Travis,
I doubt the RX gain calibration will make that much difference, but
rather I suggest that some alteration of the AGC parameters will make
the most difference for you. Take a look at the "Noisy K3" article on
my website www.w3fpr.com for some guidance in adjusting your settings.
That article was written before the AGC parameters were expanded, so you
will have to experiment a bit, but the article should give you some
guidance on which direction to go.
Turning the preamp off and even turning the attenuator on for lower
bands where the band noise is higher will make a great difference too.
If you can hear an increase in band noise when the antenna is connected,
you have ample gain - turn off the preamp and try connecting the antenna
again - if there is still a substantial increase, try turning on the
attenuator. You are not going to be able to copy signals below the
noise level, so you don't need the added gain - it just makes everything
(including the noise) sound louder.
73,
Don W3FPR
On 3/18/2013 8:24 AM, Travis Brown wrote:
All,
I put together a K3 kit about 6 weeks ago. Wow, that was an amazing
project. Many thanks to Elecraft for making that option available. The
problem I am having is that on 180/80/75/40 and sometimes 20, the noise
floor is about S7-9. It is about the same on both my antennas (OCF dipole
and 43' vertical) with the OCF being a smidge quieter. My first thought
was that I had some local noise and asked my dad to bring over is KX3 so I
could walk around the house to find the source of the noise. I did find
that the power supply in the iMac is ridiculously noisy, but that wasn't
getting into my signal, especially since my antennas are almost 100' from
the house. What I DID notice was that when I plugged my antennas into the
KX3, the noise floor was at S0 on 20/40 and around S1 or S2 on 75/80/180
with the pre-amp off. That was MUCH better. Of course, if I fiddle with
the RX gain knob, I can make the noise go away, but it does mess with the
S-Meter and it becomes increasingly useless. So, my thought was that since
my dad had his KX3 factory built, they did a proper RX Gain calibration.
Since I didn't have a calibrated signal generator, I just used the factory
defaults which maybe aren't so great? My question is this: would it make
sense to seek out a calibrated RF source and try and run a proper RX Gain
calibration? Would it likely solve my problem?
Thanks,
Travis
K2NP
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