CB and Ham Radio Techs Love Their Bird Wattmeters

[xrunner]

I like using PCB material for cheap and dirty cases.   Instant shield.70 isn't looking so bad now.   

Next time I'll try to find a larger case like the type I used for the two previous power meters I made in this thread. Like the case type shown in the pic. It has a wrap-around metal box that accepts a slide-in PCB (or 3D printed mounting plate).

The only parts that need copper tape are the back of the front and rear panels, which are 3D printed to accommodate the buttons and OLED display. That's no big deal to do.

But we'll persevere here and complete the shielding. Then I can go on to getting it all wired up and move on to the funner parts of the project. 

[joeqsmith]

The only parts that need copper tape are the back of the front and rear panels, ....

Why does it require any shielding?   Your detectors and coupler are already shielded.  Are you concerned about the emissions off your digital stuff?  If so, what is coming off that display?   

[joeqsmith]

So this Dosy TFC3001 could be a copycat improved version of the low end meter looked at:

https://www2.randl.com/index.php?main_page=product_info&cPath=15_8100&products_id=38712

The attached photo was taken from the following video.  Looks like their coupler also uses the 4 rods.  Meter movements are almost identical.   The mfg's website makes no mention of the frequency range or expected accuracy.  At a glance, seems they are still peddling this garbage to the unsuspecting hams.  Maybe someone has one that can post data for theirs.  At $200, maybe it is usable but I doubt it.   

https://www.dosy.com/store-products/inline-watt-meters-3-watt-ranges-1000-watts-max-3-meters

[xrunner]

Why does it require any shielding?   Your detectors and coupler are already shielded.  Are you concerned about the emissions off your digital stuff?  If so, what is coming off that display?

Why? Best practices design if nothing else. It just makes sense to me to have this type of project in a shielded box. Doesn't it make basic design sense to you?

I mean, let's put it this way - if I didn't put this in a shielded enclosure, what do you think the peanut gallery would say to me? I'll tell you exactly what -"You should have put your project in a shielded box if it's sitting right next to high power radios". 

[A.Z.]

that dosy critter costs too much, pick this one instead

https://www.amazon.com/Astatic-302-PDC2-Field-Strength-Meter/dp/B000KEUFME

LOL

[joeqsmith]

Why does it require any shielding?   Your detectors and coupler are already shielded.  Are you concerned about the emissions off your digital stuff?  If so, what is coming off that display?

Why? Best practices design if nothing else. It just makes sense to me to have this type of project in a shielded box. Doesn't it make basic design sense to you?

I mean, let's put it this way - if I didn't put this in a shielded enclosure, what do you think the peanut gallery would say to me? I'll tell you exactly what -"You should have put your project in a shielded box if it's sitting right next to high power radios". 

To me, it doesn't make much sense.  All of your RF signals are already enclosed.  If there was a concern about emissions, you may want to try and find a way to shield that gaping hole where the display is, not to mention the emissions from the display itself.   If it is susceptibility of the little digital board, that may make more sense. 

I would assume the high powered radios are radiating off the antenna which is not pointed back towards the lab.   If they do produce a lot of emissions in the lab, maybe that should be addressed rather than trying to harden everything else. 

From a professional work stand point,  typically I will test my designs in the chamber with no shielding.  If I can get them to pass there, typically going forward things are smooth sailing.  Current career is pretty tame so not normally a big deal. 

Now granted the nutter butter peanut butter crunches may look at all that waveguide frequency extender stuff I am playing with and suggest an enclosure would have greatly improved things.  After all, that thing is a mess compared to what you are doing and working at much higher frequencies and fairly low noise.   The only person I think that called it out wasn't suggesting the lack of a shielded case was the problem but rather the software.

https://www.eevblog.com/forum/rf-microwave/experimenting-with-waveguides-using-the-litevna/msg4797743/#msg4797743

So, sure, it is now in a somewhat shielded box.  Not for RF performance but instead, mechanical stability and size reduction.   

[joeqsmith]

that dosy critter costs too much, pick this one instead

https://www.amazon.com/Astatic-302-PDC2-Field-Strength-Meter/dp/B000KEUFME

LOL

That's pretty low end, like mine. 

Note how they don't show the frequency range or accuracy.  Looking at some reviews, looks like at least a few hams purchased one.  One is calling it an SWR meter.  Like that one I played with, guessing it would do fine for that.   Even my old Mars SWR meter works fine for the HF bands.   Find me a cheap meter that states the frequency range and power accuracy.   Think Watts, not SWR.   

