An Easy Trap to Fall Into (when using an “antenna tuner”)
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- Опубліковано 10 лип 2023
- Note: This is a video from www.PATREON.com/N4HNH. It was available to Patreon team members over a month ago. It is now being made available for public viewing. Patreon team members have access to exclusive content. Some content is eventually released for public viewing.
There is an easy trap to fall into when it comes to the use of a, so called, “antenna tuner.” If you have watched many videos on my channel, you know that I prefer to call them “antenna matching units.” They actually function as an impedance transformer. They transform the impedance of the antenna/feedline combination to 50 Ohms, so the transmitter will see a perfect load and deliver full power into the feedline.
So this trap? It has happened to me. It happened when I was on the phone helping someone troubleshoot, and I couldn’t see their radio. This video will show the trap and hopefully it will save you the frustration of falling into the same trap.
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73, de N4HNH - Наука та технологія
Correct. If you tune with the internal tuner on an antenna, the radio is matching that antenna. If you change the antenna or switch into a dummy-load, your circuit is still expecting to having to match the antenna it was tuned with. So yes, you must disable the internal tuner specially if you are on a 50ohm dummy load. Is easy to "forget" the tuner on.
Thanks for passing down the trap so others won't fall into it.
It fooled me once. Not again.
Never know about the dummy load with “tune on” trap. Now I do . TNX agn and great info
Hi Doug! I was troubleshooting over the phone with a person who thought that their new antenna was defective. It was supposed to be resonant on several bands. As a troubleshooting step, I asked him to transmit into his dummy load. I wanted to verify no issue with the coax. Still high SWR but slightly different high SWR. I asked if he had the antenna tuner on, or not, and he said no. That threw me off. In the end the ATU was, in fact, enabled. He had used it with his previous antenna on that particular band stack register, and the radio remembered it. The radio recalled the parameters for his previous antenna, thus his radio’s output impedance was not 50 Ohms. 73, Doug
Thank you.
You’re welcome!
Awesome!! 👍👍👍
I’m glad you liked it.
When I started out in this hobby, so-called antenna tuners were called the "transmatch." It's much more descriptive of what the device really does.
Yep! I preach that. That’s why I put “antenna tuner” in quotes. I wrote about it in the video description. But it’s another example of the manufacturers making what we will buy. Newer isn’t always better. But today’s lesser informed buyers are drawn to colorful displays and buzzwords, like SDR, waterfall, and antenna tuner. So the manufacturers make what they think we will buy. We started accepting internal “antenna tuners” that can only match up to a 3:1 mismatch, so that’s what we get now. I call them “touch-up tuners.”
Thanks for the informative videos.
At the 2:20 mark you click 'tune' on the video monitor - is that a separate external tuner controlled by the software?
The Tune option in WSJT-X is used to test your FT8 or FT4 output. It has nothing to do with the antenna. I’m just clicking it to enable transmit.
I own a signal stick now because of this radio! haha
Please tell us more.
I have the ic705 and TX500. Both have an SWR sweep feature… I really only operate POTA using a buddipole so tuning the antenna is critical. I wish the radio had a swr sweep. And also the ability to access the function button with the mouse. That’s not possible right? WY7WL
I have sent my request for that and other mouse functions via the Yaesu Contact Us page. I organized a letter writing campaign among my Patreon team.
Thank you.. Same issue with an amplifier. Tune off!.
Absolutely don’t tune with the amp enabled. I use 20W because that is the recommended tune power for my ATU. But I only tune once per band, every 25kHz, so the ATU can record the match into its memory. I call it “Train Your Tuner.” After that, the ATU tracks my band/frequency changes.
What happens to the tuner as the frequency is changed? Does it remain on the matched reading of the most previous tuned frequency? Thank you!
It depends upon the auto-tuner design. Some ATUs track the VFO during receive. Some return to the last match parameter used for the band you switched to. Once you transmit, the ATU detects the frequency and recalls a more precise match, assuming that a more precise match was previously stored in memory.
It happened to me by using SG-230 antenna tuner. Forgot to disable antenna match on my FTdx-10, and wondering why SG-230 struggling to tune.
It happens to the best of us. That’s why I shot the video.
Are you using a special type of monitor with the FTdx10? I would love to hook one up to my FT-710 but I wasn’t sure it would be able to do it
My monitor is an LG 20.5” with a DVI-D type connection. The output of the FT-710 AESS is also DVI-D. It has extra protection, related to the connection of an external monitor, that the FTdx10 doesn’t have. I get into that at schematic level over on my Patreon portal.
If you want to try a monitor/adapter combination, I still recommend doing it before the warranty period for your radio has expired.
@@n4hnhradio would a DVI-D to HDMI adaptor work to do this on a monitor or TV without DVI-D or would this cause issues with the hardware internally?
There are many discussions about using adapters. Some have caused the DVI-D port to fail, requiring a trip back to Yaesu for repair. In some cases, the entire main board had to be replaced. That costs approximately $800, if your radio is out of warranty. We have an entire discussion about it over on my Patreon portal.
Would this effect occur changing bands? Where you would have to re tune with every band change?
