[Elecraft] K1 band change Issue

[Mike Morrow]

Bill wrote:

> ...What I observed is when the Band switch is used
> to cycle through the bands 30 meters does not show up in the display, but
> 20 meters appears to show up twice.

The K1 does *not* know automatically which bands are available on any
filter board that is plugged in.  That is why the procedure at the bottom
of page 16 of the KFL1-4 manual (rev. A) must be used to manually tell
the K1 MPU what bands the plugged-in filter board possesses.

Completing that assignment process causes the K1 to format the frequency
display (LCD) as appropriate for the assigned bands.  In addition, each
amateur band 160m, 80m, 40m, 30m, 20m, 17m, 15m, 12m, and 10m has a
band-specific display frequency calibration constant stored in the
K1 MPU.  This constant is set automatically when you perform the OPF
(operating frequency) calibration for that band (page 18 of the KFL1-4
manual).  So...the other thing that happens (in addition to LCD formatting)
when you assign a specific HF ham band to band b1 (b2, b3, b4) is that
the previously-stored OPF calibration constant for that ham band is
automatically assigned to band b1 (b2, b3, b4).

Aside from that, a band assignment does **not** actually affect the
operation of the rest of the K1.  You could manually assign *all* bands
as 20 meters, yet when you cycle through band b1 (b2, b3, b4), the K1
will still actually still function on 40m (30m, 20m, 15m), even though
the displayed frequency *appears* to be 20m for each band.

> One of the appearances of 20 meters functions, but the other does not,

That seems to describe your seeing 7.xxx, 14.xxx, 14.xxx, 21.xxx in the
LCD as you cycle through the bands.  (Normally you should see the repetitive
display of 7.xxx, 10.xxx, 14.xxx, 21.xxx as you cycle through.)  If that
is correct, then which of the two 14.xxx bands does not function?  If the
one that doesn't work is the first 14.xxx after 7.xxx, then apparently
you have a problem with band b2 on you KFL1-4...the band position that
should be 30m.  Just re-assigning b2 to 30m (either 10.000 for an 18.000
MHz filter board crystal or 10.100 for an 18.100 MHz filter board crystal)
will *not* fix the non-functioning band.  You should go ahead and assign
b2 properly, but then your real troubleshooting begins.

OTOH, if the band with the *second* "14.xxx" display is the one that is not
working, you have troubleshooting to do on your 20m filter circuitry.  The
30m circuitry is likely OK, although K1 b2 needs to be re-assigned to 30m.

As far as troubleshooting a bad 30m band, you could attempt to re-align the
30m (b2) capacitors on the KFL1-4 per its manual.  However, that will also
then require re-aligning the 40m band as well.  (Part of the 40m resonant
circuits make use of the tuning circuits of 30m.)

If you are not successful in returning the 30m band to operation by
re-alignment, then you'll need to look for another failure.  The most common
reason for a K1 band to be totally dead is a bad heterodyne crystal on the
filter board.  Do you have a receiver that could be used to hear the 30m
crystal near 18.000 or 18.100 MHz (+/- about 10 kHz), when b2 is selected?

> ...which is likely 30 meters not being recognized and showing up as 20
> meters.

Definitely not.  The only way your K1 knows what ham band is assigned to b2
is from the band assignment that must be performed manually.   The K1 does
not sense or otherwise know if any or all bands on a filter board are working
or dead.  The only information that the filter board gives to the front panel
MPU (the central 'brain' of the K1) is whether it is a two-band or four-band
filter board.  That way the K1 knows whether to let you assign a specific ham
band to just b1/b2, or to b1/b2/b3/b4.

That part is definitely working.

Mike / KK5F