I've finally found some time to use the early VNA which I bought in the Covid lockdown period... and this set of videos is so useful, thank-you! I hadn't thought of using the VNA in conjunction with my antenna matcher but I will now. What a great idea! 👍👍
I have been using an end fed random wire antenna for years with great results. The unun is grounded to a steel window well and I also use a choke on the coax just before it enters the shack. The choke is key since it prevents RF from entering the shack
Thanks for doing this video. I’ve got the same ATU and will be doing the same when my VNA arrives - EFHW is how I usually operate portable so this will make short work of setting the dials for different bands when in the field!
Transmatch + NanoVNA + 5 minutes of knob fiddling = Autotuner. 😀 Kidding aside, it was great to see how all of this works. Much more educational than pushing the TUNE button. Thanks for these NanoVNA videos.
Steve Ellington has some excellent videos on testing and optimizing EFHW antennas. The short and skinny is: 1) inverted-L, 2) balun fairly close to ground, 3) good earthground at balun, 4) choke the crap out of balun at the feedpoint, and 5) no counterpoise. That should provide a little bit better than 3dB improvement over most installions. It will turn a so-so performer into a good performer. Also, usually "A tap" is the full inductor. A general rule for best performance is minimum inductor with high capacitance. It provides the highest Q tuning.
A 49-1 UNUN is what you need, not a BALUN. And I think that this is the first VNA video I've seen that is checking an antenna other than a 2 meter or 70 cm. Thanks
@@davep6977 the air core you are talking are not really efficient, see this page www.karinya.net/g3txq/chokes/ and take a look at this wonderful video of trx bench, now that is a real effective choke that cover all amateur bands and it is quite cheap to build too : czcams.com/video/JhAPJISUjB8/video.html (sorry to plug another youtuber video on someone else page) but I sincerly think it is a great demonstration on how common mode choke work and how to build a really effective one.
Nice video thinking of buying on and looking for a review. You need an unun on an end-fed not a balun. A centre-fed antenna is balanced while coax is unbalanced so a balun, balanced to unbalanced. An end-fed is an unbalanced antenna, so unun.
You cannot just go up or down in a vertical straight line on a smith chart. When you add or remove reactance with capacitors and inductors, you also move left or right. The shortest and ONLY path toward the center of the smith chart is therefore a combination of two curves. For instance, you must go enough left with the capacitor in such fashion that when you finally add inductance, you curve right, back to the center of the chart. See czcams.com/video/Hsx4wqAlqlQ/video.html It's easy to explain visually than in words.
I wonder if the Nano VNA could be used to tune I F strips in a radio, I have used a sweep generator , also a Wobbulator , and my spectrum analyser, I've just bought a Nanovna impressive little tool
in order to take these measurements, you did need to calibrate the device at the end of the tiny peace of coax ? if so, you probably did need to have sma to pl259 adapter, this means the calibration is again wrong because of the adapter ? your you need a calibration set for sma m/f, another one for N m/f and another one for pl259/so239 ??
I'm no expert at this but I do the calibration with everything but the antenna connected to the VNA, if possbile. But I only have the SMA version of the S. O. L. T . so it is just to the end of the tiny coax. Maybe that is good enough??
the radio is disconnected and the VNA takes it's place. you wan to radio to see 50 ohms so if the VNA sees 50ohms then you put the radio back in.. same as an antenna analyzer. The VNA outputs RF (weak transmit) and measures the reflected signal for amplitude and phase.
Question. I have a dual antenna whip nagoya. It has 3.5vhf and 5.5 of gain uhf. If i tune the uhf frequencie tona desire, will the gain dimish or be affected and the vhf .
