[Elecraft] KX3 as a base station? Yes, because it's all relative

Sun Aug 5 12:23:39 EDT 2012

Hi, List,

I got my hands on a friends KX3 yesterday when he brought it over to my
shack. I have one on order (Dayton order, September/October, I hope) but my
friend ordered his in February and it landed last week. We played with it
for over an hour, and after I found a PL-259 to BNC adapter, I was very
impressed. Antenna is a 6BTV mounted on the ground with 30+ radials,
excellent low takeoff vertical.

As you may know, the NA CW contest was on and the bands were crowded. In a
direct (subjective) comparison with a FlexRadio 5000, the noise level was
lower with the KX3. Out of passband signal rejection seemed lower and the
front end artifacts that the Flex hears (as hiss) from very strong stations
was non-existent. Although the antenna in use gives good SWR in the bands
we tried, the antenna tuner was very quick to return 1.1 - 1 swr in the low
ends of 20m and 15m. I love the display!

The two loudest complaints I've read on this list:
1. The Knob tightness - the knob WAS tight, but it was a positive, smooth
turning feel and there was no "flywheel" effect - you couldn't spin it and
watch the frequency move. A knob tightness adjustment like on the IC-7000
could be comparable if it were adjusted tight. My observation is that it is
No Big Deal. Will it get looser over time? I hope not much looser!
2. The speaker rattling: Yes. If you turn AF gain way up, the speaker will
rattle. If you turn the audio gain up on my entertainment receiver in the
shack, I can make the windows rattle, too. ("Doctor, Doctor, it hurts when
I do THIS." Doctor: "Don't do THAT.") So it won't get really loud without
distortion. Again, No Big Deal, surgery is not required, IMO, you can hear
the radio quite fine and clear at a lower audio level (in the shack with
the AC running.)

Thanks for all of your postings, they're very informative, and thanks to
NQ2U who brought over KX3 # 0960 for a great introduction to a great radio.
I can't wait to get mine!

73,

Mickey N4MB

On Sun, Aug 5, 2012 at 10:47 AM, Joe Subich, W4TV <lists at subich.com> wrote:

>
>  > Does "home station" actually imply a fixed set of requirements?
>
> No, but one would expect the minimum standard to include such things
> as (separate) fixed level input and output for digital mode interfacing
> particularly if the transceiver supports digital modes otherwise.
>
>  > True, there's no separate line in/out. We will, however, be adding
>  > separate gain controls for data modes.
>
> While separate gain controls are nice, separate I/O should be a given
> in a home station rig to avoid the need to plug/unplug cables - or the
> need to build an outboard audio management device just to switch modes.
> Even the low power IC-703 and FT-817 provide separate Line In/Line Out
> connections and they've been around for what, 10 years?  Other than the
> K2 and Flex radios, I haven't seen a transceiver without separate Line
> in/Line Out connections since the FT-840 (20 years?) except in some
> CW only trail radios.
>
> > I also differ on some of your comments on the KX3's audio. There is
> > no "lack" of a headphone amplifier. The KX3 has a headphone amp that
> > is quite capable of driving any type of headphones to more volume
> > than you need, at low distortion.
>
> Perhaps I was given incorrect information by someone at Elecraft.  What
> I received indicated that the headphones were being driven directly by
> the DAC which had limited drive capability which might be a problem
> particularly with inefficient, low impedance headphones.
>
> I won't even repeat the issues with the speaker.
>
> > The KX3's phase noise was recently tested a well-known third-party
> > test organization. They measured -142 dBc/Hz at a 2.5 kHz spacing,
> > and -145 dBc/Hz at a 20 kHz spacing. The noise was still going down
> > monotonically all the way to 500 kHz (their last data point). This is
> > better than almost all "home station" transceivers.
>
> That's is good to know - congratulations.  How will that translate to
> composite transmit noise spectrum?  I would absolutely hate to see a
> low power radio with "home station features" be used with 100/1500W
> amps and turn into a wideband noise generator like my neighbor's IC-746.
>   I realize the requirements for spectral purity are lower for
> low power transceivers they should still be "good neighbors" when they
> are used with amplifiers in a "home station" configuration - many of
> the low power radio/inexpensive amplifier combinations are anything
> but good neighbors.
>
> 73,
>
>     ... Joe, W4TV
>
>
> On 8/4/2012 3:56 PM, Wayne Burdick wrote:
> > Joe Subich, W4TV wrote:
> >
> >> If Elecraft are marketing the KX3 as anything other than a trail radio
> >> the design missed the mark by 5 km.  ... lack of headphone amplifier,
> >> and lack of separate line in and line out
> >> audio connections, the rig is severely lacking is the "home station"
> >> department - particularly for digital (RTTY/PSK/JT65/etc.) operation.
> >
> > Joe,
> >
> > Does "home station" actually imply a fixed set of requirements? Prior to
> > starting Elecraft with Eric, my entire home station was a Wilderness
> > Radio Sierra transceiver (one of my earlier designs). I was quite happy
> > to change bands with modules, log with a pencil, match antennas with a
> > manual tuner, and key the rig with a homebrew keyer based on a Curtis
> > keyer chip.
> >
> > Surely the KX3, with all-mode/all-band coverage, full I.F. DSP, dual
> > watch, a generous user interface, attached keyer paddle, battery pack,
> > ATU, roofing filters, and full remote-control command set, could be
> > considered a home station -- at least for some operators.
> >
> > I also differ on some of your comments on the KX3's audio. There is no
> > "lack" of a headphone amplifier. The KX3 has a headphone amp that is
> > quite capable of driving any type of headphones to more volume than you
> > need, at low distortion. This same jack can drive virtually any type of
> > powered external speakers. Since the KX3 excels at stereo audio effects,
> > including dual watch, I would think most operators would want to use
> > dual external speakers anyway. Yes, the internal speaker is small, but
> > it was never intended as the primary transducer.
> >
> > True, there's no separate line in/out. We will, however, be adding
> > separate gain controls for data modes.
> >
> > Once we add the 100-W companion amp, the distinction between the KX3 and
> > a much larger "home" transceiver will be further blurred.
> >
> >
> >> ....with a SIS-570 based local oscillator and direct conversion
> >> the jury is still out as to whether the phase noise/reciprocal mixing
> >> performance is sufficient for use in strong signal (receive) and high
> >> power (> 10W) transmit environments.  Unless SiS have improved their
> >> products greatly or Wayne has some magic in his implementation, I am
> >> very concerned (witness the phase noise in the XG3).
> >
> > Actually, the jury is in :)
> >
> > The XG3--a very small device--uses a CS-2100 to keep cost and current
> > drain low. It has a noise floor of about -105 dBc/Hz at all offsets.
> > This is appropriate for a simple RF generator.
> >
> > The KX3's phase noise was recently tested a well-known third-party test
> > organization. They measured -142 dBc/Hz at a 2.5 kHz spacing, and -145
> > dBc/Hz at a 20 kHz spacing. The noise was still going down monotonically
> > all the way to 500 kHz (their last data point). This is better than
> > almost all "home station" transceivers.
> >
> > So phase noise is not an issue.
> >
> > Of course a transceiver like the K3, with a superhet architecture and
> > very narrow crystal filters, will outperform a zero-I.F. receiver in
> > close-in dynamic range (0-2 kHz). But the KX3 is no slouch.
> >
> > 73,
> > Wayne
> > N6KR
> >
> >
> >
> >
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-- 
Mickey Baker, N4MB
Fort Lauderdale, FL
*“Tell me, and I will listen. Show me, and I will understand. Involve me,
and I will learn.” *Teton Lakota, American Indian Saying.