CB and Ham Radio Techs Love Their Bird Wattmeters

[joeqsmith]

Come on Joe, you know better than that!

You can sleep better tonight!    

[vk6zgo]

Ham's using their Bird to measure some coax. 

I did sit through that, & it wasn't that bad.

I thought "Uh, oh!" at the beginning, where he mentioned in passing about cutting your coax to a half wavelength, but his further remarks clarified his meaning.
Many hams are either too old & doddery, or too unfit to hang off a mast or ladder in the sky & measure at an antenna feedpoint, so it is a useful trick to use the characteristics of a half wavelength to repeat the antenna impedance inside the ham shack.

The rest was quite reasonable, showing that it doesn't need super accuracy to determine the loss of a length of coaxial cable to within a dB of the spec.
His major point, though, was the much greater losses at VHF & above, which may not be intuitive to those who don't mess with this stuff for a living, or for fun.

[vk6zgo]

Come on Joe, you know better than that!

You can sleep better tonight!   

Why---knowing you were just trolling?

[joeqsmith]

Even with the the last changes with the fitters, it looks like it can sample over 6kHz. 

I watched a ham video where they modified the decay for their Birds peak peak detector by changing a cap.   While they didn't show the actual cap, they did a find job showing the effects.    In our case, its just software so I added a trim for the decay.   

[joeqsmith]

Come on Joe, you know better than that!

You can sleep better tonight!   

Why---knowing you were just trolling?

Because you're starting to figure the point of the thread out.  Better late than never...   

[vk6zgo]

But you know all this crap & are just playing dumb for some unknown reason!

Why would you waste so much time blabbing on and on then?  Oh right!   

Because, unlike you, some people don't know, & take your remarks at face value.
The way I see it, we can all go away & leave you & xrunner to your own private thread, seeing you are having "a whale of a time", or comment  if we want to.
In either case, it is up to us, & I'm sorry if I dont genuflect.

[mansaxel]

His major point, though, was the much greater losses at VHF & above, which may not be intuitive to those who don't mess with this stuff for a living, or for fun.

You mean, it's intuitive for people who read spec sheets for things. (and get at least a so-so comprehension of their contents and their implication)

I am an imperfect person, and I have a callsign, a relatively modern Swedish license. But I read the specs. And I have since I was like 15, when I did not understand them much. Still don't, but I've grasped the concept of angry pixies running back and forth faster needing a better path...

[bd139]

Did you say a while back you ordered another log amp to play with? Seems like you said you did.

Yes I’ve got some (10) AD8307’s on the way. Also about 40 other lots of aliexpress turds to snarf 

I have reworked my variation of the AD8307 board and ordered 5 of those too.

[Mark19960]

I thought "Uh, oh!" at the beginning, where he mentioned in passing about cutting your coax to a half wavelength, but his further remarks clarified his meaning.
Many hams are either too old & doddery, or too unfit to hang off a mast or ladder in the sky & measure at an antenna feedpoint, so it is a useful trick to use the characteristics of a half wavelength to repeat the antenna impedance inside the ham shack.

This is the often misquoted section of the Bird 43 manual that the CB crowd relies on when they justify their coax length arguments.
They would rather have a coiled length of coax on the floor because it's nearest to that magic length where the coax is nulled out and anything else is wrong!
They think there will be signal loss if the coax isn't that length, not because of the coiled up coax on the floor....

But! Bird says use this length of coax! Bird can't be wrong! Bird knows best!
Yeah.. it does say that... when using the meter to measure forward and reflected power and doing the maths to get the SWR...

That's something else too. Not only is the Bird 43 SACRED... but the manual is a SACRED TEXT!
 

[joeqsmith]

Did you say a while back you ordered another log amp to play with? Seems like you said you did.

Yes I’ve got some (10) AD8307’s on the way. Also about 40 other lots of aliexpress turds to snarf 

I have reworked my variation of the AD8307 board and ordered 5 of those too.

