[Elecraft] K3: KPA100 Squeal

Fri Jul 1 05:49:42 EDT 2011

I just listened to Geoff's recording, and this is exactly what is happening
with my K3/100.

On Fri, Jul 1, 2011 at 1:49 AM, Geoff Wolf AB3LS <liltechdude13 at gmail.com>wrote:

> No go.
>
> Hooked the radio up to a gel cel battery and we're still getting the 12Khz
> junk coming from something and the clicking between TX and RX.
>
> I made a longer recording of the 'junk' and posted it. Cycled between TX
> and
> RX a few times using the manual TX button on the front. Then finished off
> with a few dits and dahs. All while in TX Test mode.
>
>
> http://alien.liltechdude.com/files/index.php?dir=Recordings/&file=kpa3squealrev2.mp3
>
> Anyone from Elecraft have anything on this?
>
> AB3LS
>
> On Fri, Jul 1, 2011 at 1:24 AM, Geoff Wolf AB3LS <liltechdude13 at gmail.com
> >wrote:
>
> > This is a brand new K3 that I assembled about a month ago. The Serial
> > Number is 5517.
> >
> > I have been using an Astron SS-25A power supply with this which is indeed
> a
> > switcher. I have a battery that I'll be hooking up to it to see if this
> is
> > still a problem.
> >
> >
> > On Thu, Jun 30, 2011 at 4:41 PM, Guy Olinger K2AV <olinger at bellsouth.net
> >wrote:
> >
> >> A repeated 12 kHz would be echoed all over the room and lose a lot of
> >> it's pulse nature.  This continues to look suspiciously like crap from
> >> a 12 volt switching power supply that is somehow finding something
> >> mechanically resonant in the K3.
> >>
> >> Back to asking for 12 volts from a linear supply (transformer and 60
> >> Hz rectifiers) or battery.
> >>
> >> Is this particular K3 serial # prior to the introduction of gold
> >> plated pins for the KPAIO3 connection?
> >>
> >> 73, Guy.
> >>
> >> On Thu, Jun 30, 2011 at 1:52 PM, W5UXH <Chuck.Broadwell at gmail.com>
> wrote:
> >> > I looked at the MP3 file using Goldwave.  It appears to me that the
> "12
> >> KHz"
> >> > component is present only during the tics, not continuously.
> >> >
> >> > The tic period is roughly 270 msec (I have no idea what the tic is of
> >> > course).   I zoomed in to a single tic (see PDF of images at the link
> >> > below).  It appears that each tic has a very distinct pattern seen in
> >> the
> >> > individual samples which I suspect is the 12 KHz energy.
> >> >
> >> > I have no idea what any of this means.
> >> >
> >> > 73,
> >> >
> >> > Chuck, W5UXH
> >> > Las Cruces, NM
> >> >
> >> >
> >>
> https://sites.google.com/site/k3lineoutrecordings/ab3ls-mp3-file-analysis
> >> > Images and comments from Goldwave view of the MP3 file
> >> >
> >> >
> >> > Guy, K2AV wrote:
> >> >>
> >> >> Hi Geoff, below...
> >> >>
> >> >> On Thu, Jun 30, 2011 at 9:24 AM, Geoff Wolf AB3LS
> >> >> &lt;liltechdude13 at gmail.com&gt; wrote:
> >> >>> And, for even more information, I analyzed the audio that I recorded
> >> and
> >> >>> the
> >> >>> squeal is right around 12Khz. It peaks at -48dB (louder than the QSK
> >> >>> relay
> >> >>> clicking)
> >> >>>
> >> >>> http://imgur.com/V8o5t - image of the analysis
> >> >>>
> >> >>> AB3LS
> >> >>
> >> >> With your image I realize I had been making some assumptions.  I need
> >> >> to fill in some details...
> >> >>
> >> >> Are you listening to the audio in earphones or are you hearing it in
> >> >> the free air.  I had been assuming listening with your ears only in
> >> >> free air to miscellaneous sound in the neighborhood of the K3.
> >> >>
> >> >
> >> >
> >> > --
> >> > View this message in context:
> >>
> http://elecraft.365791.n2.nabble.com/K3-KPA100-Squeal-tp6518460p6534295.html
> >> > Sent from the Elecraft mailing list archive at Nabble.com.
> >> > ______________________________________________________________
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-- 
Joe Harris, N1QD