Re: [amsat-bb] For those with TS2000's - calibrated S-Meters

[K5OE@xxxxxxx]

Alan,
Thanks for the testing and the informative, detailed report.  I have done a little "playing around" with the S2 beacon while AO40Rcv is up and running, and find about the optimum IF DSP settings for getting good blocks to be Lo=200-400 and Hi=1800-2000:  about a 1600 Hz to 1800 Hz bandpass.  It seems to be a little sensitive on the low side, but you have to get below 1600 Hz on the Hi side before it starts consistantly dropping good CRCs.  I use no RX AF DSP.
73,
Jerry, K5OE

In a message dated Tue, 22 May 2001 11:46:36 AM Eastern Daylight Time, "Adamson, Alan" <Alan.Adamson@BellSouth.com> writes:

<< All,

I hooked up the HP8920A to my TS2000 and calibrated it's S-Meter... Actually I have two of them... a regular 2000 and a 2000X that I just picked up at Dayton.

Here was the results of both the S-Meter and the RX NF (the S-Meter test was done with a 1khz tone in SSB and the filters set to 300/2400, freq on this test was 433.350).  This is not a sensitivity test... I'll give you that below.  I'll try to do a 145mhz test as well to see if anything changes.

S-Meter
Nothing on the meter (next increment of signal will give an S0 reading)
-116dBm
S0
-115dBm
S1
-113dBm
S3
-110dBm
S5
-107dBm
S7
-102dBm
S9
-93dBm

I also did a NF test... I generated a 1khz tone with the filters as set above.  For a 10db SN, I got the following
-130dBm

so do the math.
-130-10=-140 (the 10 comes from the 10db SN
-140-30=-170 (the 30 comes from 10*log(1000))
-170+174=4.  I'd say that is a +-1 value.

So for the 2000, looks like a  5 for the NF and a bandwidth of 2100.  One note, I cranked in the cw filters and shut it down to 50hz (yes you can do that on the 2000).  Needless to say, I couldn't generate a low enough signal to test this and I didn't have an external attenuator.  My HP only goes down to -136dBm and I still had too much SN in this setting :-/.  One final note, the 2000 uses IF DSP and it may artificially effect the NF to the good.... Either way, that little sucker is pretty impressive.... assuming I did the tests right :).

Alan

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