CB and Ham Radio Techs Love Their Bird Wattmeters

[xrunner]

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 

Yea, and these buttons I have, just el-cheapo things, aren't directly mountable to a panel in an easy way. You have to solder to a PCB and then mount that PCB to the panel. I think I'm going to get some better quality buttons that can be through-hole mounted. Quality is job One. 

On another note, have you experimented with any of the e-paper displays? I have never had one but I think they look really nice, I understand they are not bright on their own. Also might not update quite fast enough. Just an idea. What do you think about an e-paper display for an instrument if it updates fast enough?

[joeqsmith]

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 

In the 80s we had the Exormax, Exorsizer and old HP 64000 with some huge (physically large) drive to do our development work.  The 64000 stations were networked together over GPIB to the drive and a printer.   There wasn't much available for the hobbyist.   I designed and built an ICE for the Motorola 68701.   We would scrap the microcontrollers once they had been used too many times and I would use these for my home projects.   A few years ago, I built a transient generator using wire-wrap and the 6801 just to see if things were as bad as I had remembered.  They were!   

[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 

Yea, and these buttons I have, just el-cheapo things, aren't directly mountable to a panel in an easy way. You have to solder to a PCB and then mount that PCB to the panel. I think I'm going to get some better quality buttons that can be through-hole mounted. Quality is job One. 

On another note, have you experimented with any of the e-paper displays? I have never had one but I think they look really nice, I understand they are not bright on their own. Also might not update quite fast enough. Just an idea. What do you think about an e-paper display for an instrument if it updates fast enough?

I would probably go insane with an epaper display. Even my kindle which is fairly quick makes me want to throw it out of the window 

[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 

In the 80s we had the Exormax, Exorsizer and old HP 64000 with some huge (physically large) drive to do our development work.  The 64000 stations were networked together over GPIB to the drive and a printer.   There wasn't much available for the hobbyist.   I designed and built an ICE for the Motorola 68701.   We would scrap the microcontrollers once they had been used too many times and I would use these for my home projects.   A few years ago, I built a transient generator using wire-wrap and the 6801 just to see if things were as bad as I had remembered.  They were!

Yep totally agree. I find anything old and digital was horrible. Analogue stuff is still fine but digital yuck. In circuit emulators were amazing for development but still horrible compared to some of the modern debuggers over JTAG etc.

Actually on that, a few years back I found the strip board Z80 I built when I was a teenager. The thing was programmed via dip switches into a tiny SRAM. I actually managed to power it up and switch in a program that just shifted a bit across a PIO when you pressed the INT button. Took me an hour to get it right. It went in the trash after that. Never wanted to see it again 

I’m a fan of modern comforts 

[xrunner]

I would probably go insane with an epaper display. Even my kindle which is fairly quick makes me want to throw it out of the window 

Yea they seemed a little pokey slow from what I saw in videos. I'll pull my storage drawer of displays and figure out the best choice out of that bunch.

I guess I'd best get the program to output the right answers first 

Back to that task ...

[joeqsmith]

In circuit emulators were amazing for development but still horrible compared to some of the modern debuggers over JTAG etc.

I used the CPU32 and wrote some software for the BDM interface.  Wrote a little test code for a different Motorola part using JTAG.  That was in the 90s.  It seems things are better today with the cheap micros.   

I guess I'd best get the program to output the right answers first 

I still haven't made it that far.  Results from my last tests were dismal. I scrapped the design.  The paint was still drying.    

While I sort out my next plan for a device I have no use for, here's an article written by an employee at Bird.
https://www.electronicdesign.com/home/article/21201015/directional-power-measurements-and-the-effects-of-directivity

[joeqsmith]

Chopping up the AD8302 gain phase detector to add a 16dBish attenuator to the front end of both channels. 

[xrunner]

Amazon is running late so I won't get my better pushbutton switches till tomorrow. Nevertheless, I think I'll have something to show tomorrow regarding my progress.

Probably. More likely than not, barring unforseen circumstances. I'd say more than a 72% chance. OK 50% ... 

[joeqsmith]

I like those odds. 

Before I do anything with AD8302,  I wanted to make another coupler better suited for the next experiments.  I shaved 21dB off the coupling which hurt the directivity at the higher end.   May have improved it at the lower end.  Looks like the isolation is getting close to the LiteVNAs limit.   

[joeqsmith]

Using the Lite to look at 100 averages of the forward isolation.  Too bad the entire frequency range isn't that good.     

[xrunner]

It doesn't look pretty yet, but I have a usable digital RF power meter for a range -70 to +13 dBm.

The RF input is coming from my Agilent 8648A. The AD8310 board is receiving RF and the output Vo goes to a microcontroller analog input referenced to 3.3 V. I decided to acquire three Vo samples (100 mS apart) and average them before applying any calculations per reading. Two buttons (using interrupts) are for the operator: the left chooses the band for the correction factor, the right chooses the external attenuation.