****
One of the reviews from the hams talks about the ease of reading the power.  Maybe it works good enough. 

Something between yours and mind.
Comet CN-501H2 CN501-H2 Original Daiwa SWR Power Meter, AVG Reading, 2KW Power (1.8~60MHz, 1 KW 144MHz)

Maybe it's 60MHz, maybe 144MHz.  Connectors are solid, unlike the funky air dielectric ones used in that Chinese meter that doesn't work. 


https://www.amazon.com/CN-501H2-CN501-H2-Original-Reading-1-8-60MHz/dp/B096T8W2CB/ref=m_crc_dp_lf_d_t1_sccl_3_12/141-6969575-4949011?pd_rd_w=us9mP&content-id=amzn1.sym.76a0b561-a7b4-41dc-9467-a85a2fa27c1c&pf_rd_p=76a0b561-a7b4-41dc-9467-a85a2fa27c1c&pf_rd_r=8SW603CZ3DA8XM2GAWB3&pd_rd_wg=PaCYZ&pd_rd_r=32fd0584-b45a-4c4e-91df-4611ab883fce&pd_rd_i=B096T8W2CB&psc=1

[xrunner]

To me, it doesn't make much sense.

Opinion noted, but to me it does make sense. But thanks for your opinion.

[joeqsmith]

To me, it doesn't make much sense.

Opinion noted, but to me it does make sense. But thanks for your opinion.

I find it odd you wouldn't explain what your concerns are and why. 

[xrunner]

I find it odd you wouldn't explain what your concerns are and why.

LOL I've been here a long time and I have leaned on this forum when to debate something and when not to. I don't see any reason it would make any difference to you in the end so I will let it go. But we're still, like, friends and all. 

[joeqsmith]

I would assume you have reasons for your choices.  I am just asking what they are.

[vk6zgo]

So this Dosy TFC3001 could be a copycat improved version of the low end meter looked at:

https://www2.randl.com/index.php?main_page=product_info&cPath=15_8100&products_id=38712

The attached photo was taken from the following video.  Looks like their coupler also uses the 4 rods.  Meter movements are almost identical.   The mfg's website makes no mention of the frequency range or expected accuracy.  At a glance, seems they are still peddling this garbage to the unsuspecting hams.  Maybe someone has one that can post data for theirs.  At $200, maybe it is usable but I doubt it.   

https://www.dosy.com/store-products/inline-watt-meters-3-watt-ranges-1000-watts-max-3-meters

Those testers having an AM modulation monitor function is pretty much a dead giveaway that they are aimed at the North American CB market.

AM is a rare & specialised mode amongst hams, & is not even the mode of choice of most HF CBers outside North America.
In Broadcasting, Modulation Monitors are a separate device especially designed for the job, & a cruddy ''add-on" for a power/SWR meter would not be considered.

[joeqsmith]

Those testers having an AM modulation monitor function is pretty much a dead giveaway that they are aimed at the North American CB market.

North American CBers with kW amplifiers

[vk6zgo]

Yep!

On YouTube they definitely say they have them & use them for "keydown" tests.
I think they are kidding themselves, but it keeps them happy.

Hams seldom use AM, so what use would the extra function be to them?

[xrunner]

Yep!

On YouTube they definitely say they have them & use them for "keydown" tests.
I think they are kidding themselves, but it keeps them happy.

Hams seldom use AM, so what use would the extra function be to them?

The only mode I've used in the last few years is FT8 (and it's predecessors). I'm at 199 DX entities right now. As soon as I get 1 more I'll probably quit because it doesn't really interest me anymore.

[joeqsmith]

Yep!

On YouTube they definitely say they have them & use them for "keydown" tests.
I think they are kidding themselves, but it keeps them happy.

Hams seldom use AM, so what use would the extra function be to them?

Not being a ham, I'll take your word about their seldom use of AM.   That old Drake I have supports it.  It even supports CW which I suspect is also seldom used.   