Been a Ham since the 1970's extra class WAS WAC DXCC. I had an offset dipole on a 4:1 balun that I set band SWR using my HP8921a. Worked great. I though an end fed would fit my yard better. first time using a 9:1 unun. I've got a good ground on the balun. the ground in the garage is not great. although the 4:1 balun system was working fine. I suppose an RF choke would help things. never had to use one before in all my antennas over the years. different data on wound toroids and multi small cores over the coax. I think I will go back to the windom type
I think I found the problem. bad ground connection to the transmatch. I only added it recently. A flea market find. even without an RF choke things are acting normal.
@@IMSAIGuy That's great! I really like Endfed. I do a lot of QRP and live in an HOA restricted area so its end feds for me. I find them easy to put up and tune. I have mine as an inverted L in the attic. Hope to hear you in the air. 73, KF7ZVL. What does IMSAI stand for?
Here is a more basic introduction for newbies that shows the menu options visibly clear: czcams.com/video/QJYeFpiqY8c/video.html This video assumes you already are familiar with the menu.
I've finally found some time to use the early VNA which I bought in the Covid lockdown period... and this set of videos is so useful, thank-you! I hadn't thought of using the VNA in conjunction with my antenna matcher but I will now. What a great idea! 👍👍
I have been using an end fed random wire antenna for years with great results. The unun is grounded to a steel window well and I also use a choke on the coax just before it enters the shack. The choke is key since it prevents RF from entering the shack
The EFHW antenna needs a counterpoise to stop RF on the coax. A common mode choke will also help.
Thanks for doing this video. I’ve got the same ATU and will be doing the same when my VNA arrives - EFHW is how I usually operate portable so this will make short work of setting the dials for different bands when in the field!
Transmatch + NanoVNA + 5 minutes of knob fiddling = Autotuner. 😀
Kidding aside, it was great to see how all of this works. Much more educational than pushing the TUNE button. Thanks for these NanoVNA videos.
there's only so much that an autotuner will be able to handle. those manual boxes have way way bigger tuning range
Steve Ellington has some excellent videos on testing and optimizing EFHW antennas. The short and skinny is: 1) inverted-L, 2) balun fairly close to ground, 3) good earthground at balun, 4) choke the crap out of balun at the feedpoint, and 5) no counterpoise.
That should provide a little bit better than 3dB improvement over most installions. It will turn a so-so performer into a good performer.
Also, usually "A tap" is the full inductor. A general rule for best performance is minimum inductor with high capacitance. It provides the highest Q tuning.
Good idea to use NanoVNA for this. Takes some of the trial and error out of finding correct antenna "tuner" settings for various bands.
A 49-1 UNUN is what you need, not a BALUN. And I think that this is the first VNA video I've seen that is checking an antenna other than a 2 meter or 70 cm. Thanks
Nick Rupp
Are you sure his ant was half wave? And don’t forget about common mode choke.
and by the way, I am sure you already know this but technically, you need the end fed unun + a 1:1 choke for end fed antennas...
add an ugly choke (20 turns of coax around a 4-6 inch pvc pipe) See my qrz page W9DLP
Isn't an endfeds ratio 49/1 ?
@@jamesbradley9233 there are 9:1 also that are quite popular but that one is not a resonant antenna.
@@davep6977 the air core you are talking are not really efficient, see this page www.karinya.net/g3txq/chokes/ and take a look at this wonderful video of trx bench, now that is a real effective choke that cover all amateur bands and it is quite cheap to build too : czcams.com/video/JhAPJISUjB8/video.html (sorry to plug another youtuber video on someone else page) but I sincerly think it is a great demonstration on how common mode choke work and how to build a really effective one.
I made a 9-1 for a random length wire, but an efhw is half wave on the lowest frequency hence the 49/1 I'm building now for this.
Nice video thinking of buying on and looking for a review. You need an unun on an end-fed not a balun. A centre-fed antenna is balanced while coax is unbalanced so a balun, balanced to unbalanced. An end-fed is an unbalanced antenna, so unun.
yes I have a 9:1 unun. I now have tamed the RF return. It was due to a bad ground at the transmatch
Think my unit arrives tomorrow!
