CB and Ham Radio Techs Love Their Bird Wattmeters

[xrunner]

Here are some photos of what they look like inside.  Looks like a lot of labor.
http://www.repeater-builder.com/projects/bird-element-tour/bird-element-tour.html

Yup. The accuracy of the thing depends not only on the electronic components inside, but also the spacing of the mechanical parts. If that spacing is not correct, you ain't going to get the right answer on that meter.

[Wallace Gasiewicz]

Without a calibrated reference, I'm at the mercy of what ever my out of cal vintage equipment does.   If I connect the RF generator directly to the spectrum analyzer and sweep from 1MHz to 100MHz and -120dBm to 10dBm we get something like the attached.   If the two instruments and cable were perfect it should be obvious that we would see a perfect line at -120,-120  to 10.10.     The hams and CBers would need to chime in how their Birds would fit into this...    Oh right, the gold standards....

As you can see, things start to fall apart around 90dBm.   The crappy cables and adapters had to be removed to get this good.   No taped up red coax with wrong connectors on them..

Don't be silly. Any decent CBer would figure out a way to get that -100 dBm signal up to at least 5 KW and there it would be easier to measure

[xrunner]

Here ya go!

http://www.cqdx.ru/ham/new-equipment/digital-meter-kit-for-the-bird-43-wattmeter/

[joeqsmith]

As I understand it, the ham while climbing the mountain to check their remote site, does not want to get there only to discover dead batteries.  The mountain top ham shack does not have lights and they need more than a 90 second backlight timer.   The mechanical movement is bullet proof (except the ones now made in China).  They survive the worse conditions known to man for many decades.   There's no way that delicate electronic head will be as robust.   And what about all that sun light at the top of the mountain?  Is it sun light readable?   While the hams love to mod their Birds to add peak detect circuits and play for hours adjusting the pots to get the movement to work just the way they want,  this kit missed out.   Really, what you want is an electronic measurement circuit that drives a stepper motor meter, like what's in your vehicle.   

Of course the biggest problem is for the CBer.  Saying your 100W amp is able to put out 102W and then based on this meter would get you in a bar fight.      

[xrunner]

Hmm ...

Well, how about a gold-plated Bird for that special gift?

https://www.electronicdesign.com/home/article/21200599/watts-my-true-rf-power

[CJay]

Hmm ...

Well, how about a gold-plated Bird for that special gift?

https://www.electronicdesign.com/home/article/21200599/watts-my-true-rf-power

That's even more gold standard accurate because it's goldier!!!

[bd139]

That was a great read with my morning coffee. I’m sure he takes his Bird to bed every night 

[vk6zgo]

As I understand it, the ham while climbing the mountain to check their remote site, does not want to get there only to discover dead batteries.  The mountain top ham shack does not have lights and they need more than a 90 second backlight timer.   The mechanical movement is bullet proof (except the ones now made in China).  They survive the worse conditions known to man for many decades.   There's no way that delicate electronic head will be as robust.   And what about all that sun light at the top of the mountain?  Is it sun light readable?   While the hams love to mod their Birds to add peak detect circuits and play for hours adjusting the pots to get the movement to work just the way they want,  this kit missed out.   Really, what you want is an electronic measurement circuit that drives a stepper motor meter, like what's in your vehicle.   

Of course the biggest problem is for the CBer.  Saying your 100W amp is able to put out 102W and then based on this meter would get you in a bar fight.   

Not many hams have remote sites, but commercial two way radio & pager services did, & may still do.

A Bird sitting inline between the TX output & the transmission line is a very useful indication of correct operation.

Marking the meter scale at the reading coinciding with the correct output power, as determined by better equipment during installation was a trick often used commercially.
That way, it doesn't much matter if the Bird is reading a bit high or low, it is still a good indicator of correct power level.

The hams who look after repeaters, beacons , & the like, are most often employed in the RF field, & have loan access to much more sophisticated equipment than Birds to set the place up to "spec".

By the way, "remote sites" are normally buildings of some kind,--in the ham case, usually reasonably well constructed metal sheds.
LED lighting is cheap & economical, as you need a solar panel & batteries to run the equipment, in any case.
Of course, if the electricity company has run power up the mountain, "all bets are off"!

In the quite different case of a ham sitting open to the elements on a "bare" (blunt) mountain peak, chasing "peaks on the air" contacts, I very much doubt that anyone would take a Bird, original, or modified with them, as they are additional weight, but they may take an El Cheapo SWR meter, or a Nano VNA to check the antenna.
Some others, may simply rely upon the inbuilt VSWR/power meter in the transciever.

