CB and Ham Radio Techs Love Their Bird Wattmeters

[joeqsmith]

Thinking more about local hams getting hold of my meter is freaking me out right now. I went back and added even more reinforcing on the back panel! 

    If it's just for you, I wouldn't worry too much.

When I was a ham I was using RG8U.  I have some RG393 which has similar loss but a lot less flexible.  Same 0.4" diameter.    I think if you were to attach this stuff to a printed plastic case, it would be very easy to crack it. 

https://www.pasternack.com/images/ProductPDF/RG393-U.pdf

That Chinese Nissei meter has some sort of cast metal case with threaded connectors which are in-line.  Guessing the idea was to reduce the bends in the cable and have enough strength to support some RG8U.     

One thing about that meter, note their use of a somewhat air dielectric.  If they make a decent N to mate this rather than my cheap Amazon adapters, it may be interesting to see if these perform better than the standard UHF connectors I have on-hand.  Maybe you could find a source for panel mount ones that would work for your meter.

[xrunner]

  If it's just for you, I wouldn't worry too much.

I'm good at worrying, it's one of my specialties. 

When I was a ham I was using RG8U.  I have some RG393 which has similar loss but a lot less flexible.  Same 0.4" diameter.    I think if you were to attach this stuff to a printed plastic case, it would be very easy to crack it. 

The main issue with large diameter coax isn't so much it will break the rear panel or connectors. It's the fact that it won't allow you to simply place a small light meter on a desk and have it stay in place. Heck even a small mobile transceiver won't easily just sit there right where you want it. I have LMR-400 connected to my VHF/UHF FTM-100D and I had to strap the coax onto the leg of the table and get the bend just right for the radio to sit where I wanted it. I had a Daiwa SWR meter in-line at one time and it was a bear to get the coax to connect in a way that didn't pull the little meter to one side or the other. You have to strap the coax down and when you do that, there isn't really a lot of stress on a little metal box.

Now think of LMR-600 ... that ham I told you about must have C clamps holding it in place wherever he has his radio

[joeqsmith]

Once the cable starts pulling all the equipment off the table, there's some stress.   

[xrunner]

Once the cable starts pulling all the equipment off the table, there's some stress.    /watch?v=JgMVYEoA1Zc[/url]

Oops! Maybe I should ship you my meter for durability tests. 

Rear panel finished. The extra horizontal rib really makes it strong. Not to say a gorilla can't rip the connectors out of there, but the strength ain't bad for plastic. That should conclude all of the 3D printed design I need to do, but if need be I can do more.

[A.Z.]

what about using something like these

https://www.amazon.com/MAGXCENE-Neodymium-Magnets-Countersunk-Storage/dp/B0B48YWRCL

as feet for the box, those should keep it in place as long as it's on a metal surface

[xrunner]

Well ...

They of course would work to hold anything metal (steel) to themselves. However, I have not a single table that has a metal top. I don't think I have ever had a table like that.

Further, they are neodymium magnets. I have some of those and they are very strong, ridiculously strong. That seller even has a picture that shows the unsuspecting person how to properly separate the magnets from each other. They would hold heavy items up on a wall as in that picture (I'll get to that pic they show in a second). But I suspect letting the magnets attract large objects like solid steel tools would ruin them in short order due to the metal banging against the magnet when the tool gets within a very short distance - you won't be able to stop that. Some people who bought them even uploaded pics of the damaged magnets because they are strong but delicate.

 

If they were used as feet, say four feet, on a small project box the box would most likely stay put on a steel table top. But good luck in picking the box up off the table. You won't be doing that. You'll have to slide it off the table if you have to remove it.

*****

Now the picture ... that picture they show (attached) is totally bogus. It's a photoshopped image. Look at the size of the key compared to a hammer or shovel - it's gigantic.

 

Oh and the shovel - it won't be hanging from a magnet like that. Well unless the magnet is some kind of advanced material discovered from alien UFO technology in area 51 that attracts plastic. I have tools like that and they all come with plastic handles nowadays. But put the shovel blade on the magnet - yea that would work - but it will start cracking the magnet every time it gets close because it will slam hard into it (see above comments).

 

[A.Z.]

well, you don't need to buy them, if you have a bunch of old HDDs around just open them, you'll obtain a bunch of neodymium magnets, but then they'll be in some unsuitable shape; as for those items, they were an example in case you decided to seem stupid; anyhow, the "metal" surface "issue" and the "detach" one are easily solved with a microgram of gray matter, I did and I've none; so you will probably do better, then regarding the pics, I "suppose" you know about that stuff but then, and again, it's probably all due to my lack of gray matter, will need to seek amazon and see who sells it

[joeqsmith]

Before attempting to improve that Chinese Nissei meter, I thought I would find some other crap CB/hamster meters to compare with it.  I only have that old Mars VSWR meter which doesn't display Watts. 

