[Elecraft] Need a few testers for new K3 firmware, rev. 5.03

[Wayne Burdick]

Hi all,

The latest K3 field-test firmware has just one new feature, one that will only rarely come into play: overdrive protection at the KPA3's input. 

The efficiency of any power amplifier stage will be reduced if operated into certain reactive loads, and/or with reduced power supply voltage. In the case of the KPA3, this will normally be determined by the K3's transmit current drain, temperature, and reflected power measurements, allowing the transceiver to quickly reduce power output to a safe level. This will protect the KPA3 even in the presence of an open load or a dead short.

The latest firmware provides an additional margin of safety by putting an upper limit on drive power into the PA stage. Those who use the K3 in the field, especially with ad-hoc antennas or 12-V batteries, would be the most likely beneficiaries. For example, when the operator requests maximum power but is running from a somewhat depleted battery, the drive limit might be reached prior to other limits. This would reduce power output, automatically conserving battery power while keep amplifier efficiency high.

You'll need a 50-W-capable dummy load to test this new firmware. The maximum drive allowed is based on data obtained during per-band 50-W TX GAIN calibration, which must be redone after updating to rev. 5.03.

Please email me directly if you can test this new firmware today or early tomorrow. We'd like to go to beta very early next week.

73,
Wayne
N6KR