[cgroen]

I suspect this is far too complex for the ham group.   There's software that would need to be installed and manuals that would need to be read.   The mechanical Watt meter is much better suited.  Even if the owner has no clue about accuracy, percent of full scale, load mismatches.....  They should be able to see the needle bounce. 

https://birdrf.com/Products/Sensors/RF-Power-Sensors/RF-Power-Sensors/5017D-Wideband-Power-Sensor.aspx

Being a little general here... ?

[Wallace Gasiewicz]

Instruments like the Bird are very useful. Even the really cheap old VSWR meters are just fine. (like the ones from Sears)
People who use radios as part of making a living (some truck drivers) need simple reliable instruments to help them. These people are not radio tecks and do not want to be.
Frequently this is an old cheap VSWR meter to make sure that the antenna system is working OK and not going to blow your finals. It is tough to put an antenna system on a new truck with fibreglass body and have it work.
These things do not require batteries or complicated calibration and are as close to foolproof as we can get.
They are accurate enough for their intended task.
Then someone gets fancy and gets a Bird and gets;   

[joeqsmith]

I suspect this is far too complex for the ham group.   There's software that would need to be installed and manuals that would need to be read.   The mechanical Watt meter is much better suited.  Even if the owner has no clue about accuracy, percent of full scale, load mismatches.....  They should be able to see the needle bounce. 

https://birdrf.com/Products/Sensors/RF-Power-Sensors/RF-Power-Sensors/5017D-Wideband-Power-Sensor.aspx

Being a little general here... ?

The whole thread is generalized.   

[A.Z.]

Even if the owner has no clue about accuracy, percent of full scale, load mismatches.....  They should be able to see the needle bounce. 

... with the slug inserted in "ref power" position and while pumping several "birds" of power into a screwdriver antenna and, at the same time, without any shack grounding at RF :-D

[joeqsmith]

Marking the meter scale at the reading coinciding with the correct output power, as determined by better equipment during installation was a trick often used commercially.
That way, it doesn't much matter if the Bird is reading a bit high or low, it is still a good indicator of correct power level.

The ham & CB hobbyist know everything else is the source of the error.   Birds ALWAYS display the correct power.  Even the ones that have been "repaired" by sharply banging them on a hard surface.   

Well, how about a gold-plated Bird for that special gift?

I wonder if they offered it in the Neiman Marcus Christmas Catalog.   

[xrunner]

Would a yellow Bird Model 43 appeal to anyone? Well it did for at least one person. Repainted? Can't google any other examples of this color Bird 43 - might be very rare!

Easily seen in the taller grass, or if stolen, might stand out at the hamfest flea market. 

Starting bid $149 located in Mexico. Hurry!

eBay auction: #175325126533

[bd139]

Looks like a steam punk minion.

[vk6zgo]

Would a yellow Bird Model 43 appeal to anyone? Well it did for at least one person. Repainted? Can't google any other examples of this color Bird 43 - might be very rare!

Easily seen in the taller grass, or if stolen, might stand out at the hamfest flea market. 

Starting bid $149 located in Mexico. Hurry!

eBay auction: #175325126533

I think it is a production item, as I seem to remember seeing one in service somewhere.
Maybe an option for customers who feel a standard "battleship grey" one is too easy for evil-doers to steal & sell off to buy drugs.

[bd139]

Probably a US Navy spec item like those big floating yellow HP scopes.

[xrunner]

After taking more data and thinking about what I want to do with this project, I've decided on an HF and higher amateur radio band power meter. This is something I think a few of my ham friends could use; I'll make them and ask for just my cost back. They (having come to my house and seen more expensive hp meters) will understand that an external attenuator must be attached (to test their transmitters) and they understand what will happen if they make a mistake and don't use it.

I also want to do one for the calibrated full coverage up to ~500 MHz, but this right now seems like more fun.

HF (1 to 30 MHz) Corr. factor -0.83
6 m (50 to 54 MHz) Corr. factor -0.25
2 m (144 to 148 MHz) Corr. factor +1.3
1.25 m (222 to 225 MHz) Corr. factor +2.9
70 cm (420 to 450 MHz) Corr. factor +8.0

As you can see in the spreadsheet, for each of the bands, I can use just one cal factor per band and easily get better than 0.5 dB accuracy. The cal factors will be selected via a front panel button. The display will show which band is selected and behind the scenes the cal factor will be selected. There will also be a second button to tell the system what value of external attenuator you are using (0 to 50 dB) in 10 dB steps indicated on the OLED display. Both of these inputs will then give the corrected power on the display. The display will show both dBm and Watts at the same time.

