WITH KXPA100 IN, LOW SUPPLY VOLTAGE DOESN’T DROP KX3 TO 5 W: If the KXPA100 is connected via the special control cable, and PA MODE = ON, the KX3 will not drop out of QRO mode and go to 5 W at 11 V, as it does without the amp present. This allows the KX3+amp to be used with somewhat depleted 12-V batteries. The operator should monitor key-down battery voltage (e.g., by using the KX3’s “DISP” function) and reduce target power output if necessary. For example, if the key-down voltage is ~11 V, target power should be set no higher than 40-50 W. If it’s ~10 V, battery life should be conserved by using the KX3 at QRP levels. (To minimize current drain in this case, set PA MODE to OFF.) Some 12-V batteries, such as gel-cells, can be permanently damaged if discharged below about 10.5 V.
• TX GAIN MENU ENTRY FIXED: Wasn’t always displaying per-band drive power accurately in QRO mode (i.e., with PA MODE = ON).
• AM BROADCAST BAND (BCB) RECEIVE OPTIMIZATION: If you have a KXAT3 ATU installed, you can select one of two optimizations for reception below 1300 kHz. While in the ATU MD menu entry, tap ‘1’ (PRE) to select either BCB NOR (the original setting, which reduces the amplitude of received harmonic images), or BCB=160 (a new setting that may improve receive sensitivity by using the 160 meter ATU settings even below 1300 kHz). BCB NOR is recommended unless you need BCB=160 in order to copy a weak AM station. You can also improve sensitivity by using higher preamp gain settings (use the PREAMP menu entry, which is per-band).
• SUPPORT FOR HEIL HC-6 MIC ELEMENTS: Mic gain can now be set as much as 20 dB higher to support these low-sensitivity elements. NOTE: USE LOW “MON” (VOICE MONITOR) LEVEL IF MIC GAIN IS SET ABOVE 50. Otherwise you may hear acoustic feedback. Also, higher gain settings in general can make any transceiver more susceptible to noise pickup. If this is a problem, consider using a more conventional mic element that has greater output. The Elecraft MH3 has excellent frequency response, comparable to earlier Heil elements, yet it has far higher output than the HC-6.
