How to Use an SWR Meter: standing wave ratio meter - guidelines & tips
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- čas přidán 29. 06. 2024
- Standing wave ratio can be very important when using a transmitter. If the level of standing waves is too high then it can either damage the transmitter or transceiver output, or cause it to reduce its power. So measuring the SWR is important. Knowing how to use an SWR meter and connect it up can be vital and it is described in this video along with some key hints and tips on how to use the SWR meter and gat the best from it.
SWR bridges or SWR meters come in many forms. They don’t have to cost too much, although higher price ones do give better performance and they can measure more parameters like power levels.
The video describes how to connect the SWR meter into the feeder and then how to use it making sure that no undue interference is caused.
The video also describes the various points where SWR meters can be sued and their advantages and disadvantages. It also describes how to use the SWR meter when an ATU is present.
Another interesting points is the feeder loss and know how this affects the SWR readings. High feeder loss can make an antenna with a high SWR look much better, so it gives guidance on this. The video also gives a few useful bonus tips on how to use the SWR meter as well.
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Thanks from the other side of the pond. This video is exactly what I was looking for.
Glad it helped
Thanks from the USA. Cheers to you.
Thank you too!
Thank you for the video!
Glad it was helpful!
Great video! Thank you!
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Thanks for the tutorial.
Glad you found it useful.
A useful video for beginners
Glad you think so!
Useful, thanks.
I am glad it was helpful.
thanks for the video info
Glad you found it useful.
Excellent explanation, Thanks for the nice upload, Regards from VU2XFD, #Ascertain
Thanks for your comment - really glad you found it useful.
Wow EXCELLENT VIDEO, I subscribed! Yes I admit that I'm a long time CB guy. But this was very important and thorough! Thanks from the U.S. God Bless..
Really glad you found the video useful. Thanks very much for the comment.
It would be a lot more thorough if the whole process of reflected power was explained
Great video! Excellent!!! Thank you!
Really glad you liked the video.
Thank you
Glad you found the video useful.
This is an excellent guide on how to use a SWR meter designed for 25-30mhz on 20 meters,
being as the generated frequency is so far out of the meters designed operating range I
would trust the readings as much as i would trust a chocolate teapot.
For any new person getting in to Amatuer Radio make sure the SWR meter covers the bands
you want to use it on.
Yes, point taken, but in general the type of meter used would have been adequate for a demonstration. Also the main issue is the sensitivity which was proved to be quite adequate. That said the lower end meters are generally not that accurate but are able to provide an indication of whether there is a high or low SWR.
Hi can you please help me understand what’s wrong with my readings?
Cb radio built in swr meter shows low swr.
Connected external meter, now both the external and internal meters shows high swr.
Adjusting the antenna until both the external and internal meters matched with a low swr.
Unplugged the external meter, now the internal meter suddenly shows high swr.
@@daienaa This type of SWR meter is reading voltage nodes and can be sensitive to where along the feedline it is placed. Adding a few feet or meters of coax changes the "node" or position of maximum reflected voltage. The short patch coax needed to insert an external SWR meter also has the effect of changing the total feedline length and thus moves the "node".
ANYWAY, if your antenna is not balanced, the feedline coax itself becomes part of the antenna and its length *matters* . Adding ferrites at the antenna end will mostly stop that phenomenon and then your SWR won't depend so much on the length of the coax.
@@thomasmaughan4798 Thank you so much for explaining. But what is the point with using a swr meter if it’s so unreliable that just adding the coax from the radio to the meter will affect the reading and putting it back on radio, the swr will change once again from the external reading. Say if I had a older radio with no swr protection and no built in swr meter, I would connect the external and test, the result is inaccurate and I would think everything is alright and remove the external meter (and coax of course) and will damage the radio because I trusted the external swr meter?
@@daienaa That's simply the nature of the beast. Adding an SWR meter inline on the feedline, if by so doing you change the length of the feedline, you really are not testing the "system" as you intend to use it UNLESS the SWR meter stays right there ALWAYS, which for me is exactly the case. The feedline becomes part of the system and its length MATTERS *if* you have standing waves (if not, the length does not matter).
