[Elecraft] K2 Lo P

[Jay Sissom]

Here's an update.  When the radio wouldn't come on after typing the
email, I was worried.  I found out my cigar adapter plug from Radio
Shack has a 2A fuse in it and it was blown.  So that would explain why
the radio wouldn't come back on!  With my other power wire, I should
be back in business.

73
Jay
W9IUF

On Fri, Jun 19, 2009 at 9:08 PM, Jay Sissom<jsissom at gmail.com> 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
>>>
>>
>