[Elecraft] KPA100 Help PLEASE

[Pete Meier]

Thanks to Lyle and Ned I have found my problem. It was a lifted land 
between RP1 P5 and U1 Pin 7 on the underside of the PA board.  No other 
component problems were discovered. Voltages and resistances are all 
nominal so I'm not sure what caused the break in the land. It was right 
at a open feed through hole. All appears normal now. So on the next 
section of test and alignment.

Thank again guys for the quick help.

Pete WK8S

On Thursday, December 26, 2002, at 12:31  PM, Ned Asam wrote:

> Peter,
>
> Good, you are making progress.
>
> My next suggestion is the same as Lyle's. Check the voltages around  
> Q12. This is an FET  switch which is off when the 12 PA is missing. If 
> this FET switch is off, the voltage at pin 7 of U1 will be 0 -- if on, 
> expect a positive 6 + volts at pin 7. Check the voltage levels all 
> around Q12.
>
> Good Luck...
>
> ...Ned, KC2FLM
>
> [Elecraft] KPA100 Help PLEASE
>
> Lyle Johnson wa7gxd@fidalgo.net
> Thu Dec 26 11:37:01 2002
>
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>
>
>
> > I have completed the KPA100 upgrade but cannot get the K2 to 
> recognize
> > it. With a 20 amp supply connected I still get NO PA PS.
>
>
> Check and verify that you have between about 3V and not more than 6V 
> at U1
> pin 7.  This senses the presence of the "12PA" source and is most 
> likely
> what the KPA100 CPU uses to verify there is a power supply attached and
> working.  See Sheet 2 of the schematic,  in the upper left.  R8, Q12, 
> RP1.
> You should see about +12 on the 12PA side of R8, About +4 on the 
> source and
> drain of Q12, and about +12 on the gate of Q12.
>
> 73,
>
> Lyle KK7P
>
>
>
>
> At 11:11 AM 12/26/2002 -0500, you wrote:
>> Hi Ned,
>>
>> I am only using the high current connection. I have no problem with 
>> low power xmit/receive on any band. I am getting about 120 volts at 
>> R11, R12.
>>
>> Pete
>>
>>
>> On Thursday, December 26, 2002, at 10:34  AM, Ned Asam wrote:
>>
>>> Peter,
>>>
>>> It sounds like you almost working, since all the low power circuits 
>>> seem to be working. I assume the LP filter  relays on the KPA 100 
>>> are also working. That is, you can transmit and receive at low power 
>>> on all bands. All these circuits are powered from the low power 
>>> source on the base K2.
>>>
>>> What happens when you disconnect the low power 12 volts, and the 
>>> high power 12 v is still connected? If all is off, then this would 
>>> also point to the High Power 12 volt path.
>>>
>>> If I understand the situation correctly, I would trace the high 
>>> power 12 volts from the back of the unit through the amplifier 
>>> section -- r13, c75, rfc1 and so on...
>>>
>>> Are you getting the 90 to 150 volts at R11 and R12? This is 
>>> generated on the KPA from the high power 12 volt source. If not, 
>>> check all around T3 for good solder connections.etc...
>>>
>>> Regards,
>>>
>>> Ned, KC2FLM
>>
>