CB and Ham Radio Techs Love Their Bird Wattmeters

[xrunner]

I was thinking Xrunner was trying to be a leader rather than a follower.   First, building anything is a huge step ahead.   Then attempting to piece together a VSWR Watt meter with software... another notch up.  Then not bowing to Bird is the gold standard makes him even further up the food chain.   Then flushes all those bonus points down the toilet by using a 1930's unstable connector....     

 
 
But I'm sparing no expense - I have silver plated SO-239s!

[joeqsmith]

Note the photo of my BNC barrels.  One of them is not like the others.  Guess which one is silver. 

https://www.eevblog.com/forum/rf-microwave/experimenting-with-waveguides-using-the-litevna/msg5072725/#msg5072725

I wonder about some of these super low cost Chinese connectors.  Some are < $10.  They have some "precision" ones around $50 but none have any data.

[joeqsmith]

Let's see what the hammer damners say.

This one claims there is no measurable difference:
https://www.iz2uuf.net/wp/index.php/2016/01/08/pl-259-vs-n-on-430-mhz/

This one thinks it's a Apple vs PC, Red vs Blue, Ford vs Chevy thing.   "An argument that really has no answer, but people think they know the answer, and what answer they have is held firmly and vigorously."    This is going to be good....

****
He claims in Europe everything is N.  USA used the old UHF connector.   Makes sense.  We can't even sort out the metric system here.   After watching,  I'm thinking to swap out the N's on all of my test equipment for the old 1930's UHF connectors so I can be more American!  USA USA   

Measure your silver ones and lets see what you get.   

[xrunner]

This one thinks it's a Apple vs PC, Red vs Blue, Ford vs Chevy thing.   "An argument that really has no answer, but people think they know the answer, and what answer they have is held firmly and vigorously."    This is going to be good....

He talked a lot, showed some drawings, but didn't show any data to back up his opinions. I figured that was going to be the case before I even watched it.  An argument that has no answer he says? Red vs Blue, Ford vs Chevy? PC vs Mac? Ridiculous! 

I found some graphs that show some very good data (S21 & others). The site is here -

https://www.hamradio.me/connectors/uhf-connector-test-results.html
 
The insertion loss plot shows that the N connector is clearly better than the PL-259 (UHF) connector (SMA and TNC are even better), particularly at the 220 MHz ham band and above. N connector probably gets to a max insertion loss of 0.3 dB @ 580 MHz and doesn't get any worse all the way to 1 GHz.
 
The best UHF connector overall (they show several different types, see explanation in link) is almost 1 dB worse than the N at the worst spot (850 MHz) (even though another UHF type that is worse overall is better than the other one at that particular spot). The more inferior types of UHF connectors just get worse than that. See link for more detail and other types of plots.
 
 So no, video HAM dude, there is an answer, you just didn't look for the data. Your video was dated two years ago - 2021. The linked article I found was dated Dec 2016. You are LAZY.
 
 

[vk6zgo]

Note the photo of my BNC barrels.  One of them is not like the others.  Guess which one is silver. 

https://www.eevblog.com/forum/rf-microwave/experimenting-with-waveguides-using-the-litevna/msg5072725/#msg5072725

I wonder about some of these super low cost Chinese connectors.  Some are < $10.  They have some "precision" ones around $50 but none have any data.

The least shiny one is the silver one.

There is also the fact that there is silver and silver!

Many years ago, EEs at the (then) PMG's Dept Research Lab did some tests on large self-supporting coils made out of copper pipe, which were part of a LC tuned anode circuit of a tube PA at HF frequencies, as they had been reported as becoming hot in service.

The coils were silver plated, using a standard commercial plating service & were very pretty.
As a control, the "ginger beers" made up a set of coils from unplated copper.

Under test, they were surprised to find that the plain copper ones ran considerably cooler.
As this was counter intuitive, they then had to go down that "rabbit hole"!

It turned out to be due to two interacting things:-

(1) Copper available in the late 1950s contained many fewer impurities compared to that from the early part of the century when silver plating definitely did improve efficiency in "tank" circuits.

(2) Silver plating methods had changed since those early days, as platers introduced various compounds which increased the brilliance, wear & tarnish resistance of plating for their primary purpose of making things look "pretty".
Unfortunately, this caused a very large increase in the resistivity of the plating.