This was the first junker.  I do mean junker.  Looking at the coupler's performance, like the Nissei, I don't see how this would ever do much of anything.  After seeing this, no wonder the CB/hamster's looked to the Bird as the gold standard. 

[xrunner]

This was the first junker.  I do mean junker.  Looking at the coupler's performance, like the Nissei, I don't see how this would ever do much of anything.  After seeing this, no wonder the CB/hamster's looked to the Bird as the gold standard.

Yea, remember I was going to convert that Daiwa SWR/PWR meter to a digital readout just for fun. But when I started looking at the construction of the coupler, I decided not to waste my time on a piece of junk.

Well, some people will still say I'm wasting time but at least it's something that has some quality associated with it. 

What I need to do now, since I have all the case parts designed and printed, is to add the copper tape shielding before I forget about it. Eh, it's not the funnest thing to do but is has to be done. 

[joeqsmith]

I could ditch everything but the case and meters.  Put a new coupler and PIC in there with a few of the LOG amps.  Then drive the meters from the PIC.    

[xrunner]

I could ditch everything but the case and meters.  Put a new coupler and PIC in there with a few of the LOG amps.  Then drive the meters from the PIC.   

That is a really great way to make use of those parts and I'm looking forward to your progress on that idea. 

One of my goals here is to keep this thread you started in the top three on this board in terms of views. Between you and I we have the top three threads on this board in terms of views -

joeqsmith: NanoVNA Custom Software 423440 Views

xrunner: Whatever Happened to Ham Radio? 245399 Views
    
joeqsmith: CB and Ham Radio Techs Love Their Bird Wattmeters 143798 Views

Hey nobody can say were not good at anything. 

[joeqsmith]

Manual I found didn't have a schematic so I traced out the hamster wheel.  It's crude.  Makes the cheap Radio Shack  meter look high tech.   Guessing this thing was targeted for the CBer with a large linear, as they talk about it being factory calibrated at 27MHz.  They make no claims about accuracy, or even the range it could be used.   I did find an ad where they claim 220MHz.   Maybe they consider if the meters have any response, good enough.     

Still, seems symmetrical and guessing that the VSWR and modulation may have worked alright for what it is.  Power for the 160-6M bands, no way.   

[xrunner]

Before the copper tape is applied I decided to glue the risers to the bottom half of the case. That will make it a lot easier and they really don't need to come off again from there.

The glue I used is SciGrip 16, which will glue PLA and styrene together. If you're a glue-sniffing addict, this stuff would be your dream drug of choice.

*** BONUS PIC ***

I read some reviews and decided to buy a Pinecil mini soldering iron. It isn't for large jobs but I really like it so far. It comes with a conical tip which I don't prefer so I ordered a few more tips to try. I'm powering it from an old 20V laptop supply brick and had to put on a temporary power plug since I didn't have any 5.5 x 2.5 spare solder plugs (on order). It can also be powered from USB C power delivery.

It has a 144 MHz 32-bit RV32IMAFC RISC-V SiFive E24 Core CPU which runs firmware called IronOS. When I was a kid I'd never have thought one day my soldering iron would have a processor inside it to make it work.

[joeqsmith]

I read some reviews and decided to buy a Pinecil mini soldering iron. ....

It has a 144 MHz 32-bit RV32IMAFC RISC-V SiFive E24 Core CPU which runs firmware called IronOS. When I was a kid I'd never have thought one day my soldering iron would have a processor inside it to make it work.

I remember an article, maybe EDN, from the early 80's about a king and his toaster.  We all laughed at the nonsence of putting a micro into a toaster.   Google finds a similar story...

https://www.ecb.torontomu.ca/~elf/hack/ktoast.html

Still, I just repaired the in laws toaster, which certainly has a micro.  This is what my family believes I do for a living, repair toasters.... 

[joeqsmith]

When I was looking at the old time meter, the coupling really falls off as you move down in frequency.   At a MHz, I think it was 60dB or more.   

I had made some test loads for when I was working on my home made Watt meter.  These are only rated for a couple of Watts.   I started out a 27MHz where the meter is supposed to work and it wasn't sensitive enough to read the reflected signal, even with a VSWR of 4:1.  I think the idea was, what self respecting CBer would only use a few Watts.  This meter supports a kW afterall.  It's not made for the kiddies.    

They had used all 1N4148s for the detectors.   I picked up some 1N5711s to try and improve the sensitivity.  These one on one tape and they appear all very close.  These were not the 100 for a dollar ones on Amazon.  It did improve it somewhat.  So I tried it with a VSWR of 3, 2 and 1.5 all at 27MHz.   3:1, I would expect would be much closer.  There is no adjustment and I suspect would be good enough.     

[joeqsmith]

I left the 75 ohm resistor attached (1.5 VSWR) and tied it at 14, 7 and 3MHz.   The signal is just too small, even with the new detector diodes to get a good reading.  I tried to increase the power to the point where the resistor was getting a bit too hot for comfort, but no luck getting a decent reading.   It's certainly not a meter for the HF hamsters. 

