[Orion] Orion S-Meter Test Results

[Bill Tippett <btippett@alum.mit.edu>]

        Thank you for making those measurements Jim!  I've wondered
about the S-meter readings myself since I used a FT-1000MP for 6.5
years and made about 40k QSO's in various 10 meter contests.  Orion's
meter seemed stingy compared to the MP's, especially below S9, but
full preamplification in both cases.  The MP uses an additional "Tuned"
mode preamp on 10/12 meters so that may explain the difference.

        Just for my own curiosity, I converted your measurements below
S9 to dB relative to S9:

S-Meter Actual Signal
        S1              S9 - 44.4 dB
        S3              S9 - 30.5 dB
        S5              S9 - 20 dB
        S7              S9 - 11.7 dB
        S9              50 uV
        S9+10           S9 + 8 dB
        S9+20           S9 + 18 dB
        S9+30           S9 + 29 dB
        S9+40           S9 + 42 dB

Assuming the typical 5 dB per S-unit, the meter looks more linear
than most especially below S9.

        Regarding the Antenna Port Isolation, you wrote:

Also, I measured the isolation between the two antenna ports. On 10m, the
isolation was 40 db, and it increased to 45 db on 160 m. This is
acceptable, but not impressive isolation. It means that an S9+40db signal
on one antenna will still read S9 if the other antenna port is
selected.  Normally, this would not be a problem.

        This is a bit of a concern to me.  I first noticed it when reading 
ARRL's
report showing similar data (page 15).  They measured 42.3 dB isolation
when ANT 1 is selected and ANT 2 is unselected.  When swapping ports, they
measured 51.4 dB.  I've actually noticed this on the air and have even gone
to the trouble to put a 50 ohm attenuator on my unused antenna port.  I 
haven't
tried Diversity receive on Orion yet, but am wondering if my vertical on ANT 1
and a dipole on ANT 2 would cause any problems due to isolation?

        Could you also measure the isolation between the AUX RX port and 
ANT 1
or ANT 2?  This is actually of more concern because I don't want my noisy TX
antenna (vertical) adding noise to my Beverages feeding AUX RX.

        Thanks for publishing your measurements...very useful info!

                                                        73,  Bill  W4ZV



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