S-meter calibration

[F5LCIjmb]

Hi Elecrafters,
I've been given some old instruments, among them a GR1390-B random  noise  
generator :
     - Maybe it could be of some help for S-meter calibration of my K2?
     - Or for something else in the radio field ?
  72,

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[Ron D'Eau Claire-2]

A GR-1390B is a noise generator. It seems to sell for a few hundred US
dollars on the 'net. Still, I believe it's only good to about 5 MHz, so it's
of limited us with HF gear. Yes, you should be able to use it to 'calibrate'
the S-meter on your K2, as long as you realize that the "calibration",  no
matter how it's done, is very rough indeed! Just do it on 80 or 160 meters.

Set your GR-1390B for 50 uv output and adjust the S-meter MENU settings on
your K2 for S-9.

It's also useful for Spectrogram adjustments, just like the Elecraft N-Gen.

Ron AC7AC

-----Original Message-----
Hi Elecrafters,
I've been given some old instruments, among them a GR1390-B random  noise  
generator :
     - Maybe it could be of some help for S-meter calibration of my K2?
     - Or for something else in the radio field ?
  72,


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[Don Wilhelm-3]

Folks,

I would add to what Ron said that the AGC Threshold setting also has a great
influence on the S-meter.

It is possible to 'twiddle' with the AGC Threshold pot, CAL S Lo and CAL S
Hi settings to obtain most any S-meter reading you want.

CAL S Hi alone can be adjusted to produce the S-9 at 50 uV indication, but
when doing only that, the s-meter range can be constricted or expanded if
the other settings are not correct, resulting in an S-meter that is correct
only at S-9.

I usually adjust the AGC Threshold just below the point where there is no
change between AGC on/off (no antenna connected) - the voltage will be
somewhere between 3.65 and 3.8 volts.

Then set CAL S Lo for no bars showing (RF GAIN set full clockwise and no
antenna connected)

Then set CAL S Hi for last bar lighted with RF GAIN at minimum.

Checks with a 50 uV signal afterwards usually produces an indication of S-9
+/- 1 LED bar for me.  If I want it any closer, I set the AGC Threshold up
or down by a small amount (measure the voltage and move it only a small
voltage at a time - 0.05 volt to 0.1 volt steps only), then re-do the CAL S
Lo and CAL S-Hi - repeat until the desired S-meter readings are obtained.

A bit more involved that the simplified steps in the manual, but then if you
want precise results you have to work at it a bit harder.

73,
Don W3FPR

> -----Original Message-----
> ...
> Set your GR-1390B for 50 uv output and adjust the S-meter MENU settings on
> your K2 for S-9.
>
> It's also useful for Spectrogram adjustments, just like the
> Elecraft N-Gen.
>
> Ron AC7AC
>
> -----Original Message-----
> Hi Elecrafters,
> I've been given some old instruments, among them a GR1390-B
> random  noise
> generator :
>      - Maybe it could be of some help for S-meter calibration of my K2?
>      - Or for something else in the radio field ?
>   72,
>

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