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Ultralight SWR indicator?


#1

I’m looking for a simple, ultralight, swr indicator for use with my MTR5B so I know I’m presenting a reasonable SWR to the little rig. I’d appreciate suggestions.

Thanks & 73, Barry N1EU


#2

From qrpkits.com http://www.qrpkits.com/swrind_case.html. qrpguys.com also makes a similar one that is a few dollars cheaper (but I can’t get a url directly to that page).
Also http://www.qrpkits.com/ezseries.html#ezswr

I have the one from qrpguys, which I use when tuning up my loop antenna with my MTR3B. I’m quite happy with it.


#3

Thanks! Those are definitely along the lines of what I’m looking for although I wish they would have a few more LEDs and indicate absolute SWR reading rather than depending on relative dimness of a single LED to indicate a match. When operating in direct sunlight, seems like it might be a challenge to judge relative dimness.

73, Barry N1EU


#4

From my experience, using the qrpguys indicator and a BLT tuner, its pretty easy to see when the LED is the dimmest, especially if it goes out. For the few moments it takes to find a match, I can usually find some way to shade the LED for easier viewing. I think they all use ultra-bright LEDs for that reason.


#5

The TinySWR circuit (with 3 LEDs) developed by Martin DK3IT will meet exactly this need.
Stay tuned, Martin is busy at the moment and will inform us at the next opportunity.

Edit 26/08/2017
The TinySWR is an inline meter (using a Bruene Directional Coupler) and the size of the pcb will be approx. 2.3x2.3 cm
Martin will post all the details and photos Monday, 29/08/2017


#6

Hi
What about https://www.youtube.com/watch?v=ltZLxdEteBY
or
https://www.youtube.com/watch?v=NjHyXi1SrZs ?

It can’t be simpler… :slight_smile:
73


#7

Thanks and understood. Bear in mind, I won’t be turning a knob on a tuner to find a match while looking at the LED. I’m going to be adjusting the length of an EFHW wire for a good match so I must step away for a few minutes and come back and look at the LED again and figure out if it’s dimmer. Just wondering if there’s a slightly more elegant product out there than the single dimming LED indicators :wink:

To put it another way, I’d like to know at a glance whether I’m under 2:1 and I think that would be hard to know looking at a single dimming LED. But I might not have a choice if I want to keep it ultralight.

Barry N1EU


#8

Heinz, do you have any more info, link, photo, etc?

Thanks!


#9

You have even a better option: http://www.sotabeams.co.uk/swr-power-indicator-kit/

This will fulfill your requirements, letting you know your antenna’s swr by beeps/per second!

I have one and I love it… :slight_smile:

73 and GL de Pedro, CT1DBS


#10

Thanks Pedro. The simple LED indicators in youtube are a little too simple and the sotabeams unit is much heavier than I want to carry.


#11

Why, most people have a wire that they pre-cut to a sensible length and then they use an EFHW tuner for the last minute on-site fine tune. Something like this:
http://www.qsl.net/w6dps/EFHW.html

Colin G8TMV


#12

Not sure about “most” people, but I don’t use a tuner.

Anyway, I’m still interested in any suggestions on ultralight SWR indicators, especially those that give some indication of absolute SWR value (or at least confirm absolutely that SWR is under 2:1), and don’t simply depend on dimming a single LED to indicate resonance.

Thanks & 73,
Barry N1EU


#13

Hi Barry,
here is mine solution: http://www.qsl.net/om3cug/swr/swr.htm
Use google translate, please.

73 Igor OM3CUG


#14

See Edit in my post above.


#15

Nice job Igor! Thanks for the update Heinz, I look forward to the info.


#16

But I’m assuming you do use some sort of impedance matching device - why not make the capacitor a variable so you can save messing with the length of the wire?

Colin G8TMV


#17

Hi Barry,
funny to see you thoughts as that was exactly the same reasoning I did to protect my MTR rig some time ago.
As for you, I find disgusting trusting on the brightness of a single led. I prefer to avoid adding a variable capacitor for fine tuning as well, so I built a single analog meter (NoGaWatt). Here a couple pictures:

You can easily get the kit in US amd details of parts and schematic as provided in this page:
http://www.nogaqrp.org/projects/NOGAwatt/nogawatt-kitinfo.html

I think they currently don’t have the panel meters anymore (just check with them), but the parts and PCB; you should add your own panel Meter. The bad news is it’s not easy to find small and light panel meters nowadays but maybe on the States you can find dealers…

My version with a single panel meter plus the toggle switch to select Forward Pwr/ Reverse (then SWR) weights 90 gram (3,17 ounces), is it light enough?
If not, you can get rid of the plastic box and put something lighter…

It would be interesting to change the panel meter and put 3 leds instead… Look forward to get details as announced by Heinz [quote=“HB9BCB, post:5, topic:15859”]
TinySWR circuit (with 3 LEDs) developed by Martin DK3IT
[/quote]

Hope it helps, VY 73 de Ignacio


#18

The circuit of the TinySWR by Martin DK3IT is a refinement of the SWR indicator used by DF3OS and SP5JNW in their QRP ATUs:
http://www.sp5jnw.sem.pl/konstrukcje/atudf3oshtm/atudf3oseng.pdf

Pro memoria: Martin DK3IT will post a detailed description of his TinySWR on Monday, 28/08/2017


#19

Nice job Ignacio! But as you say, those meters are very difficult to find.

Look forward to Martin’s post tomorrow.

73, Barry N1EU


#20

Hi Heinz, all:
Yes, I recently designed a PCB for a super-small and simple SWR indicator. The circuit is based on a design by Hans Steinort (DF3OS),
see http://www.sp5jnw.sem.pl/konstrukcje/atudf3oshtmatudf3oseng.pdf,
with improvements from Dieter Engels (DJ6TE) and
Hannes Hiller (DL9SCO).

I will post more details shortly. Basically, you have a Bruene directional coupler with a resistive divider instead of the capacitative in the original coupler and an array of LEDs that start to glow at increasing voltage levels. This can be achieved by either adding additional LEDs of varying colors, or Zener diodes.

I have been using the very same circuit in various QRP rigs, namely my Rockmite and MTRs and it works pretty well.

I will put the PCB files up on Github and OSH Park so that you can order your own boards, but please allow for one more week or so. I am still in search of the best LED types and combination or Zener values.

Attached, please find a few pictures.

73 de Martin, DK3IT