I certainly hope the clicking I hear on the sidetone is an artifact of
the recording process, or something that will go away with the
production version of the K4!
73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
.
On 23/06/2020 12:41, Bob Wilson, N6TV wrote:
Summary: The K4D Receiver Audio and QSK performance seems outstanding --
I'm sold.
I hesitated to order a K4 until I could hear how one sounded in "real
world" pileup conditions, compared to my trusty 11-year old K3s (S/N 1494
and 1495 with KSYN3A upgrades).
Well, here is a short recording I made while operating a K4D Field Test
unit during the All Asian CW Contest this past weekend, so you can have a
listen to the QSK performance and the audio tones when several stations are
calling on about the same frequency all at once, which is the typical
"pileup mush" situation that has been so difficult for most modern radios
to handle (including the K3):
https://www.kkn.net/~n6tv/Pileup_Audio_on_K4D_Field_Test_N6TV.mp3
(Headphones recommended).
With 2 or 3 guys calling, it seemed *so* much easier to pick out callsigns
with the K4D, compared to my K3, especially when they were very close in
frequency, which was often. The audio distortion and "beat note buzzing" I
still occasionally hear on the K3 is not heard on the K4. *This alone is
reason enough for me to order a second K4D* for SO2R contesting.
Note: The "thumps" and clicks you hear in the recording while I'm
transmitting with full QSK are mostly a side effect of the analog recording
method used (rear headphone jack, long cable, ungrounded radio, and
microHAM MK2R+ sound card). I think some RF is still getting into the
MK2R+ despite lots of ferrites. The "thumps" are not heard in the front
panel headphone jack of the K4. The stereo USB Sound in the K4D won't have
these issues.
I also toggled PRE1 and NR (level 4) when a weak one would call, and it
really seemed to help pull them out of the noise. I put both receivers on
the same frequency and used A/B to toggle both settings ON and OFF at the
same time with a single tap (Main RX had PRE OFF and NR OFF, Sub RX had
PRE1 ON and NR ON, and I would swap them). I modified my Win-Test scripts
<https://bit.ly/wtscripts> so I could swap A/B from the keyboard of my
logging program. I've also made scope control work from the Win-Test
keyboard, as with my P3 scripts. The radio responds to CAT commands
instantly, as does the touch screen display.
Unlike the K3, I could keep the RF Gain at MAX and hear no real problem
until the bands got really noisy, then backing it off helped a bit, as did
the attenuator. But I like the way the fast AGC worked. Loud stations
never hammered my ears, and there's a new "AGC attack time" setting that we
don't have in the K3 that will require further experimentation.
As for QSK, I went back and forth between QSK ON and QSK OFF, Delay 0.00.
There's a huge difference. QSK OFF Delay 0.00 is much quieter, but I like
to hear more between elements.
QSK performance was *way* better than the K3, especially at high speed (I
went up to 39 WPM). Amp. is a KPA1500. No CW jitter was observed, so "CW
QRQ" mode is no longer needed to send clean CW at high speed with either
internal or external keying. I used 5 ms of keying compensation and got
good reports from that, but I need to get out my scope and make some
measurements.
I figured I would eventually want to order the K4 "HD" model, but I may not
need it. So far the receiver performance seems really good, even when
getting close to loud signals. But I don't have a way to make the careful
receiver performance measurements that Rob Sherwood, NC0B, can make.
The band scope has much finer resolution than the P3 or an IC-7851, but I
still need to experiment with an external HDMI monitor, which will provide
even more pixels for the band scope.
Physically, a K4D is smaller than the K3/P3 combo. side by side, and it's
only about 3/4" taller and maybe an inch deeper.
The K4 buttons have a very nice tactile feel, much improved over the K3.
Every knob except AF Gain seems to be an optical encoder rather than a pot,
which means there is potential to control just about everything from your
logging program keyboard, without having to touch the radio.
The "tap to tune" feature of the waterfall display seems to work well for
making big frequency movements. I need to try it with a USB mouse. Better
than that, there's a new method to automatically adjust the band noise
level on the scope so you don't have to constantly fiddle with a "REF LVL"
setting as we do on the P3.
There's more to write, but this post is long enough already.
In sum, I know we've all been waiting a long time for the K4 to be
delivered. I think it will be well worth the wait, and that your patience
will be rewarded. Meanwhile, me and my fellow volunteer Field Testers will
be very busy trying to find all the bugs so that you won't have to. :-)
But as delivered to us, it seems very stable, and very usable. Most of the
major features are working quite well at this point.
73,
Bob, N6TV
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