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Re: k2 low output solution.

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Pat n8vw

Re: k2 low output solution.

On 4 Aug 2005 22:40:19 -0400, "Pat N8VW" <[hidden email]> wrote :

> My K2 (2016) is suffering low output starting on 20 and wrapping around to
> 10 and 160 where I get little to no output. 80,40,30 are unaffected. Rx is
> great. Symptoms include, low output and inability to increase output beyond
> a certain level. Both symptons vary per band. When I'm less tired I'll
> produce some data.
>
> It sounds like something in the vpwr circuit. I checked the voltages on U8
> and found pin 10 had 5v and 11 had 0v which is opposite of what it is in the
> manual.
>
> Thoughts anyone?
>

After some more debugging it appears that the ksb2 is causing the problem.
Removing it returns tx power to normal levels. Some might say, good you
don't need ssb anyway.

Looking at the dac u2 I find that pin 5 is at 6v when it should be ~.6v on
tx and rx. Removing Q1 makes no difference so it appears that u2 is the
problem.

Any thoughts on this?

Pat N8VW

> Pat N8VW
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Mike Harris-9

Re: k2 low output solution.

G'day,

> After some more debugging it appears that the ksb2 is causing the
problem.
> Removing it returns tx power to normal levels. Some might say, good
you
> don't need ssb anyway.

Sounds somehow familiar. Check the resistor packs.

Regards,

Mike VP8NO

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Matt Osborn

Re: k2 low output solution.

In reply to this post by Pat n8vw

Hi Pat,

There are three two signals fed into the KSB2 that directly affect
power output. One is V RFDET which controls the base of Q1 and the
other is ALC which is applied to the collector of Q1. Since removing
Q1 makes no difference, V RFDET isn't likely the cause. But the ALC
on the collector of Q1 remains in play.

V RFDET has three sources, D9 on the K2 RF board, the SWR bridge on
the KAT2 and the XVTR ALC on the K60XV option.

The ALC signal comes from the KAP100 (or other external power
amplifier) and is fed back through the KIO2 to the K2 control board's
AUX IO P4 and then sent on to pin 9 of J11 which is fed to the KSB2.

Since V RFDET and ALC are both derived from actual power measurements,
they are more likely to cause power problems that are band related.

Disconnecting the KIO2 (and KAT2 if installed) should be an easy test.

On 5 Aug 2005 23:04:11 -0400, "Pat N8VW" <[hidden email]> wrote:

>
>On 4 Aug 2005 22:40:19 -0400, "Pat N8VW" <[hidden email]> wrote :
>
>> My K2 (2016) is suffering low output starting on 20 and wrapping around to
>> 10 and 160 where I get little to no output. 80,40,30 are unaffected. Rx is
>> great. Symptoms include, low output and inability to increase output beyond
>> a certain level. Both symptons vary per band. When I'm less tired I'll
>> produce some data.
>>
>> It sounds like something in the vpwr circuit. I checked the voltages on U8
>> and found pin 10 had 5v and 11 had 0v which is opposite of what it is in the
>> manual.
>>
>> Thoughts anyone?
>>
>
>After some more debugging it appears that the ksb2 is causing the problem.
>Removing it returns tx power to normal levels. Some might say, good you
>don't need ssb anyway.
>
>Looking at the dac u2 I find that pin 5 is at 6v when it should be ~.6v on
>tx and rx. Removing Q1 makes no difference so it appears that u2 is the
>problem.
>
>Any thoughts on this?
>
>Pat N8VW
>
>
>
>
>> Pat N8VW
>> _______________________________________________
>> 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
>>
>>
>>
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
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>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com