[Elecraft] K3 S Meter behavior

Tom W8JI w8ji at w8ji.com
Thu Jul 15 13:52:29 EDT 2010


> Regardless of the fact that in 1934 (as was indicated to me in off 
> reflector email) we used to not use the meter for the S report, at some 
> time (1970's when proper calibration and standardizations' came about) we 
> were able to shift that OLD antiquated 1934's definition over to a 
> STANDARDIZED S meter reading as part of the RST.


There may be a "standard" some people believe in, but it is a "paper 
standard" that never took hold. Drake used 5 db per S unit as a goal, ICOM 
about the same. Collins was down around 3 dB per S unit as a target.

Most receivers are around 1 dB or so per S unit down around S 1, and very 
few prior to digital processing were ever remotely linear over the S range.

My FT1000MP MKV, sitting in front of me now, is 2 S units per 6 dB at S8 and 
the very same 6 db pad drops it from S5 to S0 (it has that scale point, even 
though there is no such thing).

I've never measured the K3 for many reasons. S meters historically have been 
very poor, absolute signal level at a receiver is not an indication of field 
strength in volts-per-meter, volts-per-meter is not a constant indication of 
S/N ratio or even how "loud" a signal is, and so on. This whole thing is an 
exercise similar to arguing how to measure plate milliamps using #47 light 
bulb.

How would Elecraft or anyone else measure the meaningless S units of an S3 
signal when RF gain is set so the DSP only sees an S5 signal at the lowest 
signal sensitivity? Why work to know what isn't even important, and what is 
never useful?

73 Tom






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