They concluded that the "laid back" attitude of "just dropping your stuff into the local plating shop" obviously needed a serious rethink!

[joeqsmith]

A few other articles from I believe the same author, along with his resume:

https://www.hamradio.me/connectors/pretty-lousy-pl-259-connectors-the-test.html
https://www.hamradio.me/connectors/pl259-so239-return-loss-attenuation-test.html
http://www.johnhuggins.com/resume/resume.php

Attached showing an antique detector.  Guess which connector has the lower frequency and which was for the higher...

[xrunner]

Here's the side risers with correct dimensions. Fit well so on to the next step.

[vk6zgo]

The side risers are a great idea.

I was really put off those "standard project boxes" as any worthwhile project I wanted to make was always that little bit too tall to fit.
I usually ended up either finding a scabby old box which never looked like anything, paying too much for a box that was too large, or just "having a lie down till the feeling went away".

Even the steel boxes were like that---I remember ending up making a linear power supply for some tube equipment where the transformer laminations protruded through the top, like a supercharger on a hot road car.

Nobody could get bitten, as the hole was very snug, but it just looked wrong!

[xrunner]

The side risers are a great idea.

Thanks.

I was really put off those "standard project boxes" as any worthwhile project I wanted to make was always that little bit too tall to fit.
I usually ended up either finding a scabby old box which never looked like anything, paying too much for a box that was too large, or just "having a lie down till the feeling went away".

The only parts of the plastic box I bought that I'm using are the top and bottom. It's certainly possible to 3D print a whole box and not buy one. I might do that in the future. It just takes a lot longer to make a large part like the top or bottom of the box I'm using. But once you get all the parts designed or found on Thingiverse, you can make any size box very easily. All you have to re-size all the parts in the slicer, like 50% or 200% or whatever. All the parts will fit together.

What I really would like is a PLA that has enough metal in it to act as a shield. They do make "metal" PLA but the metal particles are just there to obtain a nice looking print, not to conduct. I guess there would have to be a lot more metal particles, so much so that we'd be talking about actual molten metal at that point.

 

[joeqsmith]

We tried to print high content copper PLA then sintered.  I showed the results in the waveguide thread.  Very conductive, basically a chunk of copper.  However, instead of a nice looking waveguide, it looks like a blob of burnt copper.   

[vk6zgo]

The side risers are a great idea.

Thanks.

I was really put off those "standard project boxes" as any worthwhile project I wanted to make was always that little bit too tall to fit.
I usually ended up either finding a scabby old box which never looked like anything, paying too much for a box that was too large, or just "having a lie down till the feeling went away".

The only parts of the plastic box I bought that I'm using are the top and bottom. It's certainly possible to 3D print a whole box and not buy one. I might do that in the future. It just takes a lot longer to make a large part like the top or bottom of the box I'm using. But once you get all the parts designed or found on Thingiverse, you can make any size box very easily. All you have to re-size all the parts in the slicer, like 50% or 200% or whatever. All the parts will fit together.

What I really would like is a PLA that has enough metal in it to act as a shield. They do make "metal" PLA but the metal particles are just there to obtain a nice looking print, not to conduct. I guess there would have to be a lot more metal particles, so much so that we'd be talking about actual molten metal at that point.

 

It is possible to electroplate plastics, & it was done quite a lot for decorative purposes, back in the day.
They deposited a layer of graphite & plated over that.
Even recently, my daughter's Hyundai car had chrome plated plastic inside door handles.

In most cases, with chrome, durability was a problem, as it was with the Hyundai----the chrome peeled off anywhere there was a "sharpish" edge, so the next model had plain plastic handles.

Copper, & a less complex shape may be more forgiving.
Of course, that's another rabbit hole to go down, maybe to no avail.

[joeqsmith]

Of course, there is that MGC paint I used on the waveguides.  In the end, I could not tell the difference between a coated printed horn and a metal one.   Member Coppercone2 had a different experience than I did with it, so keep that in mind.   

[xrunner]

Started to try my hand at making up some semi-rigid with SMAs. I had a small tubing cutter I used for modelling that seemed about right for cutting the coax. It worked really well. So far so good ...

[joeqsmith]

You will need to test these after you make some up.  While I would check them with a depth gauge, I understand this is unpopular with hams, much like torque wrenches.  So here is W8JI to the rescue to show you how to properly test them.   

