[Elecraft] [KX1] Need additional troubleshooting steps for inoperable KXAT1

Scott Wright emergentbehavior at yahoo.com
Sun Mar 15 00:08:34 EDT 2009


I'm having trouble with my KXAT1.  More specifically, (1) I can't get
the power reading to adjust up to anywhere near the actual TX power and
(2) the SWR reading with the DL1 dummy load attached is 9.9, which I
assume is not a good thing.

Here are the data bits:

1)  There's no 30/80m module.

2)  I ohm'ed out the DL1 and it reads 50.1 ohms.  Close enough.

3)  With the R1 pot set at ~50%, the KX1's power display is 0.7 watts in
'tun' mode.  The power reading at the DL1 is 3.6 watts, which is pretty
much the same reading I got after I finished the KX1's transmit section
(before adding the AT).  Cranked fully CW (?), the maximum displayed
power reading is 2.1 watts on the KX1.

4)  During calibration, nulling the voltage on the REFL test point
results in a voltage of approx 1.75 volts.  I've seen posts on the
reflector where folks are getting nulls well below 1V.  I suppose this
isn't a good thing, either...

5)  I ohm'ed inductors L1, L2, and L3 after installation and all three
read <0.3 ohms.  I'll assume that means good stripping/tinning/soldering.

6)  I tried ohm'ing transformer T1 after it was installed to see if I
had any shorts but I'm reading <0.3 ohms across any combination of
leads.  This (sorta') makes sense -- given how it's gonna' react to DC
-- but doesn't tell me anything.

7)  I quadruple checked my installation of T1.  The picture and notes in
the assembly manual are a bit confusing and unlike all other Ls and Ts
I've installed so far, the footprint/silkscreen for T1 doesn't line up
with how the winding is described.  What looks like a clean, drop-in
install results in -- as I read it -- incorrect phasing.  Matching T1's
wiring diagram / picture to its silkscreen forces the leads to run under
the toroid in a "contorted" fashion.  As ugly as it was going in, that's
how I have it soldered in place.

8)  When instructed to tune, the resultant SWR is always displayed as
9.9.  (I can hear the relays clicking on-and-off in rapid succession
during the tune...)  I tried the inductor/capacitor test outlined in the
KXAT1's troubleshooting guide, but regardless of the L0/1/2/3 or
C0/1/2/3 setting, the SWR always displays as 9.9

So, I'm at an impasse.  I don't wanna' start randomly removing
components -- I haven't yet had to remove a single component from the
KX1 or the AT -- but I'm at a loss as to what to do next.

Are there any other troubleshooting steps??  I'll never claim to be a
guru on this stuff -- in fact, I'm not 100% certain how an AT even works
-- so any additional guidance would be greatly appreciated.

Thanx!!

Scott
AC0FQ
KX1 s/n 2177


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