[TenTec] Orion AM RX Performance Measurements

[Sinisa Hristov]

Eric Scace K3NA wrote:
 
>     I wonder what THD looks like for a carrier in CW/SSB
> detection and a bandwidth customary for those two modes.
 
>     I've been running with no hang time and very fast
> dB/s... but maybe I'm tolerating more distortion that I should?
 


A single carrier is not a problem unless it's a very weak
signal and both the noise and the signal trigger AGC action.
This was discussed earlier.

With two or more carriers in the passband, too fast AGC
can create significant intermodulation as the following
measurements show.



Part Five - CW Intermodulation
==============================


Main RX, 3505.15 kHz, LCW
PREAMP OFF, ATTN OFF, RF GAIN 100
ROOF 1 kHz, BW 1000 Hz, PBT 0 Hz

signal frequencies:  3505.00 and 3505.30 kHz
single carrier level = -73 dBm (S9)
measured at speaker output with external 4 Ohm speaker connected
 

Intermodulation Level in dB and Percent below Single Signal


dB/s         IM level
-------------------------
  40      -43 dB =  0.7 %
  60      -40 dB =  1.0 %
  80      -38 dB =  1.3 %
 100      -36 dB =  1.6 %
 200      -31 dB =  2.8 %
 500      -24 dB =  6.3 %
1000      -19 dB = 11   %
1500      -17 dB = 14   %
2000      -16 dB = 16   %



73,

Sinisa  YT1NT, VE3EA