What should be the length of an EFHW 40, 20, 15 and 10m multi band antenna? 73 de vu2eii

What I see is a Diplexer and a Triplexer. A duplexer is a device that lets you Xmit and Rx on the same band. A duplexer uses cavity filters. Like a house with two apartments in one building is called a duplex.. Two houses sitting side by side is called a diplex.

How did you get 4 radios for free? I finally upgraded to Extra class recently, but with a daughter being born in 2 months, and my wife migrating from Europe I simply cannot afford one and college at the same time. I have tried to find scholarships to be able to buy an HF radio, but so far no luck. Many are for high schoolers, or undergrads. I am 28 in graduate school (rips through any spare income i have), in security studies, radio is a theoretical hobby. I cannot call it an actual hobby until I stop studying and start doing. I have considered getting an RTL SDR 4 soon, but like you said it does not perform well for HF so I am not sure how to get into HF without dropping 1200ish for an icom i7300, another hundred for a power supply, and another 300 or so for a multiband hf antenna because id rather start with an antenna that works, so i can get an understanding for how antenna's are suppose to perform before i start building them. Outside the RTL SDR, it just doesnt seem economically feasible for "young blood" to enter the radio field, simply because it is not easy to get an HF radio. In the meantime, until I figure out a way to get a starter radio, I will keep studying free KZbin videos on the topic so i am making progress, but i mention it because it seems to be the limiting factor preventing young people from doing it. Hams are mostly older because older men have more disposable income. If there were a scholarship, or a radio giveaway for young extra class holders, it would push more young blood into ham radio because then they would see it as practical. From an economic standpoint, if i have an interest in computers, and HF is a 1.5k starting point, but Hack The Box, and TryHackMe have free options, and the cheap options are $15 a month, it would be more feasible to spend 3 years learning computer hacking instead of learning radio, because hacking could be practiced hands on. A rasp pi, with vulnPi software to practice hacking is also what $35 at cheapest? $35 for hands on practicing hacking your own machine & $15 a month to practice hacking virtual machines on HTB and THM versus a 1.5k entry point to Ham radio for HF. Naturally, studying hacking provides a better ROI than ham even if it is not a career path. I am bringing all of this up because maybe the older hams can create scholarships for young hams, hf radio giveaways, or some other way to get equipment for those serious enough to study to pass extra class that would actually learn to contribute to advancing HF if they had the equipment. If I had an Icom 7300, or something starter, I would first learn it in detail, then look for ways to replicate its functions in an add on to my rasp pi 4, and post results to lower entry cost into it, possibly selling pre-assembled kits. I'm sure, others if they had the opportunity, especially younger than me, would work to advance things even further. How awesome would it be if the younger generation found ways to implement HF technology with smartphones? Maybe HF controlled over an AREDN Network using a phone, so texting and calling could be done wirelessly over HF mesh network hybrids? What about younger generations launching a Rasp Pi 5 into a space, on the basis of an AMSAT kit, that is more than just telemetry but is actually controllable from a ground station, especially if it had a Linux OS on it? Dragon OS can be put on a Rasp Pi, what if one of those were launched, and a club could control it, allowing younger members to play with a full blown sigint computer from space? The fact Meshtastic is catching on quicker than HAM radio, due to affordability and integration with smartphones should highlight the cost issue, and the type of interests younger generations have. KM4ACK has some videos on how to turn a cheap rasp pi into a ham radio rig, those help with the cost issue for young people. More low cost options are needed. Since 1980, wages havent kept up with inflation, so if radio cost doesnt decrease, it will only get harder for each new generation to get into from continuously decreasing disposable income. V/R Formerly KE8QVP, now AD8MC

I know what an UNUN is. But what’s an UNUM ?

Our enemies can’t take out our satellites without taking out their own satellites, and ruining space for everyone. Space junk will become a serious problem. Only an enemy with no satellites would be willing to do this, but I don’t believe any of them are capable of doing this.

I get 1.1 on almost every band. I do not use a tuner. I use a ICOM 7300 and my antenna 75-10 2K version. 20 feet at shack and 70 feet at other end.

