I just built an Elecraft XG-2 test generator. For those
who don't know the model, it's a high accuracy
(output level -107dbm +/-1db) 80/40/20 meter RF
generator. I've used it in the past to determine the
Minimum Discernable Signal or noise floor of a reciever.
Here are some of the past results I've gotten:
Elecraft K2 #4913 -143dbm
Kenwood TS-850SAT -136dbm
Yaesu FT-920 -137dbm
Now to the good stuff - my recently aquired TR4:
20m: -147dbm
40m: -152dbm
80m: -151dbm
To measure this I injected the generator's -107dbm
(1 microvolt) signal and measured it's peak then
measured the noise next to the carrier and did a
little math. I also measured the same spot with the
generator on and off.
My numbers might be off because I could not turn
off my AGC but to correct for this I made measurements
at many differant "RCVR GAIN" settings on the TR-4 and
averaged them out. I found that with the gain set to
anything less than 11 o'clock, there was no AGC action.
I used "Rocky", a SDR program that shows the spectrum
around a signal like a pan adapter. I also ran the tests
witn "Spectrogram", a spectrum analyzer and got very
close to the same numbers. Another impression is by
my ears - the -107dbm signal seemed to be easiest to
pick out of the noise on the TR4 than the other rigs.
BTW the 50 microvolt setting produced a S9 signal
on all three bands.
The main reason I wanted to test the MDS of my TR4
is the fact that the reciever is sooooo quiet that I got
the impression that it was deaf or broken.....
Deaf? NOT!
I've only been a Drake owner for 5 days but I'm quickly
becoming a fan!
73's de Ken KG0WX - Kadiddlehopper #11808, Flying Pigs #-1055, Grid
EM17io
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