[xrunner]

Well ... I don't have the measurement rig that you have. However, I did obtain the SMA male dimensions shown in the attached files (https://www.rfconnector.com/rf-connector-dimensions)

I can measure the depth "E", which can be Min=2.54, Max=3.43 (mm)

The center pin can protrude according to dimension "H", Min=1.91, Max=2.54 (mm)

Note: The center pins that came with my SMA males have a sharp point not a blunt point like the picture.

Thus, "E" can be a minimum of 2.54 mm, and "H" can be a Max of 2.54 mm. Therefore, to wit, the end of the pin can align exactly with the edge of the SMA Male and it would satisfy the dimension tolerances.

 

[metrologist]

Analog Dial indicators. I love them. I have dozens in all manner with a myriad of mounts. A great late 1800's technology that I've been using for decades. Get you some!

[A.Z.]

Let's see what the hammer damners say.

This one claims there is no measurable difference:
https://www.iz2uuf.net/wp/index.php/2016/01/08/pl-259-vs-n-on-430-mhz/

Read the SECOND part, don't stop at the front door

https://www.iz2uuf.net/wp/index.php/2016/01/15/pl-259-vs-n-round-2-hard-testing/

[joeqsmith]

I had seen their part II but stopped at the TDR.   Guessing their VNA wasn't up to the task to resolve the 25 ohm like myself and others have shown.  Then again, when it comes to TDR, that is one topic I hear a lot from hams about.  The best was how you could reduce the number of samples to a very small number to achieve higher resolution.  Sad thing is there are countless papers available for free on the internet written by the major players.  Just requires reading. 

[A.Z.]

let aside the "ham" stuff, Davide worked for several years for

https://www.viavisolutions.com/en-us/products/railway-and-mcx-assurance

that said, how much will that "discrepancy" affect you project ?

[joeqsmith]

Keysight employs janitors and people taking care of the plants.   I would be more curious what they actually did as a profession.  Even then, humans like to embellish. Pick any discipline and there are bad, medium and good people.   Better to base my comments on their published works.

My current project is sub 25kHz using screw terminals and phono jacks.

[A.Z.]

well you may ask him if you want

https://www.linkedin.com/in/davide-achilli-0281593

[joeqsmith]

I've never had a linkedin account or any desire to network.  No twitter, facebook, or the countless others.    Outside of my tiny presence on YT and EEVBlog, that's about it.   

***
Appears he made all of his YT content private.  Guessing because of the backlash.  Otherwise I could have posted a message there.   If you know him, you could always invite him to join us.   

[joeqsmith]

Of course, I have recently posted some data for these old UHF connectors:

https://www.eevblog.com/forum/rf-microwave/cb-and-ham-radio-techs-love-their-bird-wattmeters/msg5081245/#msg5081245

Lets have a little more fun with them.  Here is my ham station / Watt meter simulation.  It has a couple of feet of coax, six UHF adapters and 4 BNC adapters.  We can start by looking at the TDR with a VNA that has very limited BW, say 1.5M to 500M.   We will terminate the far side of the setup to 50ohms.   Looks like the VNA measures 50ohms spot on.   All those UHF connectors look as good as having the terminator attached directly to the VNA.   Right?

***
New day, fresh eyes.  Why was the data so good??  Notice the VNA was set to TDT rather than TDR.     Same setup with the proper settings.  Green trace is with the terminator directly connected to the VNAs test cable.   White is with our string of UHF connectors/adapters and coax.   Now we get results very similar to your friend's IZ2UUF.    All is right with the world again. 

[joeqsmith]

I am using the $120 LiteVNA for this demo, with the supplied cables and standards (except for my sorted terminator).  I am also using the ideal model. 

The Lite isn't limited to 500MHz.   You can get some useful data out to maybe 8GHz.  For TDR, frequency range gives us the resolution.   Even 8GHz isn't going to provide very good resolution but we can paint a bit clearer picture of what our UHF connectors look like.

[joeqsmith]

I know, hams are all about SWR and from what I have been told from one ham, 3-places beyond the decimal point is important.  Let's have a look at the SWR vs frequency in the range of 10MHz to 500MHz with a decent load attached to our UHF adapter setup (yellow).     Next let's connect the load directly to the VNAs cable (red).