[K1] How about a KFL1-4 filter board for 17m/15m/12m/10m?

[Mike Morrow-3]

Curt wrote:

> Am planning build a KFL1-2 for 12 & 10M using some posts from late
> 2005 / early 2006 as guide.  Would appreciate hearing experiences
> of anyone else who has tried putting a K1 on 12 or 10.

I don't have any recommendations for this, but I would like to see a final
K1 product be a KFL1-4 four-band filter board for 17m, 15m, 12m, and 10m.
These bands are certainly possible on a KFL1-4, since 17m/15m and 12m/10m
have the appropriate relationships to easily operate below the rolloff of the
basic elliptical filter design used in the KFL1-4.  Such a board, plus the
necessary K1 circuit modifications for adequate performance up to 10m, would
be a real plus as the sunspot cycle climbs for the next five years.

I don't really expect to see this ever offered...the last K1-specific product
was introduced more than ten years ago.  But such a product would seem to be
relatively easy for Elecraft to produce, and a natural winner as these bands
roar back.  The KX1 can never cover **any** of these fantastic QRP bands...but
the K1 could cover all four on one filter board.  A backpack trip with the K1
and an easily erected 26-foot dipole segmented to cover all four bands would
be a real joy, at least until it got too dark.

It's something I'd buy even if I had a KX3, and especially if I had a KX1 (but
I'd need a K1 and the new board).  I can wish.

73,
Mike / KK5F
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[Curt]

When I asked question awhile ago about building one for 40/20/17&15, was
told the KFL1-4 requires that two of the bands be below 20M.  Wayne had
mentioned in one of the posts long ago potential for a KFL1-4H that would
accomodate just the higher bands, but that never bacame a product.

Agree with all of your points, especially that Elecraft has more profitable
items on their platter and isn't likely to revisit this old subject.  And
after all in another few years we won't be talking about 10M anymore.

I was hoping to find some folks who had implemented 10M on the K1.  While
changing filter boards is somewhat of a pain, seems this will provide the
most cost-effective means to get 10M QRP capability. Having 40/30/20/15 and
80/17 capability, 12/10 seemed to make the most sense.

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[Mike Morrow-3]

> When I asked question awhile ago about building one for 40/20/17&15, was
> told the KFL1-4 requires that two of the bands be below 20M.

That's half-true only if one does not alter **any component values**!  Duh!
Otherwise that statement was very incorrect at several levels.

The high band (20m, 17m, 15m) section of the existing KFL1-4 can already be
tuned to provide 17m and 15m rather than Elecraft's incorrect advertising claim,
plus structure of the KFL1-4 manual, that requires one to choose 20m and either
17m or 15m.  That denies the real versatility that exists in the present circuit.
I suppose someone assumes that no one would *ever* fail to choose 20m as one of
the bands.

So...a 17/15/12/10m KFL1-4 design is already **more than half** complete.  All
that would be required now is redesign the other RF section for 12m and 10m
instead of 40m and 30m, plus provide K1 circuit modifications required for
satisfactory 12/10m operation  I bet someone on Elecraft's engineering staff
could do the redesign in less than two hours, if time were available during
some future lull in Elecraft product output.  (No time soon, for sure.)

> And after all in another few years we won't be talking about 10M anymore.

Yes...a few...but one hopes that actually means something closer to seven years
or more.  (This is my fifth solar cycle in my ham life.  I recall that my first
in the late 1960s seemed the best.)

> I was hoping to find some folks who had implemented 10M on the K1.

I believe such folk do exist.  I'm not one of them, though.

> While changing filter boards is somewhat of a pain...

It is...especially with the KAT1 installed...hence the desirability of
a 17/15/12/10m KFL1-4 early in this cycle of increasing solar activity.
Also, low-pass filtering of the KFL1-4 is significantly better than that
of the two-band KFL1.

> ...seems this will provide the most cost-effective means to get 10M
> QRP capability. Having 40/30/20/15 and 80/17 capability, 12/10 seemed
> to make the most sense.

I have exactly the same filter board setups, plus a now-unused old two-band
KFL1 board from the days when the KFL1-4 wasn't available.  I'd consider
modifying it to a 12m/10m board if good component values were available.

But...the excellent little K1 has been off the burner for more than ten
years, and I suspect it is significantly more expensive to produce in kit
form than the KX1.  It probably does not make sense for Elecraft to strongly
encourage K1 sales if the KX1 can be sold in its place.  All this is only
my speculation!

I intend to acquire a full-house KX3 in 2012.  But I will never get rid
of my favorite QRP rig, my November 2000 K1 no. 175.

73,
Mike / KK5F
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