[Elecraft] [K1] K1 SN 3142 is alive! Plus questions...

[Mike Morrow]

Gil asked:

> ...what do you guys think of the usefulness of the noise blanker?

For years, I thought the KNB1 was only marginally useful, because only
rarely did I find a noise source for which it was effective.  But in
the past four years I've encountered in several locations, including
my home that an odd digital-type noise is present on some bands.  The
KNB1 has been very effective for that, and I've been very happy to have
it.  I stay away from using the noise blanker at its most extreme
setting (which is LO, meaning it triggers on a low signal threshold).
That can dramatically reduce receiver dynamic range.

> By the way, I just converted my 2-band board to 80/17, but the 17 side
> does not work, darn!  I must have messed-up somewhere because the board
> worked before on 40/20.

I converted my original 40/20m board to 80/17m after I built the
40/30/20/15m board.  It works fine, with a little better power output
on the 17m side than the 80m side.

I'm sure that you must have a simple problem on 17m, like maybe poor
solder connections to any of the six 17m band toroids (L2, L3, L7, L8,
L11, L12).  Does it receive?  The first thing I'd check is that a nearby
receiver can hear the 17m heterodyne crystal oscillator, which should
be heard about 26050 +/- 5 kHz when the 17m band is selected.

> By the way, what is that RF choke that came in the 80m kit?

It's a small 100 uH choke that installs in place of the jumper installed
at manual page 30 (upper right paragraph), which says:

"Locate the component outline for RFC8, on the bottom of the RF
board in the transmitter area. Install a short wire jumper at RFC8,
formed from a component lead or solid hookup wire.
Note: an RF choke may be supplied with the 80-meter band kit (2-
band Filter board only) for use at RFC8. This RF choke can be
installed at any time, and will have no effect on K1 alignment or
testing on any band. Its function is to improve stability on 80 meters
when the K1 is used with poorly-matched loads or an ATU."

Also specific to 80m use is C78, from manual page 45 (right side):

"Make sure that all component locations on the RF board have
been filled, except for two: J1, which is supplied with the noise
blanker option kit (KNB1), and C78, which may be supplied with the
80-m band kit for the 2-band Filter board. If you have the 80 meter
board, install C78 at this time on the bottom of the board near the PA
and 12V labels with the (+) lead oriented as shown on the outline.
Fold C78 down flat against the board before soldering."

I think that RFC8 and C78 should be supplied standard with every K1,
but for some reason they never have been.  Sometimes RFC8 is not even
supplied with an 80m parts kit, though it should be.

73,
Mike / KK5F