[Elecraft] How to put an Elecraft K2 on 60 meters (updated)

[Phil Wheeler]

Sounds like a lot of hassle for five "channels".  Of course, if you want 
those channels, likely no quicker way to get them.

Phil

Wayne Burdick wrote:

>Our K60XV option (60 m + transverter I/O) isn't available yet, but it looks like
>U.S. hams will get limited privileges (USB mode only, 5 discrete frequencies) as
>of July 3rd. So we thought we'd update and re-post information on how to put the
>K2 on 60 meters for those who are anxious to try out the band now. K2 firmware
>does not at present include 60 m in the band map, so the modification works by
>"sharing" 40-meter components. 
>
>Note: This modification is recommended for experimentation only, as we have not
>yet fully characterized the K2 on this band. However, a few hams in the UK have
>made these changes successfully, and our own initial tests show that performance
>is the same as on the other bands.
>
>1. The 40 meter band-pass filter must be resonated on 60 meters:
>
>Install a DPDT switch on the rear panel, close to the 40-m band-pass filter. The
>two switch commons should be wired to either side of C6, the top coupling cap in
>this filter. In the 60 m switch position, a 4.7 pF capacitor should be placed in
>parallel with C6. From either side of this capacitor to ground, you'll need a 50
>pF trimmer and a 47 pF fixed cap, in parallel. The filter will be peaked later.
>
>2. Memories can be set up for easy 60m or 40m access:
>
>Turn on the K2 and switch to 40 meters. Select the 1-kHz-per-step VFO tuning
>rate and tune the VFO down from 40 m to the center of the 60 meter band (~5.3
>MHz). Hit A=B to set both VFOs to this frequency, then STORE the setup in a
>frequency memory (I used #5 since this is 5 MHz). Then tune back up to 40
>meters, hit A=B, and STORE this in another memory (#7 makes sense: 7 MHz). Now
>you can jump to either 60 or 40 meters using the RCL button. Of course you could
>assign up to 5 memories for use on the new channelized 60-meter assignments.
>
>3. The VCO requires additional capacitance:
>
>Use RCL #5 to get back to 60 meters. The PLL will be out of lock because the
>40-meter VCO capacitance is too small to allow the VCO to tune down to 5.3 + 4.9
>= 10.2 MHz. To get the PLL to lock, you'll have to parallel some 30-70 pF of
>extra capacitance across C71. Connect a voltmeter to R30, and find a value of C
>that results in a VCO voltage of 1.5-7.5 V over the desired 60 m segment. Then
>install a tiny SPST switch on the board which, when thrown to the 60 m position,
>puts this cap into the circuit. Use very short leads, and cut an access hole in
>the bottom cover. (Note: the K60XV will be supplied with two MV209 varactor
>diodes, D19 and D20, that will work in combination with the K2's new "D19" menu
>entry to change the VCO tuning range so that it covers both 40 and 60 meters
>with new VCO relay combinations. You don't need new K2 firmware to use the fixed
>capacitance method described here. But if you have it, leave "D19" set to "N".)
>
>4. With both the VCO and BPF switches in the 60 m position, and a 60-m memory
>recalled, align the BPF trimmers on 60 meters in RX or TX mode.
>
>5. The K2's original 40-m low-pass filter and push-pull PA does a decent job of
>suppressing the 2nd harmonic on 60 meters, but if you want some extra margin,
>use the new 40m/60m elliptic low-pass filter components shown in the Revision D
>K2 manual. These components are already present in K2s s/n 3000 and up.
>
>You're now ready to use the K2 barefoot on 60 meters (up to 15 W). Remember to
>use upper sideband *only* as we haven't yet convinced the FCC to let us use CW 
>:(  
>
>The KAT2 and KAT100 automatic antenna tuners will both work on this band, so you
>can use a 40 or 80-meter antenna or a random wire.
>
>DO NOT use the KPA100 on 60 meters unless you have the means to check 2nd
>harmonic suppression. Since the KPA100 uses a 40/30 meter low-pass filter, the
>2nd harmonic attenuation on 60 meters would be determined solely by the balance
>of the PA strip, which may or may not meet FCC specs. A future modification to
>the KPA100 will allow use on 60 meters. (Also note the carefully-defined 50-watt
>power limit on this band. See www.arrl.org for details.)
>
>Now: Who will be the first to work all states on 60 meters? (Probably no award
>certificate....but don't let that stop you!)
>
>73,
>Wayne
>N6KR
>
>------
>
>www.elecraft.com
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