CB and Ham Radio Techs Love Their Bird Wattmeters

[joeqsmith]

Because we can, at least with my software, lets try to shove a 500M PAM4 signal down this UHF adapter mess.   Yea, get that may be some voodoo math there for the hams and they may not feel that the VNA can measure time domain signals like this.  But hey, I did make a video demonstrating it with various DUTs and comparing it with my scope.  Hams should be up on their basic digital comm stuff by now anyways.

[joeqsmith]

From RS website, 50' of RG58U at 500MHz has a loss of 1.17dB.   But wait, that doesn't consider any of these UHF connectors in the mix.  How much loss is there with our setup?  Looks like about as much as 50' of coax.   

Yellow: calibrated thru
Violet: UHF adapter setup
Red: coax + adapters

https://us.rs-online.com/m/d/b6728848b37672a49202d050a0ff49b5.pdf

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Missed the attachment.

[joeqsmith]

If I were trying to make an accurate Watt meter,  I would start with a high directivity coupler.   Then I would use good connectors, cables.... With my homemade Watt/VSWR meter,  the upper end was only 50MHz.   Building a decent coupler wasn't too difficult and end results were reasonable.   Note that my use of N connectors for this meter was really driven by what I am setup for.  All of my test equipment, power attenuators, cables and amplifiers are N.  The only thing I own with the 1930's UHF connector is a very old Drake TR-4 and a Mars VSWR meter.   Oh, right, there is that crap Nissei RS-70 SWR/Watt meter I bought for the fun of it that doesn't work.     

[joeqsmith]

There was a mistake in the first test which I have now corrected.

https://www.eevblog.com/forum/rf-microwave/cb-and-ham-radio-techs-love-their-bird-wattmeters/msg5100693/#msg5100693

With the VNA now set correctly, I zoomed into the same area that your friend shows.  What do you know, we get very similar data as we should.  So again, I am suggesting that your friends poor performance VNA led him down the wrong path.   Had he had some idea of how this feature worked and what the limitations were, I'm sure he wouldn't have used it as a metric.    Feel free to provide him with a link.

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Forum is still having problems with photo attachments.  The correct photo was renamed and reloaded. 

[joeqsmith]

Upfront, it's a really poor measurement.  DUT is a SNA-N, N-UHF, UHF-UHF, UHF-N, N-SMA, Terminator.    First S11 was measured directly with the LiteVNA from 50k to 8G.  Same calibration as before.     Next, the frequency extender was used to measure S11 from 8-12GHz.   I don't have any sort of coaxial standards that will work at these frequencies.  So, I am using the same supplied standards and my sorted load, again with the ideal model.  I did say it was a poor measurement.

Next I concatenate the two Touchstone files to form a single 50k-12GHz file.   Notice now when we look at the TDR, we are starting to see something a bit more square where we transition to the UHF connectors.   

Something like this would be a better tool: 
https://www.ebay.com/itm/364477680032

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The Touchstone import function in my software needed some improvements.  I'll release 4.03 soon.  This is the same Touchstone file but shown with the cursors active.  We can see it measures roughly 41.6mm where the UHF section dips.    Interesting enough, this seems to be the distance between the two ends.   I'm not sure what these look like inside but I bet the N to UHF transition happens very close to that area.   

[joeqsmith]

Looks like your friend IZ2UUF does have an open area on Youtube.  Looks like the last two videos could have been photo shoots for BD139.   

https://www.youtube.com/@Iz2uufNet

[Kartika]

Hi to all.. reason comes first. I'm looking for a bird 43 meter movement 30uA . any good price? thank you in advance BR

[xrunner]

Hi to all.. reason comes first. I'm looking for a bird 43 meter movement 30uA . any good price? thank you in advance BR

Well the meter is for sale on Ebay for $50 to $100, but don't know if they'll ship to Croatia. Is it for your own meter? If so, what happened to the meter movement - I'd been told these Birds were rugged beasts.

[xrunner]

Yep still working on the project. Had a bunch of other stuff come up I had to deal with.

I need to remove about 12 mm or so from the M3x55 mm bolts I was able to find which secure the top and bottom of the case. Just a bit too long. I'll use a Dremel with a cut-off wheel for that.

I also got back to the semi-rigid coax fun. Shouldn't take too much more work.

[joeqsmith]

I have a set of wire cutters / strippers that includes bolt cutters for smaller English threads.  The work good for soft steel and brass hardware.  For metric, I thread on a nut, make the cut, grind the thread and back out the nut to chase the thread.   No need for all that with the cutters.   

[xrunner]

For metric, I thread on a nut, make the cut, grind the thread and back out the nut to chase the thread.   No need for all that with the cutters.

And that is exactly what I'm going to do. I could buy a cutter for metric - hey yea that'll give me an excuse to start another Amazon order. 

Side issues at home, or why I am constantly distracted from projects?

For example, my "office" chair that I sit in writing this post has been squeaking for months as I rock back. It's annoying as Hell and I finally got fed up wit it this morning. I had tried to oil it a while back but whatever was squeaking inside the mechanism wasn't affected by the oil. I even squirted WD-40 inside the mechanism and it didn't hit the problem.

So I got serious and just took the whole damn chair apart to get the mechanism underneath completely off so I could take it in the garage and deal with it. If you don't know it's a Royal Pain to pound off that air piston that is simply stuck on the chair by interference fit. I oiled every single place that could possible move, put it all back together, and that's one problem solved.

Another issue was the neighbor behind me had big Macaw parrots that I've seen before being carried around outside, but they were kept inside most of the time. About a month ago I kept hearing nasty loud cries and screams like someone was being tortured with a red hot piece of rebar. Wait WTF - that's the natural noise the Macaws make! I finally looked back there and she had placed them in a huge outside cage and that's where they were residing 24/7. I called animal control and I reported it, had to keep a log of the noise while they sent a letter to her to explain what she's going to do about it and see what happens. The letter did the trick so that issue is gone.

