[Orion] S meter

[Martin Ewing]

The discussion about S meter calibration reminds me of a question I have for all 
the grey beards out there.

If S9 = 50 uV is standard, and 6 dB per S unit (or is it 5 dB?), my question is 
what is the "reference plane" for the measurement?

The useful reference, to me, should be the input connector.  If that were true, 
the S meter reading should NOT CHANGE when switching the preamp on or off or 
changing the attenuator.  This is clearly not the case with the Orion - or with 
many (all?) rigs I've used.

Except for history, we would be better served by power measurements -- "Your 
sigs today are -120 dBm, old man".  Or maybe, "Your sig is 10 dB above my noise 
level."

Accurate S readings (or power for that matter) aren't very meaningful if you 
don't know the antenna/feed line gain/loss.   Frequently I am getting 589 or 599 
when my Orion's meter shows S4 for the other guy.

Oh well, it's a hobby!

73, Martin AA6E

p.s. Nice S meter stuff at http://www.geocities.com/ja1vbn2000/etc/S-unit.html