Ron and all,
Here's my findings for my Orion II. I notice that your meter
is more generous by 10 to 13 dB!
This table shows the input power needed to obtain the
following Orion II S-Meter readings using an Agilent 8648B
RF frequency generator.
Frequency = 14.1 MHz
PreAmp was found to have 10-11 dB gain.
Meter Preamp On Spot check
Reading Input Level with preamp off
(S-Units) (dBm) (uV) (dBm) (uV)
0 -111 0.63(to just move needle)
1 -106 1.12
2 -103 1.58
3 -100 2.24
4 -97 3.16
5 -94 4.46
6 -91 6.30
7 -88 8.90
8 -84 14.1
9 -80 22.4 -70 70.7
+10 -74 44.4
+20 -69 79.3 -59 251
+30 -62 178
+40 -54 446
+50 -46 1120
+60 -36 3540 (-7 99900 w/ 18dB atten!)
Just a note about S-Meters. From what I've read it was only
ever intended as a relative signal strength indication,
meaning that from one receiver type to the next, there is no
correlation. It looks like rig vendors are at least starting
to calibrate them at one point, S9/50uV. Traditionally, the
actual measurement was of the AGC voltage. How this voltage
tracks signal input level is completely dependent on the
gain control characteristics of the rf/if amplifiers
involved, so it is highly variable. So I don't believe it
makes sense to say that +10 over S9 means 10dB over S9, etc.
But now that we have software running our s-meters, it is
possible to display a calibrated signal level measurement,
taking preamps and attenuation into account, with the scale
in dBm or dBuV, rather than S units. Unfortunately, I don't
think this would be an easy thing for manufactures to
do. Each rig would need to be calibrated independently,
given the component variations from unit to unit.
... ramblings from this engineer :)
73,
Lin
WB1AIW
-----------------------------------------------------------
Ron Castro wrote:
> Whoops...I didn't mean for it to come out like that! Lets try this...
>
Reformatted:
Orion II S-Meter Readings from Ron Castro, N6AHA
from E-mail rcvd February 18, 2006
Standard Standard Orion II Pre off Orion II Pre on
S-Units uV dBm pre off Descrep Pre on Descrep
S-5 3.16 -97 S-2 -12 dB S-6 6 dB
S-7 12.57 -85 S-5 -12 dB S-9 12 dB
S-9 50 -73 +5 5 dB +30 30 dB
+10 158 -63 +25 15 dB +42 32 dB
+20 500 -53 +40 20 dB +55 35 dB
+30 1583 -43 +52 22 dB +60 30 dB
+40 5006 -33 +62 22 dB Off Scale N/A
+50 15830 -23 Off Scale N/A Off Scale N/A
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