[Elecraft] K2 Lo P

Sun Jun 21 10:55:09 EDT 2009

Oops, I sent this to Don by himself, but thought I should send it to
the list just in case it helps someone.

Thanks Don, just an update. I re-nulled C55 and it nulled fine.  When
I checked the voltage at U4 pin 1, it was 2.8V which was a little low.
 Then I set R1 & R2.  After doing that, the SWR into a dummy load is
1:9.9.  I'll take the antenna tuner apart and look to see what I can
find.

Thanks & 73
Jay
W9IUF

On Sat, Jun 20, 2009 at 12:46 AM, Don Wilhelm<w3fpr at embarqmail.com> wrote:
> Jay,
>
> It really sounds as though you have a problem with the wattmeter in the
> KAT2.
> Try balancing and calibrating the wattmeter again.  If you cannot achieve a
> good null with a good 50 ohm non-reactive dummy load, check T1 and its
> associated components (T1 for well tinned and soldered leads and C34, R3,
> R4, D1 and D2 for god soldering and proper orientation).
>
> If you cannot achieve a good null when balancing the wattmeter, stop and ask
> for specific help.  The null is a pre-requisite to proper calibration.
>
> 73,
> Don W3FPR
>
> Jay Sissom wrote:
>>
>> 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
>>>>
>>>>
>>
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