Uber simple power meter?

[W7SOE]

Analog Devices AD8307:

Low Cost DC-500 MHz, 92 dB
Logarithmic Amplifier

See attached image from datasheet, I am thinking of strapping this to a micro with ADC and adding an LCD.  Looks like an easy digital power meter.

Rich

[W7SOE]

Ooops, it's been done.

Rich

[WBear2GCR]

Why work so hard on the display end?
Seems like a cheeapo DVM will do a good enough job on the display side??
Or, if you want better, one of those LCD digital panel meters??

No?

Is there a commercial product using this chip?

          _-_-bear

[KF1Z]

Sure, why not..... people reinvent the wheel every day....  :-)

Would be nice and easy to use two devices, and be able to monitor reflected and forward power....

Using the mentioned LCD VM, the whole project would only cost about $50.

Those ICs are $10. each at digikey.

And, could easily be scaled up to 2kw.....

[WBear2GCR]

Ya Mon!

I have this Bird made remote "meter bridge" that shows forward and reflected power, although they don't call it that. 19" rack mount, two meters with a button inbetween, and a meter relay level set (alarm) on the forward meter. Still would like to know what model it is and what it came off?? Schematic would be good.

But anyhow, I was going to simply run it off my SWR bridge's whatchamacallit box and jettison its little meter with the forward reverse switch... before I saw this.

Seems like a better idea to set it up as a fixed forward and reverse reading wattmeter, with maybe a 200 watt/2kw level set switch (or some similar) and make it just drive the meters however they want to see voltage.

The only thing on my mind is some sort of "overpower" shunt for the input of the "reflected" meter - since under normal conditions it would maybe be good to have it read say 200watt max for the 2kw level, or similar... for "fine tuning" of the ant system. But if something went south and the thing reflected big time, I'd not want to fry the chipz. But maybe they wouldn't fry if I simply scaled the output opamp (not shown in the app note) and put a zener shunt on the meter movement (or similar device) to prevent severe over voltage. Hey now, maybe that's a plan??

Anyhow I ordered some...

               _-_-bear

PS. I think I recall reading that the standard "micro match" SWR pick up will not give a true reading of power because of the way it senses forward and reverse RF?? Not sure.