Field Day Operating Tips (including some KX3-specific)

[wayne burdick]

ARRL Field Day--my favorite operating event--is this weekend. Last  
year only one KX3 was on the air for Field Day (my prototype). We  
should improve on that this year!

Of course we expect to hear lots of K1s, K2s, K3, and KX1s, too. Our  
entire product line is targeted at field operation, and it's been very  
gratifying to see so many of our customers excel in their operating  
class or section.

Here are a few important tips. Please forward them to any interested  
operators or clubs.

1. Bands:

20 and 40 meters are typically the "workhorse" bands. 20 meters will  
be packed the entire time. 40 meters really heats up in the late  
afternoon after it starts to go "long," and is often very active for  
local contacts near the end of the contest, on Sunday morning. 80  
meters may contribute significantly to your total if you have a decent  
antenna and the noise level isn't too high. Also, don't overlook 15  
and 10 meters. Even at night (as late as 9-10 PM in my experience) you  
can "run" lots of stations at QRP levels on these bands, for a couple  
of reasons: atmospheric noise is often very low, and there will be  
many stations with full-size 10 and 15 meter antennas looking for  
QSOs. Of course if you have 6- or 2-meter capability, too, you should  
work all the locals--every QSO counts.

2. As with any Field Day setup, mutual interference between stations  
in close proximity is a possibility:

If you're operating a KX3 in the same band segment as another radio,  
e.g. 40 m CW, you may hear the KX3's VFO on the other receiver as a  
continuous carrier when both are tuned to the same frequency--a side-
effect of the zero-IF architecture. If this occurs, simply set MENU:RX  
ISO to ON. This turns on the KX3's receive isolation buffer, which  
reduces the amplitude of VFO signal leakage at the antenna jack by  
some 70-80 dB. It adds 10-15 mA to receive-mode current drain.

If the KX3's receiver experiences "AM detection" (broadband, non-
tunable interference) from a transmitter in very close proximity, take  
one or more of the following steps:

   (a) [best idea!] separate the two stations' antennas as much as  
possible

   (b) Set MENU:RX SHFT to 8.0 instead of NOR on any affected band
       (note that, at present, this prevents the use of dual watch
       on these bands)

   (c) turn the preamp OFF on any affected band (and/or use the  
attenuator)

If the KX3's receive carrier-operated relay is heard clicking on/off,  
then the other transmitter's antenna must be *really* close. Only (a)  
above can help in this case.

High-power band-pass filters at the antenna jack of one or both radios  
are another often-used solution to the mutual-interference problem.  
These can easily be home-built, and at QRP power levels can be made  
quite small.

3. Battery life can be improved by minimizing the KX3's receive and  
transmit current drain. I recently posted on this topic, and have  
included the text below in its entirety.

4. Listen more than you transmit. You will often be more successful  
using hunt 'n' pounce, rather than calling CQ, at QRP power levels.  
This is also an excellent way to conserve battery life.

See you on the air!

73,
Wayne
N6KR

Receive

The KX3 already has far lower receive-mode current drain than most all-
band/all-mode transceivers, but you can further reduce it in several
ways:

- use headphones (10-100 mA saved depending on volume level)
- turn off the LCD backlight (25 mA)
- turn off the RX I/Q port when not needed (10 mA; see MENU:RX I/Q)
- turn off the preamp (5 mA saved for the 20 dB preamp,
   10-15 mA for the 10-dB preamp)
- turn off the RX isolation amp (10-15 mA; see MENU:RX ISO)

Using all of the above techniques, receive-mode current drain can be
as low as 150 mA, varying a bit per-band.

Transmit

In transmit mode, current drain varies with power level, supply
voltage, band, and load impedance. An antenna tuner (such as the
internal KXAT3 option) can help ensure the transmitter sees a good
match.

There are some thresholds where the transmit current drain is
automatically reduced by switching in a higher-impedance PA output
transformer winding. In this case a decimal point is added to the
right of the power display when you adjust it (e.g., "3.0 W."). Here
are the conditions under which TX current is reduced:

1. 5.0 W or less in CW, FSK-D, and FM modes when key-down supply
voltage is 11 V or higher

TX current in this case is typically 1 amp -- about 50% lower than
what you'll see if you move power just a bit above 5.0 W. This is
especially useful for QRP Field Day outings (etc.) where the rig is
powered from an external 12 to 14 V battery.

2. 3.0 W or less in all modes, regardless of supply voltage

This is the generally recommended power level when operating from an
internal NiMH battery pack. If you're more interested in power output
than operating time, you can run up to 5 watts from the internal
battery.





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[Edward R Cole]

Noted in the "tips" the following:
--------------
Here are the conditions under which TX current is reduced:

1. 5.0 W or less in CW, FSK-D, and FM modes when key-down supply
voltage is 11 V or higher
--------------
Can I take from this that FM Mode has been implemented in the KX3
firmware?  It hadn't in earlier versions.

This would be good news since I will immediately be using my KX3 with
a 144-28 transverter on 2m-FM when I have the KX3 constructed and
installed in the shack.  No this is not the KX3-2M module should
anyone ask.  Hope that will be coming out soon for beta-test.

I should have my KX3 by July 2nd (at latest).



73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
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[Lyle Johnson]

Ed,

You'll be happy to know that FM has been in the KX3 firmware since MCU
00.87/DSP 0.80, released 04 April 2012.

73,

Lyle KK7P

> --------------
> Can I take from this that FM Mode has been implemented in the KX3
> firmware?  It hadn't in earlier versions.

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