End of side issues

Now you see how it goes over here! 

[A.Z.]

use the macaws squawks and the chair creaks as "high SWR" and "overload" alert sounds in the meter

[xrunner]

use the macaws squawks and the chair creaks as "high SWR" and "overload" alert sounds in the meter

I knew you could come up with a good idea I could use, given enough time. 

[xrunner]

Finished the semi-rigid installation. I know it's over-kill, but damn, it sure looks good. 

[joeqsmith]

Nice to see you making some progress.    For the forward, had you moved the attenuator to the coupler, could you just use a simple 90 deg bend?  Is the coax rated for that tight of a bend radius? 

[xrunner]

Nice to see you making some progress.   

Yea had some side projects come up, like refurbishing a couple of solar rechargeable LED yard lights with new batteries. They weren't designed to be maintained meaning they were sealed. But I managed to open them up and kept a few things out of the landfill.

For the forward, had you moved the attenuator to the coupler, could you just use a simple 90 deg bend?

Perhaps, but the attenuator wouldn't fit there due to it interfering with the input connector of the log amp right below it.

Is the coax rated for that tight of a bend radius?

Yes. I knew whatever I did would be scrutinized so I thought about that and all the ways I could bend the cable to get it in there. From what I found this cable (RG-402) can take a 1/4" radius bend. So I'm close to that. Of course there are other ways to make up the two cables but it's functional and looks good.

Sometimes I almost convince myself I actually know what I'm doing. 

[joeqsmith]

Is the plan to still build the second one?  Assuming you are happy with the performance of this one?   

When do we get to see the new face plate?

[F4IUJ]

Good engineering is often about getting good enough with just enough resources (time, money, skills, materials etc...). Most of the time the right solution is not the purest one from a scientist point of view but a good balance between practicality, performance and cost. Hams are amateur who do radio for fun in their spare time, 99% of them (made up statistic!) doing UHF are happy chatting to their friend through the local repeater or playing with tropospheric propagation. I can't see how a fraction of a dB is going to change anything for those who use ready made transceivers. And the not perfect adaptation might just be relevant for those maintaining repeaters.

Personally, I don't particularly like these PL/SO connectors, my QRP stuff uses BNC (good enough and very practical in the field for low power HF) and the rest is a mess due to varying manufacturers preferences... I am not an EE engineer, I do structures for a living but I enjoy my time in the shack fettling circuits of a dubious nature measured with tools of a dubious precision and that what matters to me!

73 de F4IUJ dit dit ;-)

[xrunner]

Is the plan to still build the second one?  Assuming you are happy with the performance of this one?   

Probably. I can use lessons learned and suggestions from this version for the next one such as what A.Z. said -

 

use the macaws squawks and the chair creaks as "high SWR" and "overload" alert sounds in the meter

I can incorporate the Macaw screams like this -

"Hey xrunner that pwr/swr meter you built me was screaming bloody murder at me yesterday, what does it mean?" 

"Oh that? Yea it means one of two things:

A. The meter is lonely because it misses you and it's screaming out for your attention. Go to it and pet it until it stops.

or

B. Your system SWR is above 3.0, investigate the problem and check until it stops screaming"

"Thanks xrunner it sure is a sweet meter!"

When do we get to see the new face plate?

Soon. I need to get to work on them next.

Here's what I need to do:

1. Design front and rear faceplates in Fusion 360 and 3D print
2. Get it all wired up.
3. Make a couple of jumpers to connect RF in and out of the directional coupler to the rear SO-239s
4. Put copper tape on the inside and get it all to connect to ground
5. Test and re-measure levels to get new correction factors for the four bands
6. As far as the software goes, the pwr and swr equations and band selection already works correctly. But I want to spend time on the display presentation and graphics. Fiddling with different fonts and things like a bar graph, placement, etc. takes a long time to get it right. There's just no simple way to do it other than make a change, recompile, and look at what you just did on the actual display.

[metrologist]

You have a Macaw?

[xrunner]

You have a Macaw?

I explained it a few pages back. The neighbor lady behind me has two of 'em. They stayed in the house until the end of this summer, when she decided it'd be a cool deal to buy this gigantic cage. It's on the back porch and the Macaws were being kept in it 24/7. See, they have this really loud screaming noise they make when trying to find their buddies in the rain forest. Oh WTF we don't live in a rain forest but they still do it in the 'hood. So unless I wanted to listen to that crap for the rest of my days (they can outlive their owners) I had to call animal control and have them issue a warning to keep them quiet. So she got them back in the house now.

I mentioned this Macaw issue because, in this topic, we talk about Birds ... 


I'm working on the faceplates. They're not that complicated. The designers of this case chose to do an artistic bevel on each end, so I have to contend with that little issue. Other than that I just need to measure the new dimensions, put in mounting holes in the drawing, then print them in black PLA.

[metrologist]

You have a Macaw?

I mentioned this Macaw issue because, in this topic, we talk about Birds ... 

  Well, I have an Indian Ringneck and Cockatiel.

[A.Z.]

You have a Macaw?

I mentioned this Macaw issue because, in this topic, we talk about Birds ... 

  Well, I have an Indian Ringneck and Cockatiel.

do they measure RF power ?

* A.Z. ducks to shelter

[xrunner]

do they measure RF power ?

* A.Z. ducks to shelter

Radiating Fowl power? 

Here's my first pass on the front panel design. Will print this weekend. 

[p.larner]

ive always regarded them as overpriced as there are lots of other cheaper ways to measure rf power,way overrated if you ask me.