Wayne,
A: With preamp OFF, we measured about -125 dBm at 475 kHz and -90
dBm at 250 kHz. We have not measured MDS below 250 kHz, but the
receiver will gradually become less sensitive as you go lower in
frequency due to band-pass filter rolloff (in the KBPF3, which is
required for operation below 160 meters).
Would it make sense to update the KBPF3 to replace (or convert) the
0.5 - 2 MHz BPF to a 2 MHz LPF? Perhaps by removing L1/L2, changing
L4/L5 to 2.0 uH, removing C6 and connecting a new inductor (~10 uH)
between pins 2/7 of K2?
73,
... Joe, W4TV
On 2015-02-13 1:27 PM, Wayne Burdick wrote:
In response to a gazillion questions:
* * *
Q: What is involved in upgrading from the KSYN3 to the KSYN3A?
A: The KSYN3A plugs into the same connectors as the KSYN3s for the main and
sub synthesizers. There are minor differences in cable routing that are covered
in the accompanying installation instructions. No user calibration is required
for the KSYN3A, simplifying the installation process. Version 5.10 or later K3
firmware is required (presently available on our web site as a beta release).
Q: Will the new synthesizer module be included in future orders of the KRX3
sub receiver?
A: Yes. But we also have limited quantities of the original synthesizer boards
for those with existing K3s who wish to add a KRX3 but not upgrade the synth.
Questions on specific orders should go to [email protected].
Q: What is the approximate 2-kHz dynamic range (IMDDR3) of the K3 when using
the new synthesizer?
A: Our tests show in excess of 105 dB with the narrowest filters, though there
are many factors, and this should be considered approximate. (A very robust
test setup is required to make these measurements.) A third party has obtained
similar results, but they have not published them yet. When they do, we will
update this FAQ.
Q: How much lower is the KSYN3A's phase noise than that of the original KSYN3?
How does this affect signals?
A: At an offset of 2 kHz, the KSYN3A's phase noise is typically 15 to 20 dB
lower on a given band. Generally speaking, this means a smaller increase in the
noise floor in receive mode in the presence of very strong close-in signals.
The limiting factor would then be how clean everyone else's signals are. Your
own transmit signal will be cleaner when using the KSYN3A, though the K3
already has one of the cleanest transmitters available, accounting for its
popularity with DXpeditions and multi-transmitter contest stations.
Q: What is the K3's 100-490 kHz receive sensitivity? What signals would I find
in this range?
A: With preamp OFF, we measured about -125 dBm at 475 kHz and -90 dBm at 250
kHz. We have not measured MDS below 250 kHz, but the receiver will gradually
become less sensitive as you go lower in frequency due to band-pass filter
rolloff (in the KBPF3, which is required for operation below 160 meters). These
tests were made with the signal routed through the RX ANT IN or XVTR IN jacks
on the KXV3 option module. The preamp is not effective in this range and must
be turned off. A sub receiver (KRX3) fitted with a KBPF3 should have similar
performance, whether the signal is obtained from the main path (KXV3) or from
the sub's AUX RF input.
As for signals: there's the 600-meter band (more on that below), a large number
of commercial CW beacons (for example, see www.dxinfocentre.com/ndb.htm), and
other interesting phenomena. We've just begun to explore it ourselves!
Q: Will I notice any change in performance if I upgrade to the KSYN3A?
A: First there's the obvious -- the ability to tune the VFOs much lower in
frequency. If you're a high-speed CW operator, you should be able to hear an
improvement in CW element timing at high code speeds, as well as somewhat
faster receive recovery. The dynamic range of the K3 was already excellent, and
its phase noise very low, so you might notice the additional improvement in
these parameters only in very difficult signal conditions.
Q: How does the new synth affect CW operation?
A: The KSYN3A switches faster than the KSYN3, which allows us to more precisely control CW timing. This means less
"jitter" (timing variation) at high CW speeds. Many CW operators who had been using "QRQ" mode (CONFIG:CW
QRQ=ON) for CW in the 35-60 WPM range will now be able to use normal CW mode (CW QRQ=OFF), meaning they no longer give up RIT and
SPLIT when using fast CW. Receive recover times also improve. Note that we recently introduced a variation on CW break-in signal
processing called "NEW QSK" (selected by tapping '3' in the CW WGHT menu entry). This eliminates audio T/R artifacts
heard with the original algorithm ("OLD QSK"), at the expense of some slowing of receive recovery (by purging the DSP's
"pipeline"). Installing a KSYN3A speeds up receive recovery for both the OLD and NEW QSK settings.
Q: What is required to use the 600-meter band?
A: This band is available in some countries, often on an experimental basis.
Specific restrictions may apply. A K3 fitted with a KSYN3A, as well as a KXV3
and KBPF3, can receive signals on this band, and can put out about 1 milliwatt
of transmit power. An external amplifier will be needed, connected to the XVTR
OUT jack. At present we don't have information on such amplifiers. You can also
get on this band using an up-conversion transverter whose output is on a low HF
band (also not presently supplied by Elecraft). For a general introduction to
the 600-meter band, see:
wikipedia.org/wiki/600-meter_amateur_radio_band
Q: Can a transverter I.F. of "0" be defined as an alternative to setting
CONFIG:KXV3 to TEST?
A: Not at this time, though we hope to add this capability. Those who
frequently alternate between TEST and NOR modes can assign the KXV3 menu entry
to a programmable function switch, or write a switch macro to change this menu
setting as well as set up the VFO, preamp, etc., for this band.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