As for the hams use of extra functions,  not too long ago we had, I assume a ham, visit this sight who was attempting to install some software I wrote.  During their tantrum, one thing they did touch on was the many worthless features the software has ( my interpretation).  From the ham's perspective, I can certainly understand.  From my limited interaction with hams,  the majority only want to measure SWR (in some cases 3 places beyond the decimal).     So why would they want to download such feature rich software that they will never utilize?        Maybe the same reason a novice playing with electronics and no formal education feels the need to own a Fluke 87V?  Human nature?  Who knows.... who cares...    I was interested in how the Watt meter function performs. 

[joeqsmith]

Ham demonstrating the Bird 4381.  Page 17 in the manual explains the AM modulation feature.  Why would a ham want so many features they will never use? 

https://birdrf.com/~/media/Bird/Files/PDF/Discontinued-Manuals/920-4380s_rf-power-analyst.ashx

[EE4all]

It's almost like hams might have electronics interests sometimes as well. Who cares.

[joeqsmith]

It's almost like hams might have electronics interests sometimes as well. Who cares.

You must as you felt the need to post.

[EE4all]

Yes, this thread keeps popping to my "show new replies to my posts," link since I participated in this thread earlier. Then I see that nonsense. Is there a way to keep a thread from popping into that list if you have posted to a thread ? I need to research how to do it.

[metrologist]

Not everyone starts riding on a VMAX. 

I started out on a Suzuki AS50.

Quite a respectable place to start. But it's no Bird 

Those testers having an AM modulation monitor function is pretty much a dead giveaway that they are aimed at the North American CB market.

North American CBers with kW amplifiers

LoL. You really think CB'ers need anything more for what they're doing?

I tell you what, 40 40 Mobile coming at you from the dock of the bay right in the heart of silly cone valley running the bowl.

kW amplifiers? They turn their suburbans into multi-element beams and run tens of kW. We think 40 40 Mobile's burb filled with those sloppy splatter boxes caused his cancer, rest his soul...

. . . . . . .

That Dosy is overpriced but certainly served its intended market just perfectly, and their marketing surely earns that margin.

[joeqsmith]

Not everyone starts riding on a VMAX. 

I started out on a Suzuki AS50.

Quite a respectable place to start. But it's no Bird 

My GS vs VMax.  There's always something better out there. 

LoL. You really think CB'ers need anything more for what they're doing?

After watching several videos of the CB contests and some of the interviews early on in this thread, yes. 

That Dosy is overpriced but certainly served its intended market just perfectly, and their marketing surely earns that margin.

Cost today would be closer to $450.  $200 is a steal!! 

[joeqsmith]

Thinking of plastic cases, that photo of my poor man's frequency extender showed another good example, the LiteVNA.   Like your homemade Watt meter, some of the sensitive areas use an internal shield but the case is all plastic.    Looking around my office, I have a TV tuner attached to the PC over USB.  Plastic case.. 

Normally, I don't have a lot of problems with RF effecting anything in my office.  Recently I noted that Dave's 121GW was whacking out when I was attempting to use it.  Had to drag out the foil.  If I am testing ignitions (gasoline engine stuff),  my USB peripherals have a problem.  The mice will reset or go offline.  USB, such a poorly designed standard for industrial use.......

[metrologist]

My GS vs VMax.  There's always something better out there. 

Back in the day, the Blackbird tempted me. When I got back into riding, the latest Busa was showing well on the floor. I thought I was going to get an S1000RR, but my knees couldn't take it. The nuts running the H2R for clicks and bits were fun to watch for a while, as was the evolution of Max Wrist.

After watching several videos of the CB contests and some of the interviews early on in this thread, yes. 

Well, you can't really refer to those folks as CB'ers, and I'm sure they're not tuning with a Dosy. I bet the middle of the bell are your 20W overmodulated radios to a high swing 2W driving a 400W linear truckers running some base load short antenna. It's not gonna matter if your modulation or reflected power is reading 20% off. The bigger concern is, how long should your coax to the antenna be to get a proper reading. 

Cost today would be closer to $450.  $200 is a steal!!

Indeed! I use a couple cross needle meters and tune with a scope. Maybe I'll dust off that 8901B for something more important. I got's the golden screwdriver <bucktooth emoji>

[xrunner]

Not too much more to do on the shielding. The top, bottom, and faceplates will all touch copper-to-copper when assembled. I will run one copper braid bonding wire from the electronics ground to the copper shield by soldering it to a piece of copper tape.

I did find some aluminum cases on Amazon that would work for the size I need. I think I ran across some before but I decided to get the plastic case because I was turned off by the price. But, they are available -

Amazon aluminum case