As Eric alluded to, the entire Elecraft design team is safely working from home. We're busy adding new capabilities to the K4 and testing it in real-world conditions. (If it weren't for the lock-down, I and other early users would still be inviting operators over to try it. Previous demonstrations have led to amazement over the sound of the receive audio quality, among other reactions.)
With its new, faster DSP, versatile architecture, large display, and essentially unlimited code space, the K4 can offer features that go far beyond what we've been able to offer before.
Here's a sampling of what this will mean for SSB users:
*** Optimal audio
The K4's RX and TX passband in SSB modes can be configured to be flat from below 50 Hz to over 4 kHz, with none of the drawbacks of crystal filters (delay, ripple, passband edge effects). Easy to use graphic TX/RX EQ and other bandwidth controls allow the operator to tailor the response per-mode and for different microphones. The overall effect is full, rich audio in both transmit and receive -- the latter in full stereo.
Wider transmit and receive bandwidths can also be configured for digital audio modes, ESSB, and AM, at the operator's discretion.
*** Exceptional ALC performance
The K4 uses a new ALC system designed to completely eliminate power overshoot and varying loop dynamics. This makes it both easier to adjust and more compatible with external amplifiers.
*** Multi-parameter transmit metering
In voice modes, the K4 provides clear bar graph displays of all four transmit parameters simultaneously: power output, SWR, ALC, and compression (processing level). Real-time numeric readouts of power, SWR, supply voltage/current, and PA temperature are also available.
*** Foolproof split transmit indication
You'll never lose track of whether you're in SPLIT mode with the K4: all four transmit bar graphs are grouped either on the left (non-split, i.e. VFO A = TX) or right (split, VFO B = TX). TX icons are also clear and unambiguous.
The K4 also allows full cross-band/cross-mode operation in both split and non-split.
*** Versatile audio I/O
There are mic and headphone jacks on both the front and rear panels. Some operators prefer to use the rear panel connections to avoid cluttering the operating position. Audio for both voice and data modes can be either analog (LINE in/out) or digital (via USB or Ethernet).
*** Large DVR memory
The digital voice recorder draws on the K4's large pool of flash memory, allowing virtually unlimited expansion for both transmit and receive purposes. There are also new, easy to use playback controls.
*** Redesigned PA stages
All transmit stages have been upgraded, with improved biasing, parametric monitoring, and T/R sequencing. Hardware is also in place to support closed-loop amplifier IMD optimization, both internally and externally.
*** Support for future operating modes
With DSP and MCU horsepower to burn, we'll be able to add new voice and data modes in the future (and even new bands). The K4 is designed from the ground up for extensibility in both hardware and software.