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K3 PA temp acting up

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Buck - k4ia

K3 PA temp acting up

Left the receiver on overnight and when I came down this morning I could
hear the fan running. That's odd. PA TEMP 45

If I turn off the power, the finals still heat up and when I turn the
power back on the HI TEMP warning activates, power is reduced and the PA
TEMP reads 105. Only way to cool it down is to unplug the power.

Any ideas?

--
Buck
k4ia
K3 # 101 KX3 #715
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N5GE

Re: K3 PA temp acting up

Howdy Buck,

The first thing that comes to mind is that a strait key has something
on top of it, but I sure you checked that. Is it possible that there
is a short in a keying circuit or maybe a foot switch that has
something on it or is shorted out while the rig is set in the CW
mode?

I don't think having either situation could cause transmit unless the
rig is in CW or data mode.

Is the TX LED lit up?

Good luck finding it...

73,
Tom
Amateur Radio Operator N5GE
ARRL Lifetime Member
QCWA Lifetime Member

On Sat, 27 Apr 2013 19:11:17 -0400, Buck k4ia <[hidden email]> wrote:

>Left the receiver on overnight and when I came down this morning I could
>hear the fan running. That's odd. PA TEMP 45
>
>If I turn off the power, the finals still heat up and when I turn the
>power back on the HI TEMP warning activates, power is reduced and the PA
>TEMP reads 105. Only way to cool it down is to unplug the power.
>
>Any ideas?

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Amateur Radio Operator N5GE

Don Wilhelm-4

Re: K3 PA temp acting up

In reply to this post by Buck - k4ia

Buck,
If indeed the finals are heating while the K3 is truly in receive mode,
then that would indicate either the PA finals have 'turned belly up' or
that there is a failure in the bias circuits that is turning the PA
transistors on.
First unplug everything from the K3 except for a dummy load. Then plug
it in and see if it still draws PA current
If you have the same problem with everything unplugged, an email to
K3support is in order (or a phone call after they wake up and have their
morning beverage Monday morning.

73,
Don W3FPR

On 4/27/2013 7:11 PM, Buck k4ia wrote:

> Left the receiver on overnight and when I came down this morning I
> could hear the fan running. That's odd. PA TEMP 45
>
> If I turn off the power, the finals still heat up and when I turn the
> power back on the HI TEMP warning activates, power is reduced and the
> PA TEMP reads 105. Only way to cool it down is to unplug the power.
>
> Any ideas?
>
>

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Buck - k4ia

Re: K3 PA temp acting up

Don - thanks

If I let it sit while turned on, the fan will bring the temp down, then
I can turn the power back up and operate at 100w. The fans keep the PA
temp around 45C. So I don't think the finals have gone - yet.

It is drawing about 2 amps with the power turned off but plugged in and
a little under 4 amps in receive when turned on.

I was biased toward the bias but don't understand why it is drawing 2
amps of current while turned off.

I have not installed the gold connector mod yet. KPA3CONMDKT Any
chance the problem is there?

Buck
k4ia
K3 # 101 KX3 #715

On 4/27/2013 7:56 PM, Don Wilhelm wrote:

> Buck,
> If indeed the finals are heating while the K3 is truly in receive mode,
> then that would indicate either the PA finals have 'turned belly up' or
> that there is a failure in the bias circuits that is turning the PA
> transistors on.
> First unplug everything from the K3 except for a dummy load. Then plug
> it in and see if it still draws PA current
> If you have the same problem with everything unplugged, an email to
> K3support is in order (or a phone call after they wake up and have their
> morning beverage Monday morning.
>
> 73,
> Don W3FPR
>
> On 4/27/2013 7:11 PM, Buck k4ia wrote:
>> Left the receiver on overnight and when I came down this morning I
>> could hear the fan running. That's odd. PA TEMP 45
>>
>> If I turn off the power, the finals still heat up and when I turn the
>> power back on the HI TEMP warning activates, power is reduced and the
>> PA TEMP reads 105. Only way to cool it down is to unplug the power.
>>
>> Any ideas?
>>
>>
>

Buck - k4ia

Re: K3 PA temp acting up

In reply to this post by N5GE

Thanks for the try Tom. No it is not transmitting. In fact, it is even
weirder than that, the finals heat up while the radio is turned off. It
draws 2 amps when off.

Buck
k4ia
K3 # 101 KX3 #715

On 4/27/2013 7:43 PM, Tom H Childers wrote:

> Howdy Buck,
>
> The first thing that comes to mind is that a strait key has something
> on top of it, but I sure you checked that. Is it possible that there
> is a short in a keying circuit or maybe a foot switch that has
> something on it or is shorted out while the rig is set in the CW
> mode?
>
> I don't think having either situation could cause transmit unless the
> rig is in CW or data mode.
>
> Is the TX LED lit up?
>
> Good luck finding it...
>
> 73,
> Tom
> Amateur Radio Operator N5GE
> ARRL Lifetime Member
> QCWA Lifetime Member
>
> On Sat, 27 Apr 2013 19:11:17 -0400, Buck k4ia <[hidden email]> wrote:
>
>> Left the receiver on overnight and when I came down this morning I could
>> hear the fan running. That's odd. PA TEMP 45
>>
>> If I turn off the power, the finals still heat up and when I turn the
>> power back on the HI TEMP warning activates, power is reduced and the PA
>> TEMP reads 105. Only way to cool it down is to unplug the power.
>>
>> Any ideas?
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>