CB and Ham Radio Techs Love Their Bird Wattmeters

[A.Z.]

Probing from the copper side to the adhesive, if I touch off on the glue it is not conductive.  The black material is suspended in the adhesive.  If you move the glue around, the black material moves with it.  Maybe just a sprinkle of course carbon mixed in.  Can't add too much or the adhesive won't have enough surface area to stick. 

I wonder if the "copper tape" presents some capacitance at RF due to the adhesive layer, I mean if one sticks some "tape" over another layer ...

[xrunner]

Probing from the copper side to the adhesive, if I touch off on the glue it is not conductive.  The black material is suspended in the adhesive.  If you move the glue around, the black material moves with it.  Maybe just a sprinkle of course carbon mixed in.  Can't add too much or the adhesive won't have enough surface area to stick. 

My image is attached. It also shows black specks of an unknown substance on the sticky side. The pic shows the adhesive side on the left and the uncoated side of the tape on the right.

I wonder if the "copper tape" presents some capacitance at RF due to the adhesive layer, I mean if one sticks some "tape" over another layer ...

Well you know how it goes. Most electronic components have properties of other types of components. Resistors have some inductance and capacitance, capacitors have some resistance and inductance ... and so on. So of course it will exhibit some capacitance.

But I don't understand what you want to do. Do you mean stick the adhesive side of one piece of tape to the copper side of another? Or do you mean stick two pieces of tape together adhesive to adhesive? But the adhesive is conductive. The dielectric material in a capacitor is not. It will mainly create a resistor with probably between 0 and 1 ohms.

Remember you guys are way smarter than me so please take that into account. 

[kj7e]

Not sure how I ever missed this thread.  The Bird 43 is good for a second opinion, IMO.  I much prefer my LP-100 for accuracy and LP-500 station monitor for everything else.  That said, I did a few videos for the fun of it over the years.  LP-500 vs Bird 43.

https://youtu.be/3FhwtYpVrqQ?si=kGshY90QjBBg5d16


Of course, what would this be without modifications.  Here I added a custom modification to prevent exceeding the FCC power limit;

https://youtu.be/FYLvDVBtUi0?si=MpU6AskIPWmjiV5k

[joeqsmith]

Not sure how I ever missed this thread.

Welcome aboard.  I like your calibrated paper approach to measuring power.  Looks like you play with some RC planes and bicycles as well.  I'll check out your channel. 

[xrunner]

Not sure how I ever missed this thread.

It was pretty active at the start what with the Bird defenders and antagonists going toe-to-toe. Mostly calmed down now but since "Bird" was mentioned again it might get hot. 

[xrunner]

Gathering parts for wiring & final assembly.

[xrunner]

The coax jumpers are tight and I will probably try another case later but for now it's "Full Speed Ahead!". 

[xrunner]

Wiring progress for today. I made up female dupont connectors on the ends of some wiring so I will be able to unplug power to the log amps and also unplug the output voltage from either one of them, if needed for testing purposes.

[joeqsmith]

Bends don't look near as bad in this photo.   

[xrunner]

Yea I got them to sit a bit better. The bends coming off the coupler are about as tight as I'm comfortable with but I think it's OK.

I think I found the couplers on Ebay in June and started it all from that point, so if I can get this project finished by Dec 31 it'll be seven months. 

[xrunner]

Breadboard eliminated, just a few more components and wires to connect.

[xrunner]

I finished the wiring and decided to have headers for all the inputs and outputs so they are removable. However, this decision to use headers made my case now not have enough inside height so I'll have to go back and re-do some 3D printed case parts. Not a large deal but that's how things roll.

The meter seemed to work at first glance. However, upon testing with an rf input of several watts it was obvious that there was a problem with the indicated rf power. I didn't find anything wrong with the wiring I did on the Due proto board. I was certain I didn't muck up the program testing things last time I ran it, but I checked and downloaded the software again to be sure. I proceeded to move down to the log amps because I didn't see any Vout from either one at the A0 or A1 inputs. In fact, the voltage input to analog channel A0 and A1 seemed to be floating though I wasn't sure how that issue could have arisen. Oh no please don't tell me ... no it can't be they're zapped? 

I opened up the case on the channel one log amp and observed that the center conductor of the Vout cable had pulled away from the solder pad. I then opened up the other log amp and saw that the same thing had happened. Obviously there was a lot more twisting force on the cable than I had anticipated.

I shorted the center conductor to the Vout pad on the log amp with a pin and re-transmitted my test signal. At 146 MHz, the FWD power registered a decent reading, off a bit due to changes needed in all the cal factors, so I'm confident the project will be good to go after I repair the current problem.

What I think I'll do is split the shield into a left and right conductor, and that will anchor it better. It won't be tugged on anymore.

But the bright side is that it appears to be a functional meter from what few tests I've done.

[joeqsmith]

I made an attempt to add the ground strap to the coax to the Nissei RS-70. 

[xrunner]

Good work on the meter, might help somebody out there.

I reworked the Vout cables and now the center conductor should be held tight. I changed the cal factor for the 2 meter band a few times to get it closer.  I didn't spend a whole lot of time on it yet because the case isn't completely closed. I have to work on the new case parts now.

But the power is reading pretty close to what I last measured the output of the Baofeng to be in the 2 meter ham band. On high it was 4.6 W (depending on the charge of the battery) as measured with my hp 437B power meter. The project meter indicates 4.8 W. On low power the project meter also measures about 1.8 W which is only a few tenths of a watt from what it should be. So for now I'm happy with that.

