BTV and I burry my coax , would you need a line isolator for a vertical that is well grounded ?
Changing from switch-mode to linear power supply will see a massive improvement in noise reduction. I use a 70 amp hour lithium polymer battery for my radio, so its completely isolated from mains power and the associated noise. My desktop led light generates some noise when i touch it then release, its noticeable. For this reason everything is switched off while playing radio.
Many ham radio quality modern switchers have quiet switching circuitry and very good filtration implemented on both AC side and DC side. You will not notice any RFI on ham bands if you get one.
I have detected the same thing a long time ago using a cheap ? SDR Funcube as a receiver: the noise of the computer's switched power supply practically blocks the capture of weak signals, but a miracle occurred when the computer worked only with batteries. Perhaps some type of high pass filter could be "studyed" to block this electrical noise since it is usually noise caused by harmonics of frequencies not very high, 70 khz or similar, emitted with electrical crackling in commutations or in switching power supplies.
Once again a great video Peter. A possible subject for you to make a youtube video on, could be whether or not a separate station ground using an earth rod purely for your radio shack is required, or would the house earth be sufficient as in my case where my house earth is a ground rod (TT system). You can read so many conflicting articles on the subject in books and on line. Mike G7PTV.
If the house mains, electrical power, is unbalanced then you will have a current on the ground rod. This current will produce a small voltage and that voltage will be felt by the radio and antenna system. More important is how distant is the ground; if you are 1/2 wavelength from ground then it might as well not exist (for RF, it is still a safety for DC and mains frequency).
Hi Peter. I'm not a ham. I'm a just-retired SWL, who took up SDR in my later years as a hobby. I have several receivers and they do seem to be very, very sensitive. I'm in the suburbs and we seem to be surrounded by RF noise. As well as the ubiquitous VDSL, my own computer monitor creates various types of noise from 150kHz upwards. LED lights do too. I'm also about a mile from overhead power lines and just to cap it off, there is a big MW transmitter for LBC, BBC Radio London and others, about two miles away. Researching the noise problem has led me to the use of ferrites and I'm curious about your use of the term line-isolator for what, in my limited understanding, I call an RF choke. I do understand that for transmission there are many considerations beyond my simple notions of catching waves and getting the tiny currents cleanly into the receiver. I may have missed it, but did you ever do baluns/line transformers? I have been winding my own. As well as the RF chokes, which I sometimes have at both the antenna and the receiver, I will have a 1:9 transformer, for example, at the point where a long Beverage antenna connects to the coax. Thank you for sharing your insight and I for one would be interested in more videos about coping with noise reception.
Hi Alan. The line isolator is an RF choke. You are working along the right lines. Always include one in your coax feed just before it enters the receiver.
Much appreciated, thank you. I'm getting a bit confused over the names of devices. Is a "line isolator" the same as a "common mode choke" and the same as a "1:1 balun"?
@@watersstanton even though 1:1 current balun's primary purpose is to force equal current on both dipole shoulders, doesn't it also double as a common mode choke in the sense that it inhibits current flow back on the coax?
G'day mate. Great video. How would you reduce or eliminate the EMI or "whining" coming from a vehicles alternator (generator)? I have a Barrett 2050 and when I'm in the 27MHz range, the interference is extremely loud and powerful. As the revs in the motor increase, so does the pitch in the "whining". Any help would be appreciated. Thanks.
Hi Peter I’m new to this hobby and I’m studying for my foundation license,I’m just getting my shack together and I’m slowly learning more and more ,can you have a rf isolator at the antenna end and another one at the transceiver end ? Many thanks ade Sheffield
Hello Peter. I'm building a 1:1 current balun to place between the ladder line and coax. Could I also add the coax line isolator by the radio; any down falls?
Even some of us older people need a reminder now and again..... I for one had forgotten why I had one installed. It was just installed and forgotten about it. I use old cathode ray TV tube ferrites as they were cheep (free) at the time. 73 g6wzd
Depends on the antenna! With a dipole you can put it at the feed-point, but if your using an end-fed antenna that relies on the coax shield as the 'counterpoise', you would want to install it 'away from the feed-point'. There is also no reason why you couldn't install more than one isolator/choke for additional effect.
Graham, in order to deal with the issues I described, the isolator must be placed at the radio end and before the coax down lead enters the VSWR meter of any ATU. Putting at the feed point of any antenna will not deal with the issues. 73 Peter.
watersstanton Great video. Thanks for making it. Your reply is a little unclear to me. Is this what you’re saying? Radio > ATU > SWR Meter > Choke >>>>> Antenna? To my thinking, this prevents the RF energy from interfering with the SWR meter and getting into the radio. i.e. The RF energy coming down the feed line, toward the radio, is “choked” out. Also I’m a little confused about commercial antennas that have baluns or ununs and make statements that they are preventing RF energy from reaching the operator. If I understand your video, they don’t eliminate this; an RF isolator such as you described would still be important to have. Or does a Balun also perform this isolation/choke but an unun does not? Sincerely, still confused and trying to learn!
What angle postion would be best to use for short range. I know that 10-40m nivis wont work. I wounder if i could use a 10-40m End fed for some local use within 100 km. I never used a End Fed.
A half wave end red works like a dipole on the lowest band. On all bands you can regard angle of radiation to be similar to a dipole. 5-8m would give short skip.
That’s more like a hot needle. Forgot to reconnect my ground once and got a bad burn from the knobs set screw of my Kenwood 520. Great channel 73 wd4dda
Ah RF burns. well I used to make swimming pool liners that used HF welding bars i've had brass bar with go on my fingers and various parts of my hands, the smell is exactly as describe, ony good thing is that is quaterized right away so it smells worst than it feels, but it still hurts !
Hi Peter, l have found my way here after watching your 20m ‘L’ counterpoise antenna Video and wondered if l will still need this line isolator my coax run will be 49 to 66 feet to the antenna. Also is the Fair-Rite ‘FT240-43’ type (61mm diameter) ferrite any good for this please £9.75 of your majesty’s pounds fitted right after the transceiver and before the swr meter? Sorry for all the questions 🙈
What role does using a lightning arrester / surge protector where the shield side of the cable is connected to ground? Would that not stop current flowing back into the shack by taking it to ground?
I've read where line isolators are supposed to be connected near the balun/unun outside, then read where they should be connected near the transceiver. Which one is correct?
