Topband: BDR redux

Jim Jarvis jimjarvis at comcast.net
Thu Feb 5 17:03:58 EST 2004


Ok, Ok...

dB = 20 log (v2/v1)  

It was early...not enough caffeine, and I swagged instead
of calculating.  To make matters worse, at some point I 
switched from dBm to dBv.  DUH.  

Thanks to all who reminded me that I shouldn't do that.
(and now you know why I'm in marketing...far too intuitive!)

Filter that noise out, and the point still holds...we're
believing meters that are displaying nonsense, and it's
contributing to what appear to be wide variations between
lab and field observations.  

The real dynamic range of signals is less than we perceive,
and the performance of 'good' radios only roughly relates 
to tests which report IMD and BDR, even at 5KHz.  

I had one guy assert that s9 was 50uV in 50 ohms, because 
that's what Kenwood says.  Another said 100uV, because that's 
what ICOM and Yaesu have said.  What does TenTec say?

Does the Orion happen to have its relative AGC indicator 
calibrated in dBm?     

Jim N2EA
jimjarvis at ieee.org 



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