After seeing that one 8310 switch the way it did between states, I wonder if that part is more prone to this problem than the 07.   As you start to work on the project,  I'm interested if you see similar effects with any of the the 07s you end up using.   

I have that replacement 8310 on order but who knows when it will show if ever.

[xrunner]

So yesterday the new 2.4" white OLED was nice and bright, but this morning I could tell it was a bit dimmer than when I first got it. Then at lunch it looked like it would "blink" off and back on again very quickly. Then later it started having what looked like strobe lines across it. I was using USB to my PC because I was programming the new display layout all morning. I took it to a lab power supply and it (and the Uno board together were pulling ~ 450 mA. No no that isn't right.  The other test rig with two OLEDs only pulled ~ 50 mA.

OK all my other OLED displays can run off 5V. The information for this 2.4" OLED said nothing about Vcc being 5V OR --> 3.3V <-- (hint hint) just that Vcc is a certain pin. Nothing on the seller's page said it was 3.3V. I changed it to Vcc 3.3V and it has returned to a normal state.

But checking other displays like this I did notice that some said they were 3.3V 

Beware of all information supplied (or not clear) on any of these electronic parts! 

[bd139]

Did you say a while back you ordered another log amp to play with? Seems like you said you did.

Yes I’ve got some (10) AD8307’s on the way. Also about 40 other lots of aliexpress turds to snarf 

I have reworked my variation of the AD8307 board and ordered 5 of those too.

After seeing that one 8310 switch the way it did between states, I wonder if that part is more prone to this problem than the 07.   As you start to work on the project,  I'm interested if you see similar effects with any of the the 07s you end up using.   

I have that replacement 8310 on order but who knows when it will show if ever.

I will let you know when I find out.

It might be a long while yet because it turns out my new signal generator is a box of pain. Need to fight it first.

[mnementh]

Received the larger OLED display yesterday. Now I have real estate to work with.

It's supposed to work with SPI or I2C with reconfigurable jumpers. But of course I don't even need to state that it comes with no instruction sheet that tells which ones do what (except for a single one - R9). You might think that is the only one you have to jumper, but you would be wrong.

The seller has this on the Amazon page "SPI communication or I2C communication can be switched by configuring three resistors R3 R4 R5" But what about R9 - the one that's labelled to switch between ...  And are there any jumpers under the ribbon cable?   <------ YES! 

Fortunately I said to myself "Don't be stupid and trust these instructions". Looking elsewhere I found several people including The Defpom that had proper notes on the display. Geez - is it really that much trouble to include a piece of paper with the damn thing, or put the proper instructions on the seller page. I guess it is. 

Anyway - we'll test drive this thing today I hope.

Welcome to Ardu-HELL...   

mnem
Come on in... the water's fine. Slightly tainted with vomit and soul-tears, but you'll get used to it.

[joeqsmith]

Looking at a 10ms pulse, 100ms period.   When I moved up the sample rate,  I had set both filters' cutoff around 2kHz.  At 1ms, we will start to see some attenuation.  The detectors are certainly fast enough.    This slow sample rate and low cutoff are what limit the peak detect. 

[xrunner]

Another power meter build using AD8307s. This is his final video. He packaged the pickup and amps but didn't attempt to put the rest of it in a case. Basic display no bling.

[joeqsmith]

Another power meter build using AD8307s. This is his final video. He packaged the pickup and amps but didn't attempt to put the rest of it in a case. Basic display no bling.

Back on page 7,  I mentioned watching his videos and how he never finished the job.  I was never sure how accurate his setup actually was.   Was he showing the power to the load, forward only.   The parts I tried were much more linear with power but I wonder how flat his setup was over frequency as he never mentions how he compensated for it.   Then again, I may have dosed off. 

https://www.eevblog.com/forum/rf-microwave/cb-and-ham-radio-techs-love-their-bird-wattmeters/msg4232980/#msg4232980

Looked at a few other videos of people making their own.   Like the guy from down under, most never finish the job.  Accuracy?  What's that?      