BUT if the antenna is mis-matched (and most are to some degree) then you are going to have "standing waves" which is simply the voltage peaks of the outgoing radio waves happening to meet the reflected radio waves and every quarter wavelength along the coax you are going to have a "node" where these voltages add up (that's bad) and anti-nodes where they cancel and if you measured at that exact point, you would see nothing! No voltage (in the case of infinite SWR). How weird is that? This is why built-in SWR meters almost never read the same SWR as external UNLESS you have a perfectly matched antenna and there aren't any standing waves anywhere. It is also why I trust the built-in SWR meter because it sees the SWR that the transmitter actually sees, and that's what matters most.
A reasonably reliable method is to connect the SWR meter using exactly 1/2 wavelength of coax between the SWR meter and the transmitter. So at 20 meters (14 MHz) you would use 10 meters of coax BUT BEWARE the velocity factor of 65 percent or so, in other words, 6.5 meters of coax will ensure that the external SWR meter is at the same "node" as the transmitter.
I wish you'd talked more about the cross-needle type meter.
Apologies - but I was trying to keep the video as short as possible.
it simply gives both fwd and reflected power at the same time, one needle for each. no need to switch or calibrate.
Where the needles cross, is the SWR reading.
I am getting an swr for my tube sonar sf-23 radio Does anyone know which one I should get?
So to clarify, right before you move the switch from FWD to REF, do you "un-key" the mic, and then "re-key" it once you've moved the switch to REF? Or do you keep the mic keyed continuously during the switching? Or, does it matter one way or the other?
It should not matter because you are only switching a sense line and not directly any level of power.
My SWR meter is built into the CB how do you use the cal. to find the SWR I have been out of cb many years late 60s and don't remember much about "how to " anything.
It all depend on the CB radio. It is possible that it calculates the SWR automatically using the internal processor if there is one - often there will be a position for forward and reverse powers, but check the manual.
Hi can you advise me please my swr meter is going into the red high swr but the swr meter on the radio is reading just over 1. I think my meter might be ify I have had it for years. Regards
David Cooke - I see this is an old comment. Don’t know if you ever did receive an answer to your question, or not. Your situation can be difficult to answer. And without additional testing, I’m not sure anyone could help via a return comment. Based on my previous experience, I would probably put more trust in the external meter. But the best thing would be to somehow use another meter (borrow one, perhaps?) to confirm what you are seeing. I’ve found internal meters in any one given radio to be marginally accurate. I trust them only as far as giving me a rough idea.
And what about the SWR scale in older rigs like Icom 735? Is it a reliable way to measure or should I get a proper SWR meter anyway? I’m a newbie :)
I haven't looked at the accuracy of the Icom 735 meter, but I am sure it is more than good enough for what you need. The meter dials in the external SWR meters have much larger scales and are easier to read, but when looking at the difference between 1.5:1 and 2:1 or 3:1, for example, the IC735 should be more than good enough. You don't need to spend ages getting the SWR down the last fraction. The main reason for monitoring the SWR is to make sure the PA in the 735 is not being subject to very high levels of SWR get it down to 2:1 or preferably 1.5:1 and this is more than good enough. The internal meter will be more than good enough for this. Hope this helps.
I have a 735. It's a great old radio and still works well. The purpose of its built-in SWR is to protect the transmitter from excessive voltage on the final amplifier transistors. Reflected power, or more specifically reflected voltage, ADDS to the voltage already there and a high SWR situation can then exceed the voltage rating of the transistor. The 735 is designed to instantly reduce power in that circumstance (as are all modern radios) but it might not be fast enough in the case you completely forgot to attach the antenna.
As you can see, a perfect 1:1 SWR might still not be radiating anything out the antenna; a dummy load should always show perfect SWR.
does having a good SWR significantly affect reception as much as it does transmission?
