KX3-2M Module FAQ



Q:  Can the KX3-2M module be installed along with other internal KX3 options, such as the ATU?


A:  Yes. The module is about the size of a credit card and only about 1/8” (4 mm) thick. It fits on top of the KXAT3 ATU module, and does not displace any of the other internal options.



Q:  What is the KX3-2M module’s power output?


A:  Maximum RF power output will be about 3 watts from an external 11-14 V supply, and 1 to 1.5 watts from internal batteries.



Q:  What is the receive sensitivity (MDS)?


A:  Typical MDS in the 2-meter band is about -145 dBm. Final specifications are to be determined.



Q:  What frequency range will the module cover?


A:  About 120 to 165 MHz, allowing copy of weather-band stations at 162 MHz, airport tower AM in the 120 MHz range, etc. However, sensitivity gradually falls off outside the 144-148 MHz ham band.



Q:  Can I use the KX3-2M module with 2-meter FM repeaters?


A:  Yes. The KX3 provides excellent repeater support, including programmable offsets, PL tones, REVerse, and up to 100 general-purpose labeled memories. Memories can be grouped for scanning and manual channel-hopping.  



Q:  What is the current drain on 2 meters?


A:  Current drain is typically 300-350 mA on receive and 1.5 A on transmit at 3 watts, running from a 14 V supply. Receive current is higher on 2 m than on the HF/6-m bands because we incorporated a high-dynamic-range, low-noise amplifier (LNA) in the front end. We're also working on a standby mode (when squelched) that should reduce average current drain to between 180 and 200 mA, depending on the dwell time selected by the user.



Q:  Is there any 144-148 MHz band pass filtering to limit strong out of band signals from pagers and other fixed services outside the band?


A:  Filtering is included at all stages of the receive path, including a 10-element band-pass filter ahead of the mixer. But because the module is so small, there's no room for a high-Q, tuned band-pass filter at the input; instead, we use low-loss low- and high-pass filters to preserve sensitivity. To reduce the need for narrow input filtering, we used a high-intercept LNA that is likely to do well in all but the very worst RF environments. This increases current drain of the radio on 2 meters somewhat compared to other bands, but we felt it was an acceptable tradeoff.


Since the KX3-2M module has its own antenna jack, you could use an external high-performance 144-148 BPF if required.



Q:  What is the frequency stability?


A: Standard (uncompensated) frequency stability is sufficient for FM or AM operation. For CW/SSB/data use, it will be necessary to perform the KX3's extended VFO temperature compensation procedure, providing typical stability of about ± 10 Hz on 2 meters. This range is compatible with 170-Hz-shift RTTY but is not compatible with many narrowband modes, including JT65 and WSPR.



Q:  Can I use the KX3-2M module as an I.F. for higher-band transverters?


A: Yes, with some limitations. First, it is important to distinguish between frequency-mixing transverters and frequency-multiplying transverters. If your high-band transverter uses a mixer, with the 2-meter module's output used directly without multiplication, then the total frequency stability will be a simple sum of the 2-meter module's and the transverter's. If however the high-band transverter uses frequency multiplication of the 2-meter I.F., the total stability can be a multiple of what is described above, and it may or may not suffice for your application. (Note that frequency-multiplication transverters are typically limited to CW use, only.)



Q: Does the KX3 support DTMF (dual-tone multifrequency signaling)?


A: Yes; the KX3's numeric keypad can be used to enter DTMF tones. After holding down PTT, tap "FREQ ENT" to enable DTMF entry, tap the desired digits (or hold for longer tones), then release PTT. All special DTMF characters are available on other KX3 switches:  ATU TUNE (*), MSG (#), MODE (A), A/B (B), DATA (C), A>B (D).