[Elecraft] KSYN3A FAQ

[Wayne Burdick]

In response to a gazillion questions:

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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 sales at elecraft.com.


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.