Now to work on re-dimensioning the front, back, and side risers. There also won't be so many vent slots on the back panel because it's too much trouble to get them cut out after applying copper tape. 

[joeqsmith]

Video demonstrating using attenuators for a load.  Rather than a VNA, he uses a scope with TDR.  Warning,  I cringed a lot during the video.....

[vk6zgo]

Video demonstrating using attenuators for a load.  Rather than a VNA, he uses a scope with TDR.  Warning,  I cringed a lot during the video.....

Yes, he does rather like screwing them on the wrong way---that's why I like "N" connectors---you have to be pretty brutal to hurt them.
The information is good, but he "waffles on a lot" to get it over.

In the field it is often necessary to present the test equipment or DUT with a reasonably correct load, so if someone forgot to return the load to the equipment box or "cooked" it, & you are several thousand km from home, it is nice to be able to get quite close to a calibration load accuracy with two 40dB pads in cascade.

Another scenario is if you are working at a company which is quite poor (or miserly) where you may not have a calibration load & need something to "Second think" the Bird test load specs.

[metrologist]

Yes, he does rather like screwing them on the wrong way---that's why I like "N" connectors---you have to be pretty brutal to hurt them.

You are not supposed to rotate the body, doing it that way wears out the center conductors, rotate the nut instead.

[joeqsmith]

Yes, he does rather like screwing them on the wrong way---that's why I like "N" connectors---you have to be pretty brutal to hurt them.

You are not supposed to rotate the body, doing it that way wears out the center conductors, rotate the nut instead.

It can do a lot more than wear out the parts, it can easily damage them. 

https://www.microwaves101.com/encyclopedias/how-to-not-trash-a-calibration-kit

[metrologist]

Yes, he does rather like screwing them on the wrong way---that's why I like "N" connectors---you have to be pretty brutal to hurt them.

You are not supposed to rotate the body, doing it that way wears out the center conductors, rotate the nut instead.

It can do a lot more than wear out the parts, it can easily damage them. 

https://www.microwaves101.com/encyclopedias/how-to-not-trash-a-calibration-kit

That's great. I try to learn something new every day.

"Mayor McCheese:
Once an ad campaign for junk food, now the perfect nickname for your boss, especially if he is a big sloppy eater. Note the resemblance? BTW, Mayor McCheese is all over the internet, including a parody of "Me and Bobby McGee"... "nugget's just another word, for no meat left to use...""

And there are a lot of ways to damage these components. Other than bent pins from ham fisting them together, we often see signs of over torque and cross threading. Nobody likes a cross threader 

This is not recommended:
"A handy RF connector wrench is made by grinding (on a bench grinder) down the jaws of a small crescent wrench thin enough that it can grasp the flat on a SMA barrel."

We give away a half-dollar size stainless disc with notches cut around the perimiter for a handy RF connector wrench. The open end wrenches are not a good idea either.

[xrunner]

Yes, he does rather like screwing them on the wrong way---that's why I like "N" connectors---you have to be pretty brutal to hurt them.

You are not supposed to rotate the body, doing it that way wears out the center conductors, rotate the nut instead.

It can do a lot more than wear out the parts, it can easily damage them. 

https://www.microwaves101.com/encyclopedias/how-to-not-trash-a-calibration-kit

If you do it like that you're screwed!     

[vk6zgo]

Yes, he does rather like screwing them on the wrong way---that's why I like "N" connectors---you have to be pretty brutal to hurt them.

You are not supposed to rotate the body, doing it that way wears out the center conductors, rotate the nut instead.

That's what I meant!
With the very tiny female to female "barrels" I do often rotate the body initially, to engage the first thread, then complete the job the correct way.
It is perilously easy to drop the little shits of things on the floor, & I'm too old to grovel down there.

[xrunner]

Re-designed (taller) case panels printed - new ones on left side in pic. Inching closer to a fully assembled project. 

[joeqsmith]

The open end wrenches are not a good idea either.

I use open end wrenches frequently with RF connectors to hold all the bits while I set the torque, or loosen them.  Now I wouldn't suggest using them to torque anything.  That's a bad idea. 

Yes, he does rather like screwing them on the wrong way---that's why I like "N" connectors---you have to be pretty brutal to hurt them.

You are not supposed to rotate the body, doing it that way wears out the center conductors, rotate the nut instead.

That's what I meant!

I assumed so.  That guy was going to town on them. 

[metrologist]

Yes, he does rather like screwing them on the wrong way---that's why I like "N" connectors---you have to be pretty brutal to hurt them.

You are not supposed to rotate the body, doing it that way wears out the center conductors, rotate the nut instead.

That's what I meant!
With the very tiny female to female "barrels" I do often rotate the body initially, to engage the first thread, then complete the job the correct way.
It is perilously easy to drop the little shits of things on the floor, & I'm too old to grovel down there.

It's quite common for regular users to become proficient at making the connection, the wrong way, but without gross damage. It's bad enough there is axial sliding friction, but as you get into V, W and 0.8mm connectors, you want to avoid as much of that as possible.

[joeqsmith]

The metrology grade connectors HP used for their standards with those fingers are far more delicate than your typical Chinese connector.   One wrong twist may render the $10,000 USD useless.       

At home, I will try and buy good used adapters if possible.  The last used one I bought was a 7mm to N.  Got lucky in that case.  Looked like who owned it, kept their grubby fingers off the mating surfaces.  Lately used prices are higher or close to new and not worth the risk.