Electronics > RF, Microwave, Ham Radio

CB and Ham Radio Techs Love Their Bird Wattmeters

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joeqsmith:
I've been reading various papers and patents on directional couplers.   Some from the 70s to current.   Have a look at the construction:

https://patents.google.com/patent/US11309668B2/en

joeqsmith:
This one's pretty interesting.

https://patents.google.com/patent/US9105954

xrunner:
Received two used Hirose HCS2-110-F SMA coaxial switches. They go "click" when 12V is correctly applied and draw 90 mA.

That is all I know at the moment, more testing will occur ...

fourfathom:
Yes, that last patent is interesting to be sure.

Here is a stupid/simple SWR bridge I made (but haven't stuffed the board or tested it yet).  It uses the classic two-transformer design, but I scaled up the sense impedance to increase the sensitivity while keeping low loading.  I used a diode-doubler detector circuit and then a resistive divider to keep the output within range of my 0-3V A-D input.  It's designed for a 10 MHz sub-one-Watt transmitter for a drift-buoy hobby project, so the likely frequency limits aren't a problem.  It's not designed to be a precision measuring device, just something that will let me check and report basic antenna matching and power output.

I'm using the bridge version with the center-tapped transformers.  The more typical one has no taps, but center taps give you a very slightly better performance.

joeqsmith:

--- Quote from: xrunner on August 18, 2022, 09:16:53 pm ---Received two used Hirose HCS2-110-F SMA coaxial switches. They go "click" when 12V is correctly applied and draw 90 mA.

--- End quote ---

Noticed the low SN has a catch diode.   Was it later added internally?



--- Quote from: fourfathom on August 18, 2022, 10:59:25 pm ---Yes, that last patent is interesting to be sure.

Here is a stupid/simple SWR bridge I made (but haven't stuffed the board or tested it yet).  It uses the classic two-transformer design, but I scaled up the sense impedance to increase the sensitivity while keeping low loading.  I used a diode-doubler detector circuit and then a resistive divider to keep the output within range of my 0-3V A-D input.  It's designed for a 10 MHz sub-one-Watt transmitter for a drift-buoy hobby project, so the likely frequency limits aren't a problem.  It's not designed to be a precision measuring device, just something that will let me check and report basic antenna matching and power output.

I'm using the bridge version with the center-tapped transformers.  The more typical one has no taps, but center taps give you a very slightly better performance.

--- End quote ---

IMO, nothing I show was very complex.  The coupler is the heart of what I was attempting to demonstrate.   Making something that would cover the frequency range of that 07 demo board and not require fitting would be much more difficult. 

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