Im a bit confused as to why you adjusted the inductor? The smith chart seemed to be on the capacitance side at first
You cannot just go up or down in a vertical straight line on a smith chart. When you add or remove reactance with capacitors and inductors, you also move left or right. The shortest and ONLY path toward the center of the smith chart is therefore a combination of two curves. For instance, you must go enough left with the capacitor in such fashion that when you finally add inductance, you curve right, back to the center of the chart.
See czcams.com/video/Hsx4wqAlqlQ/video.html It's easy to explain visually than in words.
I don't recall seeing how you connected the VNA to the antenna.
antenna connected to antenna connector of transmatch
VNA connected to radio connector of transmatch
you wan the radio to see 50 ohms.
You are very funny :)
I wonder if the Nano VNA could be used to tune I F strips in a radio, I have used a sweep generator , also a Wobbulator , and my spectrum analyser, I've just bought a Nanovna impressive little tool
should work fine
in order to take these measurements, you did need to calibrate the device at the end of the tiny peace of coax ? if so, you probably did need to have sma to pl259 adapter, this means the calibration is again wrong because of the adapter ? your you need a calibration set for sma m/f, another one for N m/f and another one for pl259/so239 ??
I'm no expert at this but I do the calibration with everything but the antenna connected to the VNA, if possbile. But I only have the SMA version of the S. O. L. T . so it is just to the end of the tiny coax. Maybe that is good enough??
So what exactly is the vna connected to in back of the matching unit, the transmitter connection? I assume the antenna is connected also.
the radio is disconnected and the VNA takes it's place. you wan to radio to see 50 ohms so if the VNA sees 50ohms then you put the radio back in.. same as an antenna analyzer. The VNA outputs RF (weak transmit) and measures the reflected signal for amplitude and phase.
Thanks for the informative video. Curious about what you are using as a stylus. My fat fingers can’t pick the right thing sometimes.
Where the tuner device connected ?
the tuner is between the antenna and the NanoVNA
Question. I have a dual antenna whip nagoya. It has 3.5vhf and 5.5 of gain uhf. If i tune the uhf frequencie tona desire, will the gain dimish or be affected and the vhf .
Probably. It depends on the design of the antenna.
@@IMSAIGuy well it it not fiber glass or dipole or commet antenna is just stell whip antenna Nagoya
@@SuAmigoElilegal I would guess it has a loading inductor and possible capacitor at the base.
what is the model number
@@IMSAIGuy Nagoya NMO-200A 38.5" Antenna
How long have you been a ham? End fed use the coax as the other side if the dipole? Use a longer piece of coax and ground your equipment.
Been a Ham since the 1970's extra class WAS WAC DXCC. I had an offset dipole on a 4:1 balun that I set band SWR using my HP8921a. Worked great. I though an end fed would fit my yard better. first time using a 9:1 unun. I've got a good ground on the balun. the ground in the garage is not great. although the 4:1 balun system was working fine. I suppose an RF choke would help things. never had to use one before in all my antennas over the years. different data on wound toroids and multi small cores over the coax. I think I will go back to the windom type
I think I found the problem. bad ground connection to the transmatch. I only added it recently. A flea market find. even without an RF choke things are acting normal.
@@IMSAIGuy That's great! I really like Endfed. I do a lot of QRP and live in an HOA restricted area so its end feds for me. I find them easy to put up and tune. I have mine as an inverted L in the attic. Hope to hear you in the air. 73, KF7ZVL. What does IMSAI stand for?
@@kelley64 IMS Associates, Inc.
Well, excuse me !
Good introduction, could be great if you weren't poking at a screen with so much glare that we couldn't see what you are doing
Here is a more basic introduction for newbies that shows the menu options visibly clear:
czcams.com/video/QJYeFpiqY8c/video.html
This video assumes you already are familiar with the menu.
Lefter?? 😂
WAAAAAaaa too confusing!
Start here for intuitive clarity:
czcams.com/video/QJYeFpiqY8c/video.html