[Elecraft] KX2 SWR measurement BYPASS vs AUTO

[w4sc]

Anomaly with KX2 SWR measurement BYPASS vs AUTO.  This was noted during a power out on all bands of the “TUNE” function with ATU in BYPASS.

Initially KX2 was matched using the ATU on various bands with antenna presenting load not ideally matching 50 Ohms.  The line SWR was > 4:1 in some cases (measured in ATU BYPASS).  The matched (ATU AUTO) SWR indicated 1.2 or 1.3 : 1 on each band.

Connecting a 50 Ohm load and using an Oakhills Research Wattmeter, a check of the power out was performed for all bands using the TUNE (3W) function in the ATU BYPASS mode.  The SWR as measured by the KX2 indicated 1.2:1 on each band.  Power out ranged 3.8W (80M) down to 3.2W (10M) as measured on the watt meter, which is acceptable.  Reflected power was essentially “0” on all bands.

Setting the ATU back to AUTO, and performing an ATU TUNE on all bands, then resulted in an indicated SWR of 1:1 using the TUNE(3W) function.

Setting the ATU back to BYPASS, the SWR as measured by the KX2 indicated 1:1 when TUNE (3W) was initiated on each band.

Is there an issue with the way the fw updates the SWR measurement for display?

Ben W4SC