A working Bird meter would put it to shame. 

[joeqsmith]

The coupler uses four brass rods to couple to the transmission line (if you want to call it that).  They have two rods for forward and reflect for the VSWR measurement. One to measure  modulation and one to measure power.   Each circuit is isolated.  It is treated like three unique meters with a common transmission line.  Maybe three different designers.  I'm sure there is a story.    

Using the LiteVNA to look at the impedance with the antenna connection open.  The first dip to 25 ohms is that old UHF connector the ham and CBers like so much.  Then we have the sort of transmission line followed by the last open circuited UHF connector.

[vk6zgo]

When I was looking at the old time meter, the coupling really falls off as you move down in frequency.   At a MHz, I think it was 60dB or more.   

I had made some test loads for when I was working on my home made Watt meter.  These are only rated for a couple of Watts.   I started out a 27MHz where the meter is supposed to work and it wasn't sensitive enough to read the reflected signal, even with a VSWR of 4:1.  I think the idea was, what self respecting CBer would only use a few Watts.  This meter supports a kW afterall.  It's not made for the kiddies.    

They had used all 1N4148s for the detectors.   I picked up some 1N5711s to try and improve the sensitivity.  These one on one tape and they appear all very close.  These were not the 100 for a dollar ones on Amazon.  It did improve it somewhat.  So I tried it with a VSWR of 3, 2 and 1.5 all at 27MHz.   3:1, I would expect would be much closer.  There is no adjustment and I suspect would be good enough.   

Many years ago, I picked up a CB style SWR meter at an establishment calling itself  "Crazy Charlies".
This was in the "returns" tray & was clearly marked faulty.
I thought "might be some useful bits" & picked it up for $A4.00.

I took it home, stuck it on the old 2m "modified taxi radio", & was gratified to see some meter movement.
I took it to work, stuck 8 watts into it from the same radio in line with a Marconi power meter/load & checked the VSWR displayed on the CB meter.
It said, as expected, something around 1.3:1, which was reasonable for something sold as "not working".

Work having an assortment of loads I managed to find a 75 ohm one. The SWR read around 1.6:1- near enough!

It wasn't a "power meter's bootlace" as the "forward power" reading was adjustable to give full scale.
Who cared, as I could borrow the old "Macaroni" one?

From memory, it used OA91 or 1N34 style diodes.

When it came to tuning up 2m antennas, the alternative was to borrow a Grid Dip Meter from work, so it was reasonably useable to "Get in the paddock of where I wanted to be".

Strangely, this particular design of VSWR meter increased in sensitivity at HF, so when I finally got on HF, it was still useful.
Obviously, nothing you would use for work, but ham radio IS just a hobby!

Over time, I have "picked up " several more pretentious CB & even ham SWR meters cheaply, but almost universally the more pretentious, the less likely they were to work.
Finally, the meter failed in the "Crazy Charlies" one & it went in the bits 'n pieces box, but by that time, I had a R-x Noise bridge which was "sorta" useful, & sometimes , access to an MFJ 259.

By dint of not being very active, I went along till I bought a nanoVNA.

Having "short arms & long pockets", I never aspired to possess a Bird.

[xrunner]

Still, I just repaired the in laws toaster, which certainly has a micro.  This is what my family believes I do for a living, repair toasters.... 

Yes yes ... you have the "knack". Maybe they don't really realize you became an engineer. Don't tell them at this point in your life, it would be devastating to them.

[vk6zgo]

Don't tell my Mother I'm a Technician---she thinks I play the piano in a brothel!

[xrunner]

Don't tell my Mother I'm a Technician---she thinks I play the piano in a brothel!

Oh yes, piano player in a brothel is a respectable job - much more respectable than the electronics profession. Let her keep thinking that. 

[vk4ffab]

Bird Watts. Is that an SI unit? Or an a this Unit is a Silly Idiot?

[metrologist]

They had used all 1N4148s for the detectors.   I picked up some 1N5711s to try and improve the sensitivity.  These one on one tape and they appear all very close.  These were not the 100 for a dollar ones on Amazon.  It did improve it somewhat.  So I tried it with a VSWR of 3, 2 and 1.5 all at 27MHz.   3:1, I would expect would be much closer.  There is no adjustment and I suspect would be good enough.   

That actually seems pretty good for what it is supposed to be. Not everyone starts riding on a VMAX. 

[joeqsmith]

Looking at the modulation feature of the low end hamster wheel,  if I align the meter at 27MHz and 99% modulation, it is a way off at 20%.  Aligning it at 80% modulation gets things in the ballpark, sort of. 

[joeqsmith]

If I increase the frequency to 140MHz and use 30% modulation, the meter reads nothing.  SWR on the other hand works reasonable as I would have guessed.