[Elecraft] [K3] IF output

Brett Howard brett at livecomputers.com
Sat Jan 16 01:44:43 EST 2010


Ok so I decided to do the IF mod as the P3 will be ordered when it comes
out and I'd like the increased sensitivity.  I'm copying elecraft and K3
support cause I wanted to ask a simple question (as well as share the
results).  First my question, I didn't have any 13K ohm resistors in
0805 size.  So I put an 0603 resistor on the same pads.  Will this be
ample or should I replace it with an 0805 for power rating reasons?

I made measurements before and after the modification and collected
results which I figured I'd share. 

Signal Generator was a Rhode and Schwartz (sp?) model number unknown.
This signal generator was uncalibrated.  However the spectrum analyzer I
was using was a very recently calibrated N9020A which our cal report
gave a clean bill of health and an absolute accuracy of 0.009dBm at
-50dBm.  Agilent didn't specify the accuracy at -70 but it was getting
tighter as the amplitude went lower.  I did not engage the preamp in the
analyzer.  

I was making my measurements at -70dBm as its a "common ham amplitude".
I injected the signal at 7.040Mhz (cause I use that w/ my XG2 a lot) @
-70dBm.  This input was verified on the spectrum analyzer at the end of
my cable to calibrate cable losses out of the system.  I then measured
the output at the IF OUT port at 8.215Mhz. 

Before
PreAmp off: -88.2dBm
PreAmp on:  -77.0dBm

After
PreAmp off: -77.9dBm
PreAmp on:  -66.9dBm

Looks like there is a tad bit of loss with the PA off (7.9dB) but then
again there is 3.1dB of gain with the PA on...  Hopefully this jives
with intended results.  If not hopefully its a useful data point.

Respectfully

~Brett (KC7OTG)



More information about the Elecraft mailing list