[50mhz] [VHF] Preamp and receiver question

[n6gn at sonic.net]

 33 uV vs 3.3 uV is a voltage ratio of 10 but a power ratio of 100. Thus
even for the same
 S meter's there could easily be 6-8 S units of difference. 
 A 706mkIIg should be factory calibrated at the noise floor, S9 and (if I
remember
 right) S9+20.  In between it does what it does and the 6M preamp is no
doubt 
 different from the HF preamp (is on mine anyway) but mine tends toward
around
 3 dB/S unit for the first few and then gets somewhat more conservative. I
think that
 S9 to S9+20 is about 20 dB - though it's a bit hard to read with the
bar-meter.

 There may be no real difference in the ability hear signals between the
706 and 450 
 given your environment.

 Glenn n6gn

  very different. For the 706 with the preamp on on 6 meters, a S9 signal
 takes 3.3 microvolts, which is insanely liberal, but that is what it is.
 For the FT450 under same conditions (preamp on, 6 meters) it takes a 33
 microvolt signal for S9. That is a factor of 10, which should show up as a
 10db difference on the meter-correct? If that is correct, we have a 13db
 difference in readings between the 706 and 450 (3 db for increased MDS,
10db
 for the meter difference). That should be 2 S units or maybe 3-4 given the
 non linear calibration of most meters. But I am seeing a 7 S unit
 difference or so.