[Elecraft] K3 S Meter

[Oliver Johns]

Hi Philippe,

I think that instruction is in error.  I adjusted mine with both the  
preamp and the attenuator OFF.  Makes more sense that way.  Turn  
CONFIG: SMTR MODE  to nor.  Turn preamp and attenuator OFF, and then  
adjust your S meter.  Now if you decide to turn SMTR MODE to ABS,  
you'll find that it is already adjusted correctly and does not require  
re-adjustment.  Evidently, the current firmware has the ABS mode track  
the nor mode with both preamp and atteunator off.  Perhaps there was a  
change in the firmware at some point in time that did not get  
reflected in the Operators Manual.

73,

Oliver Johns
W6ODJ


On 17 Nov 2009, at 21:08, Philippe Trottet wrote:

> Dears
> I've seen on the manual S9 /50 microvolts is adjusted with Preamp ON .
> As a new Elecrafter I need some explanations, because with my  
> previous rigs, I use to calibrate S9 without the preamp.
> Thanks
> Philippe A65BI
> K3 #3616
>
>
>
>>>> Bill W4ZV <btippett at alum.mit.edu> 17-11-2009 22:25 >>>
>
>
>
> Geoffrey Downs-2 wrote:
>>
>> A couple of years ago there was some correspondence on the  
>> reflector about
>> whether an S unit is 6db or 4 db and there appears to be historical
>> precedent for both but I have looked at the archive and can't find  
>> where
>> it
>> rested as far as the K3 is concerned. It occurred to me while  
>> recently
>> re-calibrating my S meter with the XG2 that if, in accordance with  
>> the
>> manual, you set S9 to be 50 microvolts and adopt 6 db per S unit the
>> reading
>> for 1 microvolt should be between S3 and S4 (S3 being 0.78  
>> microvolts and
>> S4
>> 1.56 microvolts by my calculations). For practical purposes S3 is  
>> probably
>> close enough rather than "about S2 or 3" as shown in the manual. Or  
>> is it
>> more complicated than that? My arithmetic is not up working out how  
>> many S
>> units one microvolt would be at 4db per S unit but I suspect it  
>> would be
>> further away from S2 or 3. Anyone care to comment?
>>
>
> I believe 6 dB is the "correct" definition, but most S-meters (K3  
> and Flex
> 5k excluded) are very non-linear at low S-meter readings.  IMHO the
> following is an accurate summary of what readings should be:
>
> http://www.n6rk.com/S_unit_definitions.doc
>
> I would adjust the K3 for the XG2's 1 uV output to solidly display  
> S3 (i.e.
> no flicker of S2-3).  That would only be 2.16 dB off (20 log .78/1),  
> which
> is probably "close enough".
>
> 73,  Bill
> -- 
> View this message in context: http://n2.nabble.com/Re-K3-S-Meter-tp4019422p4020331.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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