[Elecraft] P3 display...

[Scott Ellington]

The K3 IF output to the P3 comes from the Post-amp following the first mixer, ahead of the crystal filters.  The only upstream filters are the broad bandpass filters, each of which covers an entire band.  In addition, the K3 applies no AGC to the stages ahead of the IF output, which makes possible the P3 absolute amplitude calibration.  It's also the reason the P3 has a relay-controlled amplifier, which you will hear switching out whenever really strong signals appear on the band.  This keeps the ADC in the P3 from saturating.

73,

Scott  K9MA


On Feb 23, 2011, at 12:37 PM, Bill K9YEQ wrote:

> 
> Notice that changing the filters does nothing to the display.  So the
> signal sample is ahead of them.
> 
> Bill
> K9YEQ
> 
> 
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Phil Hystad
> Sent: Wednesday, February 23, 2011 11:57 AM
> To: elecraft at mailman.qth.net
> Subject: [Elecraft] P3 display...
> 
> I have a question about the P3 -- the cursor width shows the filter width.
> But the P3 shows signals outside of the filter bandwidth.  This must mean
> that the sample of the IF signal is before the roofing filters.  If that is
> the case then I am assuming that the signal within the frame of the cursor
> is not a signal that has passed through my roofing filters.
> 
> Is this a correct interpretation?
> 
> 73, phil, K7PEH
> 

Scott Ellington
Madison, Wisconsin
USA