The selectable bands with correction factors applied are -

HF
6m
2m
1.25m
70 cm
Wide

"Wide" means no correction factor in case you want to characterize or observe the uncorrected AD8310 response.

The ext. attenuation choices are 0 through 50 in 10 dB steps. This corrects for any ext. attenuator you may need to use to safely measure higher powers over +13 dBm.

The band and ext. att. information is displayed as well as the calculated power taking all factors into account. I thought I'd try a yellow over blue OLED display for starters. I think it's too small so I'll be changing that this weekend.

A few quick initial tests: input a -20 dBm signal at both an HF freq. of 30 MHz and the highest band at 440 MHz. As you can see, the calculated power reading with correction factor (see previous posts with spreadsheet) is within 0.1 dB at HF and 0.2 dB at 440 MHz. Other spot checks were also very good. It's looking to be a very usable meter. I'm going to do more tests with higher power inputs with external attenuators in-line to check the ext. att. correction. I don't foresee any issues arising there. Will report back on this.

[joeqsmith]

It looks nice enough to me. 

I powered up the next eval board tonight and was pleasantly greeted by a blue LED.    I've no idea if the IC is a clone or not but it appears to behave like the Analog Devices data sheet shows.   

[xrunner]

Oh wow blue - nice catch on that one! Looks like the suppliers of these little PCBs might be heading toward RGB lighing like the PC builders use.   

Guess I'll be dusting off the 3D printer this weekend so I can start working on case parts for this project. I got an aluminum case coming but I'll make custom front and back panels for it, and a slide-in platform for the PCBs. I already have the Fusion 360 files from the last one I did (for a different size case) but otherwise it's the same type of general design. I just need to make some new holes and re-dimension.

I also got a 1.3" blue OLED for the display to swap in, better push button switches, and a pigtail adapter to convert the SMA to SO-239 panel mount for the RF input ('cause that's what hams like to use ya know).

[xrunner]

This weekend is "Field Day" where hams are supposed to go outside and make contacts. The temp here will be 105 F (40.5 C) like it was yesterday. No way in Hell am I going to even visit any filed day activities. 

I'm staying inside and working on my power meter! 

[bd139]

Mmm roast ham 

[joeqsmith]

The one day hams take no longer hold their coveted Bird meters captive on their benches.   If you decide to go bird watching, be sure you take some pictures.   

My new coupler's output connector.   

[A.Z.]

The one day hams take no longer hold their coveted Bird meters captive on their benches.   If you decide to go bird watching, be sure you take some pictures.   

My new coupler's output connector.   

TOTALLY BUSTED !

)

[xrunner]

More parts arrived -

Aluminum project case (bought two)

Better push button switches (panel mount as well). Couldn't get these on Amazon without red caps. Will probably change those to another color.

Blue 128 x 64 OLED display

RF pigtail adapter

*****

Trap for young players (as Dave sez)

Check the pic below. I had a blue OLED in my display box, but testing it revealed I had forgotten it had a slight flaw, so I ordered another one. I was about to plug it into the breadboard but something caught my eye. It's the same functional part, but look at the pin labels. The VDD and GND pins on the new part are reversed from the old one (the labels on both parts are correct).

 

[bd139]

Ok found some high end Bird Shit today at a hamfest.

10KW anyone? 

The connector is larger than my load.

Apologies for the sideways. On mobile device.

[xrunner]

Really nice - doubles as an anvil.

Perfect birthday gift for your local CB friend. 

The RF adapter/connector probably costs more than the amp you are using. 

[vk6zgo]

Really nice - doubles as an anvil.

Perfect birthday gift for your local CB friend. 

The RF adapter/connector probably costs more than the amp you are using. 

And there was probably one in the equipment store at the station the load came from---maybe ending up unwanted & sent to landfill!
It wouldn't be that hard to fabricate an adaptor, though--from memory they don't use any magic techniques!
If it was cheap enough, most people wouldn't care about the overkill in power rating.

[A.Z.]

Really nice - doubles as an anvil.

Perfect birthday gift for your local CB friend. 

The RF adapter/connector probably costs more than the amp you are using. 

nope, not as an anvil, and it isn't a dummy load at all, it was used by some CB to keep the shack warm during winter, remember, Bird stuff is good even for heating the shack !

[bd139]

You might be on to something there 

[joeqsmith]

That's a nice find.   

The video I had linked with the ham using elements from a hot water heater (and wondering why it did not have decent wideband performance) just needed to take the next step.   In the attached picture we can see a young ham working on their load.   I suspect this youngster later became the chief engineer for Bird.

[bd139]

Hahaha