Re: ND6T AGC S Meter Calibration
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The s-meter wire goes to the? pin at the hot end of C4? where the pins are.
Here is what I got, don't recall the frequency.?? .4 volts for 50 uV or -73 dbm 4 volts -40 dbm 3.9 volts -50 dbm 1.8 V -60 .55 V -70 .1 V -80
Using the following in the manager. 4,36,71,106,140,175,212,217
50 uV shows 3 bars on the meter -63 dbm shows 6 bars -57 dbm shows? + -51? dbm shows ++
I was using an IFR 1200s and Fluke digital multimeter.? The s-meter pin was disconnected when doing the voltage measurments.
de ku4pt
On Mon, Jul 23, 2018 at 7:54 PM, Mark M <junquemaile@...> wrote: I have Don's & Kees' AGC board in my uBitX and am trying to get the S meter function in Ian's firmware working. I've been using the S meter helper in the Manager to try to set some meaningful values but have not been terribly successful so far. It seems like only the strongest signals give a usable level, it shows either a very small value or about a 75 value with little variation in between, it's either S1 or S9+ with nothing in between.
I borrowed an Elecraft XG2 receiver test oscillator from a friend to try the calibration with known input levels (it puts out 1uV and 50uV signals on 80, 40, and 20M). Measuring the voltage on the AGC board at J1 I get the following (I hope this is readable):
Band? ?No Sig? ? 1uV? ? 50uV
?80? ? ? .4mV? ? ?1mV? ? 1.6V
?40? ? ? .3mV? ? ?.5mV? ?1.7V
?20? ? ? .3mV? ? ?.7mV? ?1.6V
Are these values typical? I'm not 100% sure the board is working correctly anyway...it's my first attempt at surface mount assembly so I may have messed up something altho I don't see any obvious problems. The radio seems to work just fine otherwise and the receiver seems to have decent sensitivity, to my ear at least.
The S meter is certainly not essential but since it's there, I'd like to see if I can get it working.
Anyway, any advice/opinions/comments are appreciated.
Mark? ? ?AA7TA
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