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KX3 Application Notes

 Application Note Description Production phase-in details (if applicable)
Elecraft KXPA100 + KX3 Power Calibration This optional calibration procedure pairs a specific KX3 to a specific KXPA100 for maximum accuracy between requested RF output and actual output. It is optional because the KXPA100 is factory calibrated to an Elecraft lab-standard KX3 transceiver, measuring and saving expected KX3 drive power for a given KXPA100 output power. See the Application Note for the tools required to complete it.
Tuning Noise Suppression Modification KX3s with the KXFL3 filter installed may exhibit noticeable "zipper" noise when the VFO is tuned on quiet bands. This Application Note discusses how to determine if your KX3 needs the modification and how to do it.

Applied to factory assembled KX3s from serial number 4668 up, and kits from serial number 4753 up that include the KXFL3 option. KX3's shipped after to not have the problem.
KX3 160M/80M Rx Performance Improvement The KX3's receive dynamic performance has been improved by approximately 10dB on the 80M and 160M bands only. Operators on these bands may recognize improved performance with strong local interference with this modification in place. This App Note discusses how to determine if you will benefit from the Performance Improvement and whether your KX3 needs to have it installed.


Allows receive opposite-sideband suppression to be optimized on any or all bands, relative to the normal level of suppression. Requires S9 to S9+30 signal source on each band to be adjusted. This is applicable to KX3's below serial number 2324.
KX3 VFO TEMPERATURE COMPENSATION Improved frequency stability is available for some of the new Digital Modes, such as JT65. It is also recommended when installing the 2M Option after the KX3 was purchased or if you are building the KX3 from a kit. If you purchased your KX3 factory-built with the 2M Option installed at the time of purchase, the factory performed this procedure for you.
KX3 Improving Internal Speaker Performance If you have occasional loss of audio or crackling sounds coming from your KX3’s internal speaker, especially at high volume levels, see this short Application Note for details on how the connector is to be oriented.
Builder Alert: Battery tray mounting screws The 2-56 flat head screws used to attach the battery trays fitted inside the KX3 may not seat smoothly against the plastic holder. This Application Note discusses how this can be addressed. KX3 Kit Builders should check their battery tray installation using this Application Note. All Factory-built KX3's will not have the problem.

KX3 Mobile Installation And Operation guide

KX3 article on Mobile Installation and Operation by Matt Zilmer, Rev 1.6 (November 23, 2012)

KX3 Block Diagram (.pdf)

KX3 Block Diagram (March 27, 2012)

KX3HSMDKT (.pdf)

KX3HSMDKT Enhanced Heat Sink Installation Instructions Rev B (6-17-2015)

KX3 Speaker Grille Instructions (.pdf)

KX3 Application Note Installing Speaker Grille