Never have the “antenna tuner” enabled when transmitting into a dummy load. The dummy load is already at 50 Ohms impedance. Tje “antenna tuner”, once “trained”, should recall the match parameters when you change bands. If you never want to touch a Tune button again, watch my videos about Ultimate Automation.
I was thinking more like when WSJTX is setup to autotune on band changes where the watch dog timer may change the bands in the middle of a tune up. @@n4hnhradio
So no need to buy an external antenna tuner with this radio? Thanks for the video!
That depends on your antenna. Most internal antenna matching units cannot match more than a 3:1 SWR. That’s not what the video is about.
Make sure you push the PPT when you transmit,,,,,,,,,, next
What is a PPT?
I would rcomend you read Walter Maxwell’s book Refections. Chapter 17 in the book provides a good summary. He explains how tuners/trans matches really work. Bottom line is they do help the antenna resonate delivering more power into and out of the antenna. I ran some WSPR tests on a random wire (no transformer) antenna with an antenna tuner and that antenna performs as well if not better than both a 1/4 wave vertical and an ended half wave I have.
I don’t need to read that. I use a doublet antenna system. I know all too well how a transmatch works. The radio delivers more power when the match looks good. That isn’t the point of this video.
@@n4hnhradio a lot of people hear an antenna tuner doesn’t tune the antenna and they think it doesn’t really do anything to help the antenna perform
An “antenna tuner” doesn’t tune the antenna. That’s just the reality of it. The “antenna tuner” acts as a type of transformer, to convert the complex impedance of the antenna system to an acceptable 50 Ohms, so the transmitter will deliver full power into the feedline. There will still be loss in the feedline, but there is more power to start with because the transmitter was satisfied that it had a 50-Ohm load to transmit into. Thus the antenna ends up with more power to radiate.
Some people get too hung up about SWR. There is no perceptible difference between a 1.1:1 and a 1.5:1 SWR. Even a 2:1 is okay as long as the transmitter can handle it. That’s why hams of old were happy with a 2:1 SWR. Louis Varney, G5RV, was seeking an antenna that would yield a 2:1 SWR on the 20m band and fit within the limited space of his garden. His tube type transmitter didn’t care. It delivered full power to the feedline.
I hear people brag about their 1.05:1 SWR and I chuckle. Move up or down the band a bit on 40, 60, 80, or 160 meters and that 1.05:1 can become 1.7:1 or more. But those on the receiving end won’t be able to perceive the change.
@@n4hnhradioI agree 100%. I was just having that exact conversation with a fellow club member two days ago. 1.5:1 is only a 4% loss. What I’m talking about is there common misperception in ham radio community that feel tuners don’t help. They do. A random wire antenna with wildly high SWR if trans matched (“tuned”) will perform as well as a resonate antenna.
Yes, the doublet antenna system requires an antenna match (the term I prefer). I did adjust the length of my ladder line so a low SWR happens on the 17m band. When I first erected it, the lowest SWR was at 15.5MHz. I shortened the ladder line and let it settle at approximately 18.135. But for all other bands, I need the antenna matching unit.
Fortunately the loss in a balanced feedline is minimal. That makes the doublet antenna system very desirable if we must run a long length of feedline. The ladder line helps minimize the loss.
Another video you might want to do is with a manual tuner you can get swr down to 1:1with 2 different settings of the manual tuner this is why I make a crib sheet of settings but use either an antenna analyser or similar device . Also avoid a negative swr the Dr once covered this in QST then following few months later RSGB copied it in Radcom changing the wording slightly. ❤ the channel de M0JFE
I have a manual tuner. It works very well. It’s a MFJ-989C. I’ve had it since the 1990s. But I only use it as a backup now. My Palstar AT-Auto could tune down to 1.05:1. A 1:1 SWR is over-rated. Anyone listening to you can’t tell the difference between a 1:1 and a 1.5:1.
I have yet to use the tuner...i use my rig for POTA and make sure the antenna(s) are good via my Rig Expert before hooking up..I cant seem to like FT modes..not for lack of trying...but I'd rather do CW...FT modes to me are a tiring waste of time and boring as He**.
I use tuned antennas for portable operation as well. Either a linked dipole or a portable EFHW from NY4GEFHW.com, as seen in my SOTA playlist videos. It is best to not need an antenna matching unit.
I prefer CW as well. I like SSB too. I only work FT8 for Patreon team members. I wrote a configuration document for them, and that required months of research, sorting through all the misinformation related to the subject, and writing a concise “how to” document.
@@n4hnhradio you do an excellent job.
Thank you!
@@n4hnhradio a guy I know just won in the Olympics of HR. VE3DZ...and his team mate. It will be interesting to hear his stories next month when I see him.
Same issue with an amplifier. Tune off!
I assume you are referring to an amplifier with an integrated ATU. I use an amplifier with an integrated ATU. But it is a solid-state amplifier, thus I don’t need to tune it into a dummy load.
With a tube type amplifier, it’s best to tune into a dummy load first, with any type of “antenna tuner” disabled. Then switch to the antenna. Enable the “antenna tuner” and ensure that you have a good match. Then, if the resultant SWR is much higher than the 1.05:1 or so of the dummy load, move to a clear frequency and touch up the amplifier tuning.