Fw: [Elecraft] K1 frequency range ??

[Mike]

Chuck Roedel wrote:

> K1-4 #992 is up and running!

> frequency range is from approximately  6.090mHz - 7.079 (other bands
> same 10kHz below band edge).

You are lucky if all the other bands also start the same 10 kHz below
band edges.  That means all your KFL1-4 crystals are oscillating at the
same amount of departure from the nominal value for each band.

As has been pointed out in the postings of others, slightly compressing
the turns of L1 (to LOWER the subtractive VFO) on the RF board will
RAISE the operating frequecy for ALL four bands by the same amount.

If you really want to ensure sufficient frequency coverage, you could
increase the value of VFO capacitor C2 from the 68 pF supplied.  I used
the supplied 120 pF capacitor and got a 170 kHz tuning range, which I
like VERY VERY much!  I have found, IMO, there to be NO disadvantage
associated with the wider tuning range, and it is particularly valuable
on the K1-4, since it allows complete coverage of the 40m CW band and
almost all of the 15m CW band (not all interesting QSOs take place on
the low ends).  I did, however, linearize the VFO tuning rate greatly by
the simple addition of a 100 K ohm resistor from the hot side to the
wiper of the VFO pot, and I installed some soft felt washers behind the
VFO knob and the panel to put a little drag on the tuning.  I'd have
done both of those additions even if I had used the 80 kHz range option.

Others have chosen values of C2 between 68 and 120 pf to get
intermediate tuning ranges.  You'd need to chose any capacitor
characteristics carefully to minimize temperature vs. capacitance
effects on VFO stability.

Mike / KK5F