[Elecraft] K2 Lo P

[Jay Sissom]

Don (& list),

I started doing some testing tonight and have narrowed it down.

I took out the antenna tuner and tested each band at the 2W setting,
5W & 10W setting on the power knob.  I have an external watt meter and
dummy load attached.  The power didn't match exactly on all the bands
but it was fairly close (between 1.9W - 3.5W on 2W setting, 4.9 - 7W
on 5W setting and 9W - >10W on the 10W setting).  My Oak Hill WM2
meter only goes up to 10W.

Then I re-installed the antenna tuner and started the test again.  I
connected to Ant 1 and had the ANT setting set to CALS.  On 28060 the
2W setting measured 2W on the meter but gave an SWR of 1.4.  At 5W it
was SWR 1.5 and at 10W it was SWR 3.  The other bands were similar.
When I got to 21060 at 10W, the display said Hi Cur then showed an SWR
of 3.  At 10106 with 10W, it also said Hi Cur then the radio shut down
and wouldn't come back on.  I don't smell smoke or anything so I'm
assuming the fuse reset and I'll need to wait for it to cool down.

So it is definitely a problem with the antenna tuner.  I think this
has already identified a problem and I shouldn't keep going with this
test.  I'll take the antenna tuner out of the lid and look at it in
more detail.  But of course, any other ideas would be appreciated.

Thanks & 73
Jay
W9IUF

On Fri, Jun 19, 2009 at 12:56 AM, Don Wilhelm<w3fpr at embarqmail.com> wrote:
> Jay,
>
> The real answer is "it all depends".
> Since this is a very recent K2 serial number, it may be that this problem
> has been present since it was built and was the reason that the original
> builder sold it - that is an unfortunate situation, but it must be
> considered.
>
> First, set your CAL CUR to 3.50 amps and try again.
> LoP indicates that the K2 is not developing adequate power to enable proper
> tuning for the KAT2 (it needs 2 watts to tune).
>
> Then set the K2 ATU menu to CALP and see if it will do a TUNE into a dummy
> load - first try at 5 watts power requested, then 10 watts and finally at
> maximum requested power.  Does the HI-CUR message appear at all those power
> levels?  Or only at maximum power?
> Next, try each band separately (doing the tests as above).  Does the HI-CUR
> message appear on every band? or only some bands?
>
> After those tests, set the ATU menu to AUTO and do a "TUNE" into the dummy
> load.  You should hear some relays click and after the tuner has set its L
> and C values to match the 50 ohm load, it should exit from TUNE.
>
> If all that does not produce satisfactory results, there is something wrong
> with the K2.  To troubleshoot it, the first step is to remove the KAT2 and
> operate the base K2 directly into a 50 ohm non-inductive dummy load.  If it
> does not produce good power output without HI Cur messages, then there is a
> problem with the base K2 - likely in the Low Pass Filters or with the T4
> output transformer.  We can help further if we have more specific
> information - what bands fail? what bands work? How much power is really
> produced?
>
> 73,
> Don W3FPR
>
> Jay Sissom wrote:
>>
>> Hello, I'm helping a friend who purchased a used K2.  The K2 is a
>> serial number 6xxx with a KAT2, KSB2 and KBT2.
>>
>> When tuning with the antenna tuner into a dummy load, sometimes The
>> message "Lo P" appears on the display.  It would also give the "Hi
>> Curr" message with the current limit set to 2.5A.  Does it seem right
>> that the radio would draw that much current when tuning into a dummy
>> load?
>>
>> Any info on this would be appreciated.  I'm finishing up the DSP, 160m
>> and KNB2 options for the radio but would like to get this fixed before
>> making changes.
>>
>> Thanks & 73
>> Jay
>> W9IUF
>>
>