K2/100 Shuts Power Down

[Patrick DalPorto-2]

The K2/100 has been working very well for a couple of years but it has developed a problem.  I was on 15 m. SSB and made a quick call and the rig made a noise, shut down, and restarted.  It had shifted frequency and the fan was running when it came back on.  I readusted the tPA.  When I try to tune the radio at low power it tunes but will shut down very shortly.  
I thought I may have a bad diode in the SWR bridge but D16 and D17 seem to be fine when checked in the circuit.  Is it necessary to remove them from the circuit board to check them properly?

Anyone have any clues where I can start looking for the trouble.  I have put the low power top and tuner back on the rig and it works just fine.  I also tried the KAT100 and another tuner and the result is the same.

73,
Pat W8FV/5H9PD
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[N8LP]

Just a total shot in the dark... but what is your SWR like on 15? It
could be stray RF causing your power supply to shut down. I would check
my grounds, and also maybe a different supply, or battery if you have
one that will handle the power.

Larry N8LP



Patrick DalPorto wrote:

> The K2/100 has been working very well for a couple of years but it has developed a problem.  I was on 15 m. SSB and made a quick call and the rig made a noise, shut down, and restarted.  It had shifted frequency and the fan was running when it came back on.  I readusted the tPA.  When I try to tune the radio at low power it tunes but will shut down very shortly.  
> I thought I may have a bad diode in the SWR bridge but D16 and D17 seem to be fine when checked in the circuit.  Is it necessary to remove them from the circuit board to check them properly?
>
> Anyone have any clues where I can start looking for the trouble.  I have put the low power top and tuner back on the rig and it works just fine.  I also tried the KAT100 and another tuner and the result is the same.
>
> 73,
> Pat W8FV/5H9PD
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>  

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[Kevin Rock]

Sounds like a problem I have had.  The power just folds for some reason.  
Well, I fixed it, but the problem is not what you may expect.  My K2/100,  
SN #2511, has been working fine for years but it, too, experienced this  
problem starting a few months ago.  I thought it was the power supply so I  
tried my battery power.  This worked for a while.  So I tried another  
power supply.  This too worked for a short while but the problem  
recurred.  A friend said look at the Anderson PP connectors and see if  
there is a loose connection or corrosion.  So, I made and broke the  
connection between both ends of the cables multiple times to wipe the  
silver connectors clean.  This worked for a while but the problem came  
back.  What did fix the problem for more than just a short period of time  
was to hang my power cable from hooks to take the strain off the  
connectors.  The weight of the cable was pulling on the connections  
creating an intermittent fault.  When the K2/100 warmed up enough the  
power connection would fail, the rig would emit some odd noises, power  
cycle, and I'd not be able to transmit at full power.  After hanging the  
cable this has not occurred again in twenty or more hours on the air.  Now  
I can run from either my batteries or from a power supply at 100 watts  
with no difficulty for an hour or more of CW.
    Good luck,
       Kevin.   KD5ONS


On Sun, 19 Nov 2006 20:21:45 -0800, Patrick DalPorto <[hidden email]>  
wrote:

> The K2/100 has been working very well for a couple of years but it has  
> developed a problem.  I was on 15 m. SSB and made a quick call and the  
> rig made a noise, shut down, and restarted.  It had shifted frequency  
> and the fan was running when it came back on.  I readusted the tPA.  
> When I try to tune the radio at low power it tunes but will shut down  
> very shortly.
> I thought I may have a bad diode in the SWR bridge but D16 and D17 seem  
> to be fine when checked in the circuit.  Is it necessary to remove them  
> from the circuit board to check them properly?
>
> Anyone have any clues where I can start looking for the trouble.  I have  
> put the low power top and tuner back on the rig and it works just fine.  
> I also tried the KAT100 and another tuner and the result is the same.
>
> 73,
> Pat W8FV/5H9PD

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[Don Wilhelm-3]

Kevin,

I would speculate that you have a break in your cable near the APP connector
rather than a failure of the APP connector itself.

This is a result of cable flexing with soldered connectors.  The wire will
break at whatever point the solder has wicked back onto the cable.  If you
flex the cable, you can feel where the stiff part ends and the cable becomes
flexible - in my experience this will occur about an inch from the APP
connector.

Of course this is one good vote for crimped APP connections rather than
soldered, but I still prefer to solder mine.  Beware of this potential
problem and if it occurs, cut off about 1 inch of the cable and re-solder to
the APP connector.  A small knife blade or sharp flat-blade screwdriver can
be used to remove the insert from the APP connector - just pry up the
contact a bit and it should side out of the housing.

73,
Don W3FPR

> -----Original Message-----
>
> Sounds like a problem I have had.  The power just folds for some
> reason.
> Well, I fixed it, but the problem is not what you may expect.  My
> K2/100,
> SN #2511, has been working fine for years but it, too, experienced this
> problem starting a few months ago.  I thought it was the power
> supply so I
> tried my battery power.  This worked for a while.  So I tried another
> power supply.  This too worked for a short while but the problem
> recurred.  A friend said look at the Anderson PP connectors and see if
> there is a loose connection or corrosion.  So, I made and broke the
> connection between both ends of the cables multiple times to wipe the
> silver connectors clean.  This worked for a while but the problem came
> back.  What did fix the problem for more than just a short period
> of time
> was to hang my power cable from hooks to take the strain off the
> connectors.  The weight of the cable was pulling on the connections
> creating an intermittent fault.  When the K2/100 warmed up enough the
> power connection would fail, the rig would emit some odd noises, power
> cycle, and I'd not be able to transmit at full power.  After hanging the
> cable this has not occurred again in twenty or more hours on the
> air.  Now
> I can run from either my batteries or from a power supply at 100 watts
> with no difficulty for an hour or more of CW.
>     Good luck,
>        Kevin.   KD5ONS
>

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[Ron D'Eau Claire-2]

In addition to the other good comments here, check your in-line fuse to the
KPA100. I've had those small cartridge-type fuses develop an intermittent
after being a period of time. Sometimes its just a bad contact where it
presses against the contacts in the holder, other times one of the
connections between the fuse wire and the end contact opens inside the fuse.
Very often the bad connection is highly temperature-sensitive so everything
will seem okay for a while then suddenly it opens briefly until it cools
again, then everything looks okay until you draw significant current again.


Ron AC7AC

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