K2 doesn't work with mic connected

[Gary D Krause]

I thought I had a problem with the control board originally.  When I
turned on the K2 the "Elecraft" would come up and then go to the
frequency.  However, everything was frozen.  Nothing worked and the
frequency couldn't be changed.  I re-installed the control board, turned
it on and everything worked fine until I plugged in the mic.  Then
everything froze again.  Unplug the mic and everything comes back to
life.   I checked the jumpers for my mic configuration and they are
correct.  I'm using a Kenwood MC-60 mic with an internal preamp.  
However, I don't use the preamp but, I have the jumper installed for
it.  Any ideas?

Thanks,
Gary, N7HTS
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[Don Wilhelm-4]

Gary,

You seem to be having several problems that cannot logically be related
to each other.
I suggest that you re-check all your soldering.  Look at it with a
critical eye.  A good solder joint should have a concave fillet that
tapers off to an almost invisible edge on both the solder pad and the
component lead.  If your solder connections have a convex shape to them,
they have too much solder applied, and that alone can mask a bad solder
joint.  Unfortunately, the only cure is to wick away most of the solder
and reflow the remaining (perhaps adding a tiny bit of new flux and solder.
If your solder connections do have that 'rounded' convex appearance, the
most likely cause is that inadequate heat was applied to the solder pad
during the soldering process.  Use an iron temperature of 700 degrees F
or greater (I routinely use 750 degrees).

If when re-flowing the solder you see flux still boiling out of the
solder joint, that may mean again that not enough heat was used originally.

I cannot emphasize strongly enough - use adequate heat when soldering.  
The solder should flow within 2 to 3 seconds when the solder is applied
to a spot where the direct heat of the iron tip is *not* placed.  If it
takes longer than that, your iron is not hot enough.  Few components
will be damaged by a hot soldering iron applied for a short time (up to
5 seconds), but they can be damaged by a soldering temperature that is
too cold because things have to 'heat soak' for a long period to
properly flow the solder.  Normally 700 deg F. is enough, but some
boards like the KSB2 and the KPA100 have more extensive ground planes
and the copper area will wick away the heat more quickly, so a
temperature of 750 deg F or even 800 deg F is appropriate for these boards.

73,
Don W3FPR

Gary Krause wrote:

> I thought I had a problem with the control board originally.  When I
> turned on the K2 the "Elecraft" would come up and then go to the
> frequency.  However, everything was frozen.  Nothing worked and the
> frequency couldn't be changed.  I re-installed the control board,
> turned it on and everything worked fine until I plugged in the mic.  
> Then everything froze again.  Unplug the mic and everything comes back
> to life.   I checked the jumpers for my mic configuration and they are
> correct.  I'm using a Kenwood MC-60 mic with an internal preamp.  
> However, I don't use the preamp but, I have the jumper installed for
> it.  Any ideas?
>
> Thanks,
> Gary, N7HTS
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft   
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>

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[Darrell Bellerive-2]

Gary,

Is the frozen state possibly the K2 in transmit?

A ground on the PTT line will put the K2 into transmit and lock the frequency
display and disable most of the front panel controls with the exception of
the power control.

I had the similar problem with a stray strand of wire in the mic connector.
The problem appeared and disappeared with the movement of the mic cord at the
connector.

As the PTT line and dot line are common, connect a dummy load, turn the power
to minimum, remove the mic, set the mode to CW and then reconnect the mic. If
you get a sidetone when the mic is reconnected you know where the problem is.

On SSB, the PTT switch in the mic may be opening the mic's audio path, so the
rig will not have any power output. Checking on CW will isolate the problem.

Checking the mic connector with an ohmmeter might also find the PTT and Ground
shorted, unless like my mic, the problem was intermittent and dependant on
the position of the mic cord.

Darrell



On Friday 15 February 2008 20:00, Gary Krause wrote:

> I thought I had a problem with the control board originally.  When I
> turned on the K2 the "Elecraft" would come up and then go to the
> frequency.  However, everything was frozen.  Nothing worked and the
> frequency couldn't be changed.  I re-installed the control board, turned
> it on and everything worked fine until I plugged in the mic.  Then
> everything froze again.  Unplug the mic and everything comes back to
> life.   I checked the jumpers for my mic configuration and they are
> correct.  I'm using a Kenwood MC-60 mic with an internal preamp.
> However, I don't use the preamp but, I have the jumper installed for
> it.  Any ideas?
>
> Thanks,
> Gary, N7HTS
> _______________________________________________

--
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada
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