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KD8CEC 1.2 S meter movement, but no sensor!


 

Hi,

Trying to get a working s sensor for KD8CEC.?I enabled the analog (A7) S sensor and then turned it on in the ubitx database manager. ?I breadboarded one based on a blog post by KD8CEC. Although there is some weirdness (on background noise only, see the sensor level steadily increase to s9), decided to solder it up and see if playing with the capacitor will get a reasonable set of responses.

So here the sensor is completely disconnected, but S meter still enabled in the software. And to my surprise, I start seeing what almost looks like reasonable strength readings. Fired up the Ubitx Database manager again, put it in simulation mode, and the bits read from A7 seem to vary between 20 and 200, generally with the strength of signal. I do have the "front panel board" supplied with my case from???but as far as I can tell, the A7 pin is disconnected.

My guess is that I am just seeing the impact of noise on the "floating" input. ?Any other thoughts?

73
Mark
AJ6CU


 

I remember seeing that, too. If memory serves, use those for your min/max values when setting smeter break points in the mem manager. With the meter installed, you should get a fairy stable number based on the freq. I think it took a bit of time to get the break points in the ball park. I'm on a full agc on one rig and the stand alone analyzer on the other...so, I can't check for you.


 

Definitely sounds like your just getting leakage/pickup on that pin. The inputs are considered "High impedance" and will only drain slowly so if there is a lot of energy floating around (and its a ubitx we know there is!) it will definitely pick up some of that and store it in what little capacitance the wires provide. The fact that is is consistent is amusing at least :)

-- Tim Keller - KE2GKB