Posted by
wayne burdick on
Sep 20, 2011; 5:33pm
URL: http://elecraft.85.s1.nabble.com/K3-test-w-o-w-I7SWX-2T-FSA3157-H-Mode-Mixer-tp6812860p6813125.html
Hi Sergio,
Thanks for reporting these interesting results.
A few K3 users in extremely high-signal environments might benefit
from a few extra dB of dynamic range, at the cost of a mixer add-on
module like you described.
However, I'd be concerned about the possibility of additional mixer
spurs. Switching mixers put out a large number of VHF/UHF spurs that
can mix with harmonics of other signal sources (primarily the VFO) to
produce HF-6 meter spurs. This is an inherent issue with high-level
superhet receiver designs.
Our first mixer design trades about 1 dB of dynamic range and
conversion loss for excellent rejection of mixer products above 60 MHz
by integrating a balanced low-pass filter into the commutating path.
Without this, there would be a "picket fence" of additional VHF/UHF
products and thus many more spurs.
Please let me know if you do a comparison test of the two mixers in
this regard. The best way to do it is to slowly sweep through each ham
band in CW mode using a narrow crystal filter.
73,
Wayne
N6KR
On Sep 20, 2011, at 9:16 AM, ik8tng wrote:
> The *Elecraft K3 *is one of the best performance commercial
> transceivers
> available to amateur radio operators.
> While discussing with some friends it's receiver performances we
> decided to
> see if there were chances to improve it. When a receiver has a
> dynamic
> range over 90dB it is not so easy to pull-out additional dBs.
> One easier mod to experiment was the replacement of the 1st mixer....
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