[Elecraft] maximizing useful K1 VFO range

[Wallace, Andy]

> -----Original Message-----
> From: SP5DDJ [mailto:sp5ddj@wa.home.pl]
> 
> I do regret that I made a choice of 80 kHz instead of 150 
> kHz, especially on 15m band. This made unable to use K-1 
> during last CQWW DX Contest single band 15m QRP.
> Many stations I've worked above 080 using another QRP rig.
> 
> But is it worth to make all alignment procedure again for a 
> single contest?

Wim, it's not bad at all. You don't have to do CAL OPF because 
those settings are for the band crystals, which won't change
when you go from 80 to 150. 

When I did my jumper-block-and-capacitors experimenting, I had
a 68pF cap for 80 kHz range permanently installed, and added a
jumper block to switch in another 47 pF cap, which brought me
up to 150 exactly. (My 68 + 47 = 115 pF)

What I would recommend is if you want the 150 kHz range temporarily,
tack a 47 pF cap on the underside of the board to the same pads that
the 68 pF C2 uses. This parallels it, which adds capacities of the two.

Then loosen the VFO toroid and adjust so the low end of
the band comes in...

Then redo the offset adjustment because that will probably have
changed in the switch (it did on mine). 

After doing that once or twice, it's not a long process. You
could do it the day before the contest.

As for leaving the 120 pF in, I found that after a couple of weeks
I wanted the 68 back. I had almost no trouble zero beating stations
and centering them in the (nice!) peak of the K1 filter, but the 
granularity of the ten-turn wirewound pot was showing itself, especially
at the very low end of the band. It sounds like you hear more activity
above 80 because of being in Europe. Here, I heard very very little.

-Andy