There is a loss as a result of not having a good VSWR, but this can be relatively small. For transmitting, this can be more of a problem as most modern transceivers will detect the VSWR and if it rises, they will reduce the power output to prevent damage. This combined with the loss in signal as a result of the VSWR will mean the overall radiated power is reduced and the signal will not be as strong as others. This will reduce the competitiveness of the signal if used for things like amateur radio, etc. For other applications it can mean the signal is reduced and detected over a smaller range, etc
@@ElectronicsNotes how would you explain the efficiency of a doublet antenna with swr of over 10.1 with very little power loss
@@Pioneer936 SWR is not itself a serious problem. Consider a big reflection coming back to the transmitter. What happens? Well, it reflects back to the antenna! Then back to the radio. It might bounce 10 times before finally radiating enough to not be measurable. Assuming zero loss in the feedline, ALL power sent by the transmitter MUST go out the antenna -- eventually! It might take several or ten bounces to finally radiate and a Zepp antenna seems to work pretty much exactly that way.
A lossy coax cable might convert from 1 to 3 db (up to half the power) to HEAT on each bounce.
So all power transmitted must either be radiated OR converted to heat in the coax (or a blend of these).
We see therefore that the problem of SWR depends on the loss in the feedline. Reduce feedline loss (ladder line has nearly zero loss) and who cares about SWR? But the transmitter also cares because reflected voltage adds to transmitter final amplifier voltage. So you can have a HUGE SWR at the *tuner* so long as you keep the reflections out of the transmitter.
Can we modify it to work at around 100MHz?
As the basic design for a particular item will be focused on a particular band, it is not normal to extend their frequency range once they are designed and manufactured.
That would be a complete re-design. These meters have internal inductive and capacitive elements whose reactance is likely to be excessive at 100 MHz.
I have a question!! I have a
Selfix no.6702 swr/power meter.
The stickers on the back of the unit
came off and I don't know which
connector is for the antenna and
which one is for the radio!! I don't
want to damage my radio or the
swr meter. Is there any way to
tell which connector is which?
PLEASE HELP!! Thanking you
in advance, Norman.
You won't damage the rig or the SWR meter if you run the power into some form of good match or a dummy load. Connect the system up, keep the power level low. Then see which connectors give give you maximum forward power corresponding to the Forward position on the switch. The SWR meter really does not mind which way round you connect it - the system is labelled so that the forward switch position corresponds to the forward indication. You can reverse the connections, but the maximum indicator would occur on the Reverse switch position. I hope this explains it.
I understand that if you are looking at the meter at front , left side is for the radio , right side is for the antenna !!
Hello! The rear of my meter does not have "ant" and "trans". Mine says "in" and "out". I am unsure which connection is for the antenna and which one is for thew transmitter? Can you help? Thx!
In will need for power coming in from the transmitter, ie connected to the transmitter, and out will similarly be for the power output to the antenna. I hope this helps. If you get it the wrong way round all that happens is that the forward snd reverse positions on the meter appear to be opposite to what they should be. I hope this helps.
Cos my field is in computers and being a semi-pro, i have some idea, , your wondering, what the hell is an SWR, SWR stands for "Standing Wave Ratio", the transmitting signal travels along the antenna (FORWARD) and refects at the end, returning down the antenna (REFECTED), the forward signal interferes with the reflected signal causing constructive or deconstructive interference, differant lengths create differant phases along the antenna, when a peek meets a peek there is max emission, and when a peek meets a trough there is zero emission, an SWR ratio of 1:1 is perfect constructive interference, where the cycle appears STATIONARY on the antenna, creating a perfect waxing and waning electo-magnetic field, as the electric field collapses, the magnetic field increases and vice versa, , ,Without that load absorbing energy, the energy instead appears as a high voltage or high current somewhere which may not be equipped to handle it, ,
So basically, an ideal 1:1 SWR will produce a low 50ohm resistance match where the antenna does work, the SWR is relatively constant along the feedline, the impedance will vary along the line unless it is perfectly terminated (that is, the SWR is 1.0 : 1). This is an important concept for impedance matching, because with a high SWR, the impedance at the final output transistor load inductor could be lower than 50 ohms, and produce a high current that damages the finals, , ,
PS - a 1:1.5 SWR = just a 4% loss \ a 1:2 = 11% loss \ and a 1:3 = 25% loss
if you dont have a reverse switch can you swap the antenna with the transmiter?