[joeqsmith]

The technical paper mentions they used a 12-bit converter.  They have a hardware peak detect.   Page 13, they talk about displaying the RMS power.   Pg 12&13 both mention the 20 sample/second, 8Hz lowpass filter.     Pg 15 shows the fourier analysis from DC to 20kHz.    Pg 11 shows the block dia with a single 8-ch, 12-bit converter. 

https://wavenodedevelop.com/wp-content/uploads/2019/12/WaveNode_Family_Digital_Station_Monitor_12__2_2019.pdf

With a title of "Home of Precision R.F. Wattmeters" I would expect after reading their FAQ and skimming their other pages, I would have some idea on the error.   I'm sure it's there.. 

[xrunner]

Back on page 7,  I mentioned watching his videos and how he never finished the job.  I was never sure how accurate his setup actually was.   Was he showing the power to the load, forward only.   The parts I tried were much more linear with power but I wonder how flat his setup was over frequency as he never mentions how he compensated for it.   Then again, I may have dosed off. 

It isn't flat over power or frequency. As the freq. gets higher there is a drop-off but it isn't quite linear. Also, as you get into the higher power inputs ~0 dBm up to +13 dBm (this is where I stop) it also introduces another error which is combined with the other one. You can see this on the graph especially @ 440 MHz. I'm trying for 500 ...

That's what I've been looking at. I got sidetracked when I got my new display which is going to look fantastic, but I need to get back to my correction factor scheme. I won't be able to get it perfect but I will be able to get a decent accuracy without using hard-coded factors per band.

And mine will be packaged nice, like the last one. 

[joeqsmith]

He's showing the entire system, not just the detectors.  At the very start of Part 1, he targets the HF bands only.   I suspect his coupler contributes a lot more error than the detector but he never goes into it with the final setup.  Closest is Part 3, about mid way in where he shows some data for the coupler from 3MHz to 21MHz. 

I was hoping to see him do some sort of sweep of power and frequency as it appeared he had no way to compensate for the error outside of what he mentions in that last video.  At 7mins in where he shows the error, he never mentions the freq.   I doubt that data will be the same over 3-21MHz he wanted to run at.    Then again, maybe the errors were so small, it wasn't a concern for him. 

***
Noticed you show the 10 where he is using the 07.

[xrunner]

Noticed you show the 10 where he is using the 07.

Yes sir. My parts are AD8310 which are rated up 440 MHz. The 8307 is rated up to 500 MHz. 

[joeqsmith]

Lots of YT vids for Fred Roll WW4D.   Hams saving the world 

[joeqsmith]

Noticed you show the 10 where he is using the 07.

Yes sir. My parts are AD8310 which are rated up 440 MHz. The 8307 is rated up to 500 MHz. 

True but he was only attempting to get the setup working to 21MHz.   Still, a pretty good goal. 

[xrunner]

True but he was only attempting to get the setup working to 21MHz.   Still, a pretty good goal.

I should have reduced expectations and said I'd stop at 30 MHz. I'd be done by now and surpassed that guy! 

[joeqsmith]

True but he was only attempting to get the setup working to 21MHz.   Still, a pretty good goal.

I should have reduced expectations and said I'd stop at 30 MHz. I'd be done by now and surpassed that guy! 

Maybe.  Going in-line like he did adds to the mix.  I think he said he was wanting 100W.   I wonder if you could design a 3MHz to 500MHz, 100W slug for the Bird.  That may pay for a few hobby projects. 

[xrunner]

Maybe.  Going in-line like he did adds to the mix.  I think he said he was wanting 100W.   I wonder if you could design a 3MHz to 500MHz, 100W slug for the Bird.  That may pay for a few hobby projects.

The problem with the slug is, I think, more about the casing than the coupling inside. You got to do some precise machining with metal parts. I don't have that capability. I can do 3D printing but that won't cut it for the Bird.

I should be able to post my solution for correction factors tomorrow. I think I've gone about as far as I want to go with it. I want to move on to my fancy display. Now I know for that I can out-do what that guy did. I mean I'll even have icons on the screen.