[Elecraft] P3 Cal Question

[Alan Bloom]

Fred,

It could be that the IF output mod was never done on your K3.  I'm
pretty sure S/N 642 was before the change was made in production.

http://www.elecraft.com/K3/mods/IF_Output_Buffer_Gain_Mod_Rev_A.pdf

Another possibility:  Were you using a CW or a modulated signal for
calibration?  Modulation spreads the signal out over several pixels of
the P3 screen, making it look lower in amplitude than on the K3 S-meter,
which measures the complete signal within its filter bandwidth.

Another possibility:  If the K3's CONFIG:SMTR MD is set to NOR (normal)
then the K3 S meter reading is affected by the on/off state of its
preamplifier and attenuator, which does not affect the P3 reading.

Both of those last two issues are explained in the "How to Set Up and
Interpret the P3 Display" section of the P3 manual, under "Spectrum
Display".

Alan


On Sat, 2012-03-24 at 13:57 -0700, Fred Jensen wrote:
> I decided to do a K3 S-meter and P3 Lvl Cal, using my service monitor. 
> Everything seems to be OK, the P3 comes much closer to the S-meter now, 
> but the P3 Lvl Cal [transfer gain?] came out at -23.7 ... it was -7.6 
> when I put it together.  I'm sure the difference between the P3 and 
> S-meter is just averaging, with the service mon it is right on -73 dBm 
> for 50 uV.  Is -23 normal?  K3 S/N = 642, it's been in Aptos two years 
> ago however.
> 
> 73,
> 
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 2012 Cal QSO Party 6-7 Oct 2012
> - www.cqp.org
> 
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