De très très bon reportage mais malheureusement jamais traduit donc on zap tous you tube merci

Hi Mike I just run a cross your u-tube . No 160 meter end fed . What kind of unun and current choke do you think works best for the 160 meter end fed. I did like your video very much . 73 kr4wx

The unun you showed is a 49:1 for a EFHW, not a 9:1 so important for folk to ensure they buy/make a 9:1 unun for your recommended wire lengths which need to be non resonant

*promo sm* 😀

Unun not Unum pronounced un-un.

lies and myths transmission lines are not circuits and font carry currents as claimed here. The line WILL carry unwanted RF currents if its IMPROPERLY TERMINATED. IOW, your need for this nonsense is due to a MISMATCHED ANTENNA FIX THE ANTENNA and stop playing games with ferrite clamps and baluns

Not so sure about that “never near the unun.” That assumes you will be using the coax shield as a counterpoise AND that the coax will run perpendicular to the end fed wire. If your setup requires the coax to run parallel and under the antenna wire, wouldn’t it be better to put the coax choke at the unun and run a separate counterpoise perpendicular to the end fed?

🙏 𝐩𝓻Ỗ𝓂Ø𝓈Ｍ

The transformer you showed is a 49:1.

ρ尺ｏΜ𝐎ᔕᗰ 😄

UNUN or UMUM a big difference it's UNUN

I’m confused, and new to ham so forgive , but if the coax is acting as part of the antenna, then wouldn’t this be an off-center fed rather than an end-fed?

just found your channel and subscribed. Thanks for posting these online. Love learning from youtube.

Hi from UK :) . I enjoyed the presentation, many thanks ! SDR UNO has inbuilt AM and FM hw filter that you can activate on one of the panels. Also the RF gain can be lowered a bit . If that doesn’t fix it, then we are back to the intermod issue. I have problems with switch mod power supplies (in everything …) causing spikes at about 70kHz spacing. Best Wishes - David G5YAX

You mentioned nothing about Half Wave end fed antennas, during your otherwise fine presentation, which I enjoyed. I will be receiving a KM4ACK half wave antenna soon. What important information should I know re: the DIFFERENCE between a regular end fed antenna and a half wave end fed antenna, for instance, would I still require the feed line choke balun using the KM3ACK unit? Thank you 73 N4ANO

@28:29 the trivial change of winding bi-filar or tri-filar making this into a transmission line as opposed to a transformer was a aha moment for me. Thanks so much!

mix 31 best

Superlike👀! Increase your stats - P R O M O S M !!!

Ground mounted vertical radials are affected by the ground, their radials do not have to be resonant (1/4 wave lenght) because the ground is different in different places.you can use from a few the as many as you can but after 30 or so it does not make a big difference. This guy does not like verticals.

Thanks Sharing 73

I enjoyed the presentation. Thank you for sharing!

UNUM - REALLY?

73, as a german ham i want you to ask - do you know why they (in the Zeppelin) used hydrogen instead of helium? i know! i also would sell no helium to nazi germany this time! thx for this Dokumentation video , you put a mass of work in.! and you done ufb best greez, dg2r?

What I did was recommended by MyAntennas for their products, even though I use a much cheaper (yet still amazing) MFJ EFHW. To stop common mode currents if your transformer is up way high, like in my 50’ flat-top deploy, ground the shield of the coax just before it enters the shack. Also, for EFHW’s they use a 49:1 auto transformer, not a 9:1 unun. 14 turns of wire on one side, 2 turns on the other. The formula is : (14x14)/(2x2) = 196/4 = 49:1. The impedance at resonant frequencies on EFHW’s are closer to 2500 ohms. 9:1 ununs are good for non-resonant “random wire” antennas and bring the feed point impedance close enough to 50 ohms that. The swr is 5:1 or less across the HF band, which almost any tuner can handle. If you use a 9:1 unun on a wire cut perfectly to be resonant as an EFHW, it won’t offer enough of a match to get your SWR down on the bands where it’s resonant. Ironic, huh?. Which is why it’s advised you build “random wire” antennas at odd lengths (31’, 41’) to avoid this. Otherwise thx for the video, I’ve had amazing fun with my EFHW, and work 40m and 20m regularly without a tuner across the entirety of both bands with my swr ranging from 1.09-1.4. No tuner required (aside from the all important auto transformer).

Just correction, it is UNUN , not UNUM . UNbalance to UNbalance matching transformer. Otherwise good explanation, on how EFHW antenna work.

Hi, All, this is Bill, WG0R. I talked with Dave Foster a few weeks ago about my one of my Windom "drooping" elements breaking, and mentioned that I wasn't getting meeting notices since Summer. I have just subscribed to this meeting forum so, hopefully, I'll get back on the distribution. 73!

excellent presentation, as always Mike! and thanks to Anthony to posting these on a channel!, N0VLR