Ron,
At 04:01 11-05-05 -0400, you wrote:
You can't get an idea of the absolute sensitivity of your K2 looking at the
S-meter, Mike.
[SNIP]
Look up "Receiver Sensitivity Testing" (Page 4 of the XG1 manual) and
"Signal-to-Noise and MDS Calculations (page 5) for instructions on how to
use the XG1 to measure receiver sensitivity.
I did, and found this procedure and example:
A. Divide S+N by N; call the resulting ratio R.
B. Take the base-10 logarithm of R ("log" key on most calculators).
C. Multiply the result by 20 to obtain the S+N/N ratio at 1 microvolt, in dB.
D. If the S+N/N is greater than 10 dB, then the MDS is approximately
equal to the result from (C) subtracted from -107 dBm.
Example: DMM readings of 1.0 Vrms (XG1 on), and 0.030 Vrms (XG1 off).
A. R = 1.0/.03 = 33
B. log(30) = 1.52
C. 20 x 1.48 = about 30 dB (this meets the requirement for step D)
D. MDS = -107 dBm - 30 dB = -137 dBm
Two remarks:
1. I think the second step in the example should read: "B. log(10) = 1.52".
2. I may be missing something here, but if the outcome of B) equals 1.52,
why is "1.48" used in C)? (Not that it changes much, only 0.8 dB, but hey:
it might confuse some people!)
Best, BartW de PA3GYU
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