[Elecraft] K3 Beta Release: 2-Meter frequency locking to REF CAL and External Reference

[Wayne Burdick]

K3 beta-test firmware revision 4.42 (with DSP rev. 2.73) is now  
available. This release allows the offsets for the 2-meter ref-lock  
option (K144RFLK) to be automatically calibrated based on the REF CAL  
menu parameter. Since REF CAL can track an external 10-MHz reference  
(via a K3EXREF module), 2-meter users can now obtain exceptional  
frequency stability. See detailed release notes below.

Please send any questions to k3support at elecraft.com. For instructions  
on how to load beta firmware, see:

      http://www.elecraft.com/K3/k3_software.htm

73,
Wayne
N6KR

* * *

MCU 4.42 / DSP 2.73, 8-24-2011

* 2-METER FREQUENCY LOCKING TO REF CAL & EXT. REF:
The K144XV RFLK option locks the K3's 2-meter module to the rig's
master reference. Previously, users of this option had to enter offsets
in the CONFIG:XVn OFS menu entry based on how far off the
master reference was from 49380.000 kHz. These offsets can now
be calculated automatically based on the REF CAL menu entry.
If a K3EXREF module is also installed, then REF CAL itself
is automatically calibrated based on an external 10-MHz reference
(see K3EXREF on 2 m, below).

To enable this, locate XVn OFS in the menu, then tap ‘0’ until you see
“REFLOCK”. This lets the K3 firmware know that the RFLK module is
installed. (If the RFLK option is not installed, then the K144XV’s
oscillators are not locked to the K3’s master reference. The offsets
should then be set according to the label on the transverter module.)
To see the automatically calculated offset value in the XVn OFS
menu entry, the K3 should be switched to the 2-meter band. Otherwise,
the K144XV offset parameter may be initially displayed as "-0.00".

K3EXREF on 2 m: If a K3EXREF module is installed, REF CAL itself
will be automatically calibrated based on an external 10-MHz reference.
In this case, selecting “REFLOCK” for XVn OFS will allow the K144XV
frequency to track this external reference. 2-meter frequency accuracy  
will
be about a factor of around two worse than on HF, due to the higher
frequency of the 2-meter local oscillators.

* K3EXREF REF CAL VALUE SAVE: In REF CAL, tapping '1' will
now save the K3EXREF-derived reference value as the manually
entered value. This is useful in the event that the K3 is ever
disconnected from the 10-MHz reference, as it will revert to the
manually entered value. Note: To use this feature, a K3EXREF
module must be installed, a 10-MHz external reference connected,
and an asterisk (*) be present in the menu entry name (“REF*CAL”).
You can then tap '1' to save the value.

* NO ERROR TONE ON KPA500 OPERATE/STANDBY
SWITCHING, etc.: Previously, the K3 would emit an error
tone on any KPA500 switch event. Now such tones are
only emitted if the CONFIG:SW TONE menu entry is set
to ON, or on a hard fault.