Since the defined safe upper limit I'm using will be +13 dBm (it could be a little higher but for safety ...) and a 100 W transmitter is +50 dBm, they will require at least a 40 dB att. to get back down to +10 dBm, preferably a 50 dB att. One guy already has a 40 dB attenuator.

This is really no different than how a meter such as the hp 437B does power measurement. It also has a table of cal factors you enter per sensor, which when you enter a frequency, corrects the measurement. It also has means to input any external att. value so the readout is corrected.

This meter also has the advantage, unlike meters like the Bird 43 or Coaxial Dynamics type meters, that it can measure a whole lot lower power levels accurately if you want to use it for other types of power measurements. The accuracy of this meter is not x% of full scale either, much better than that.

For the case, I will do the same thing I did for my GPS NMEA decoder project, which is to house it in an aluminum case. But I will design the custom front and back to be 3D printed because that makes it a whole lot easier to fit the components that need to pass through the front and back plates. The boards inside will fit onto a slide-in bottom mounting plate.

Now that I've said it, I have to actually do it. 

[joeqsmith]

I wonder if you put on your marketing hat and took the time to ask your ham friends what they want,  what their response would be.  Be customer led. 

What do they currently use?
Analog/Digital readout?
Bands?
Power level?
In-line?
VSWR?
Vector?
Modulation?   Some of them have audio output.   
Data logging?
Safety shutdown?
Most important, you want to make sure you ask about the color making sure they understand gold plating and yellow are options.   

[xrunner]

I wonder if you put on your marketing hat and took the time to ask your ham friends what they want,  what their response would be.  Be customer led. 

I thought you've been around hams Joe, don't you know -

What do they want ? everything

How much do they want to pay for it? nothing

 

I'm just going to make a couple for two guys and charge what the parts cost. I already texted one and showed the prototype and what I'm going to do, he said oh yea I'd like one. He actually does know how to set the transmitter power output on radios to the spec in the manual so this would be an improvement over his current power meter. The other will probably want one too, but if not meh.  I can always use another power meter. 

Most important, you want to make sure you ask about the color making sure they understand gold plating and yellow are options.

Yes the color! Well the main housing will be aluminum, but the front and back plate colors could be an option, I will ask of course.

I wonder if you put on your marketing hat and took the time to ask your ham friends what they want,  what their response would be.  Be customer led.

Back to ya - who are your customers? 

[joeqsmith]

I thought you've been around hams Joe, don't you know -

What do they want ? everything

How much do they want to pay for it? nothing

 

Based on my own experience when dealing with them:
Not only do they want it for free, they are entitled to free service and training as well.

When do they want it? now 
 

I wonder if you put on your marketing hat and took the time to ask your ham friends what they want,  what their response would be.  Be customer led.

Back to ya - who are your customers? 

Outside of myself, none.  Like the majority of my home experiments,  it becomes an academic exorcise driven purely by my interest in electronics.  The requirements are wide open.   

[xrunner]

Outside of myself, none.  Like the majority of my home experiments,  it becomes an academic exorcise driven purely by my interest in electronics.  The requirements are wide open.

I can agree with that. 

[bd139]

The moment you add customers to a problem it becomes a chore

[xrunner]

Just adding notes along the way. I need at least two control buttons for this power meter project. One to select the ext. attenuation, the other to select the band for the correction factor.

For any anyone reading who is learning microcontroller projects: If you're going to use buttons for control you'll run into noise issues with them, a common problem. You need to "de-bounce" the buttons for reliable control. You can see a button I'm testing in the screen shots below, before and after adding hardware debouncing.

Even though there are software solutions to debouncing using timing (which I've used), the circuit below works just fine for anything I've done in the past with buttons. Then you don't need to add more code. See the article linked.

https://hackaday.com/2015/12/09/embed-with-elliot-debounce-your-noisy-buttons-part-i/

Why am I testing button debouncing now? Because I don't want mysteries to have to debug later on. One thing at a time, one module at a time, that's how I roll. The more you test up front, the less mysteries you will have along the way. Trust me.

[bd139]

Most of the code in my implementation was debouncing one button 

Decided to do it with pin change interrupts and timers 

It handled short press, long press and was entirely non blocking. Probably should have just used FreeRTOS or something by that stage of development