[Elecraft] KX3 Intermittent changes in audio gain

[Matt Zilmer]

We're on (anniversary) travel, but found the doc here on the laptop:

In Figure 2, take a close look at the KX3's DC power input.  The DC to
DC converter shown eliminates whatever power impurities remain at this
end of the interior DC branch circuit.  Being a boost-buck regulator,
the converter can accept a wide range of input voltages and produces a
steady 13.8VDC (adjustable).  The converter used in this example
installation is made by QSKJ (model QS-1212CCBA-80W).  In addition to
cleaning up the DC, the converter reduces voltage sag from the smaller
gauge interior wiring.  In order to prevent the converter from
introducing its own emissions, a Laird LFB174095 ferrite core was used
with 3 turns of the KX3's stock cable.  This killed all converter
emissions.

See
http://ca.picclick.com/DC-DC-Converter-QS-1212CCBA-80W-Power-Supply-251036051706.html.

73,
matt

On Fri, 21 Sep 2012 16:24:43 -0700, you wrote:

>Any recommendation or specific brand or place to purchase one for a KX3. Appreciate the sharing of knowledge.
>
>Thanks,
>
>Keith
>AG6AZ
>
>Sent from my iPhone please excuse typos
>
>On Sep 21, 2012, at 4:19 PM, "Matt Zilmer" <mzilmer at verizon.net> wrote:
>
>> Yup.  All you have to do is stabilize the power supply at the K3.  I
>> recommend a DC-DC converter for this.
>> 
>> 73,
>> matt W6NIA
>> 
>> On Fri, 21 Sep 2012 14:22:26 -0700, you wrote:
>> 
>>> Matt 
>>> 
>>> That's exactly what has happened I saw the high current flash I didn't see it before because I was driving but I just saw it now so I think there's a positive correlation.
>>> 
>>> Thank you very much for the insight!
>>> 
>>> Keith
>>> AG6AZ
>>> 
>>> Sent from my iPhone please excuse typos
>>> 
>>> On Sep 21, 2012, at 7:18 AM, "Matt Zilmer" <mzilmer at verizon.net> wrote:
>>> 
>>>> The KX3 probably detected a HI CUR condition.  This can happen because
>>>> of high (or low) PS voltage due to automotive electrical fluctuations.
>>>> Sometimes this can happen because of ground current with the antenna
>>>> connected, so check this for a positive correlation.
>>>> 
>>>> You should not see HI CUR while on the KX3's internal batteries.  This
>>>> proves the automotive supply is caused it.
>>>> 
>>>> When the KX3 sees HI CUR (usually something higher than 300 mA on RX),
>>>> it will flash that HI CUR message on VFO A.  If the condition
>>>> persists, it will drop the AF gain to some predetermined value.  If
>>>> the condition continues beyond that point, the KX3 will shut itself
>>>> off to protect itself.  In my own case, both the AF gain and
>>>> self-shutdown events were happening.  HI CUR is preventable in a
>>>> mobile setting - see below.
>>>> 
>>>> I produced a pretty good document on KX3 mobile ops, which I'm about
>>>> to add to.  It's posted on the Elecraft web site at
>>>> http://www.elecraft.com/K2_Manual_Download_Page.htm#kx3_mobile.
>>>> 
>>>> Keith, I saw that same type of problem while mobile with KX3 #6 right
>>>> up until I installed a DC-DC converter.  See the doc for details of
>>>> all that.
>>>> 
>>>> 73,
>>>> matt W6NIA
>>>> KX3 #6, K3 #24, etc.
>>>> 
>>>> On Fri, 21 Sep 2012 05:45:18 -0700, you wrote:
>>>> 
>>>>> I had this happen to me during mobile operations and not sure why either. Signals dropped right out and then when I turned off the radio for a few minutes and when i turned on the KX3  it went back to where it was prior and remained that way.
>>>>> 
>>>>> I will keep an eye on it to see if it happens again. 
>>>>> 
>>>>> Keith
>>>>> AG6AZ
>>>>> 
>>>>> Sent from my iPhone please excuse typos
>>>>> 
>>>>> On Sep 20, 2012, at 7:43 PM, "Kevin Luxford" <elelist984 at elitemail.org> wrote:
>>>>> 
>>>>>> Hi Guys,
>>>>>> My KX3 has just developed an apparent fault - the audio level changes 
>>>>>> abruptly every few seconds from a comfortable listening level to quiet, 
>>>>>> but still audible.
>>>>>> 
>>>>>> I am using my Proset headphones.
>>>>>> 
>>>>>> Any thoughts on where I should start looking?  I am nervous about poking 
>>>>>> around surface mount circuits!
>>>>>> 
>>>>>> vy 73
>>>>>> Kevin
>>>>>> VK3DAP / ZL2DAP
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