[Elecraft] [K3] K3 S Meter

[Don Wilhelm]

Bill,

If the K3 S-meter is calibrated with the  preamp ON, and then ABS mode 
is set on, the S-meter response for a 50 uV input will be S-7.
If one is going to use S-meter ABS, then it is best to calibrate the 
S-meter  for S-9with the preamp off.

Yes, I know what "the manufacturer's instructions" say, but I know how 
my K3 responds, and I also recall Lyle Johnson's response to this exact 
situation in his posting of November 15, 2009 in which he said the 
S-meter must be calibrated for the way you will use it.  He in fact 
calibrates his with the PREAMP and ATTN both OFF and uses the S-meter in 
ABS mode (just as I do).  When calibrated that way, it will not be 
correct in NORMAL mode if the preamp is ON.

In other words, the S-meter will respond correctly only under the 
conditions for which you calibrated it.  You get to decide what your 
normal operating situation will be - S-meter normal or absolute, preamp 
on or off and attenuator on or off.  I prefer to use S-meter absolute so 
S-9 indicates 50 uV at the antenna input regardless of whether the 
preamp or attenuator is on or off.  Take your pick.

Yes, I believe the manual could be more explicit.
73,
Don W3FPR

Bill W4ZV wrote:
> On Wed, Nov 18, 2009 at 12:09 AM, Philippe Trottet [via Elecraft] <
> ml-node+4023431-500668120 at n2.nabble.com<ml-node%2B4023431-500668120 at n2.nabble.com>
>   
>> 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
>>
>>     
>
> Bon jour Phillipe,
>
> The simple answer is "Always follow the manufacturer's directions".  A more
> complex one is that the K3, being a DSP rig, compensates internally in
> firmware for the fact that PREamp is ON during the calibration procedure.
>
> I also recommend using CONFIG: SMTR MD - ABS.  This will place the K3's
> S-meter in ABSolute mode, so that the S-meter always reads the signal being
> applied to the input terminals correctly, independently of whether PRE or
> ATT are selected internally.  This is also different than most rigs but, if
> you think about it, it is better since the S-meter always read the true
> signal level at the input terminal, before any gain or attenuation is
> applied inside.
>
> 73,  Bill  W4ZV
>
>   
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