Absolutely - but you also need to make sure you get the connections the right way round if you do have a switch.
@@ElectronicsNotes thank you
Sir Bremi liner about plz
My meter won't zero. It swings right in forward and I can calibrate it. When I switch to reflected it stays at 1.3.
It depends what you are doing. If you have RF passing through and you set it to FSD in the forest direction, then when you set it to measure reverse power then that is your SWR.
What one would be good for Alinco DX 10 ?
There are a lot of good SWR meters out there. Provided its frequency range matches your transceiver it should work OK. The DX 10 should also have its own internal metering, but it is often useful to have an external one so SWR can be monitored all the time.
What's the proper way to set the swr for a dual antenna set up? Removing one from the system at a time and calibrating the remaining one or leave them both hooked up and try to balance both at the same time? Thank you.
You may well find that one antenna affects the other. So you will need to set it up with both connected. Set one antenna up for minimum SWR and then the other. You mayweed to go back and do them a couple of times. This is if I read correctly what you are doing.
@@ElectronicsNotes that is exactly what I had thought I would have to do. Just wanted to verify that before I took action. Thank you
A bit funny SWR-Meter for the Examples / Frequencies used in this Video. 05:40 It says, it is for 25 - 30 MHz.
It was probably not right to use the particular SWR meter for 14 MHz, but the design is straightforward and known to operate well over the amateur bands. Sensitivity falls at lower frequencies but OK for 14 MHz.
Since the box is small, the sensing element is short and thus more effective at higher frequencies. Most of this style was made for CB but works fine on ham radio particularly since you can give it enough power to achieve "set" calibration.
At 3.5 MHz, a 4 watt transmitter probably cannot calibrate the meter so dial up the power until you can "set" the calibration. That's a bit rude to have 100 watts of dead carrier but there you go, the meter will work perfectly if you give it enough power.
Is this meter good for ham antennas?
Many SWR meters are suitable - check the frequency response, power handling etc to make sure it is right for your setup.
E. G? You mean I.e? On diagram
You don't mention where the reflected power goes that reaches the tuner
The output transistors/valve have to drive harder to overcome the reflected signal and carry on outputting the correct wave. In essence they have to burn up the reflected energy.
@@markthorne2296 reflected energy is re reflected back to the antenna at the atu, the atu does not absorb energy
Why is 14 MHz called 20mtrs ect .Also these antenna tuners i thought a more relevant name would be a matcher as they dont fix a badly tuned antenna !.
14MHz is the frequency of the band, 20 metres os the wavelength. Accordingly the ham radio band is known by both names 20 metres and 14 MHz.
"Also these antenna tuners i thought a more relevant name would be a matcher"
Then call a tuner a matcher. Others call a matcher a tuner. Very few antennas are designed to be tuned remotely, SteppIR being an example of just such a thing.
Hum? Is this a lead to finding or should I say hacking others freedom of receiving or transmitting an already paid signal. If an individual has not paid for service, then can understand looking for non payer. But if an individual is paying for ex. phone service, then hacking is a violation of protocols.
This has nothing to do with hacking. It is purely a method of measuring a signal you have generated for transmission to see the effectiveness of the transmitting antenna system.
"hacking others freedom of receiving or transmitting an already paid signal."
Yes. These SWR meters can also change the language. The one shown is from China, consequently all of your transmissions will be converted to Chinese language.
I have baaaaad swr :(
That is a shame. Try to improve the match between the antenna and the feeder.
I fixed it since then. I realized I had an N type connector going into the antenna and a pl259 in the radio. I replaced the N type with a pl259 and now I have 1.3:1 swr. All is well, thanks for the video
"I have baaaaad swr"
I have GOOD SWR. I like SWR so much sometimes I leave the antenna disconnected so I can have infinite SWR. It does not get any better!
Get to the point
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