[Elecraft] Chasing the numbers

[Darwin, Keith]

-----Original Message-----
From: Darrell Bellerive [mailto:va7to at yahoo.ca] 

Keith,

I would be interested in reading about your observations on the
differences between receivers. Please consider posting them to the
reflector.

-------------------------

I did my comparisons a few years ago so what follows is my recollection
of my tests.

Omni V vs. 830s.

The TenTec rig had a harsher, more distorted sound on CW and SSB.  It
had a noticeably tighter passband resulting in less splatter and of
frequency noise as well as a more bandwidth limited sound.  My Omni V
with twin Inrad 2.8 KHz filters sounded almost as good as the 830s with
it's stock SSB filters.  The Omni with stock filters was noticeably
narrower than the 830s.  It was clear that part of the 830s' great sound
was the wide receiver passband.  From an AGC point of view, both rigs
were similar with aggressive AGCs with no real slope.


830s vs. K2

This test was done during a CW contest.  The 830s with twin 500 Hz
filters had less selectivity than the K2.  The aggressive flat-top AGC
of the 830s amplified the background noise so it "sounded" S-9.
Consequently, the rig was always screaming at me.  If it wasn't loud
signals, it was loud band noise between the signals.  The K2, with it's
sloping AGC, allowed the background noise to stay in the background.
Overall, the rig was just quieter and cleaner to listen to.  Also, the
K2 receiver did a better job of keeping things clean between stations.
The holes between 2 big stations sounded like holes in the K2.  In the
830s, those holes were filled with garble, grunge, junk.


Drake 2B vs. K2

The Drake is a fabulous sounding rig.  Very clean, smooth, sweet.
Unfortunately, it has a very aggressive AGC so you'll never hear a quiet
band as the AGC ramps up the gain when there is no signal to provide a
constant full-blast noise floor.  Filtering, of course is not nearly as
good as the modern K2, but fidelity and sonic quality is better.  The
wide filtering made strong SSB signals a joy to listen to and CW stuff
came through very clean and pure.  Still, for AGC reasons, I found the
K2 to be more relaxing to listen to in general even though it didn't
sound as good.

I also recorded CW signals and examined their waveform.  The Drake's AGC
was rather slow to kick in so the leading edge of each dot/dash had a
1/2 to 1 cycle spike that was 2x the height of the rest of the signal.
After a cycle, the AGC had caught up and the rest of the waveform was
much more controlled.  Interestingly, this leading edge spike of sorts
did not add any nasty artifacts to the audio.  After seeing it on the
screen, I could hear it in the audio but the little edge at the
beginning was not bothering at all.  The K2, on the other hand had no
such edge and in the headphones did sound a bit smoother than the 2B's
CW tone.


Omni V vs. K1

I had a K1 for a while and compared it to the Omni V.  K1 sounded much
(much) better.  Smooth, pure, nice.  Of course the AGC caused loud
signals to pop and the filtering was not nearly as good, but the K1 sure
sounded nice.  My recollection is that the K1 sounds better than the K2
(less IF noise, for instance) but I never had both rigs at the same time
so I can't say for sure.

- Keith N1AS -
- K2 5411.ssb.100 -
- K3 Wave 3 -