Re: Voltages for Q5 and U8?

Posted by Don Wilhelm-4 on
URL: http://elecraft.85.s1.nabble.com/Voltages-for-Q5-and-U8-tp6825928p6826004.html

Mike,

I do not know where those DC voltages are listed.  For as long as the K1
has been out, I don't understand why that omission had not been spotted
long ago.

However, back to your problem - the quickest path to resolution is to go
first to page 5 of the manual troubleshooting appendix and build an RF
Probe (if you have a 'scope with a 10X probe, it can be used instead).  
The RF Probe does not have to be pretty, or shielded or anything like
that.  If necessary, punch the leads of the components through a piece
of cardboard to provide support, just connect the leads as indicated.

OK, RF Probe in hand, or 'scope (if using a 'scope, the Expected
voltages will be shown in peak to peak which are 2.8 times the RMS
voltages listed), go to the Transmit Signal Tracing section.  What you
are looking for is the first stage where the RF voltages are
significantly *lower* than the expected value.  If the voltages are
higher, that is OK, and is normal for a K1 that is not developing any RF
output.

Once you have identified the failing stage (the one where the output is
lower than expected, stop and let us know - we can help with detailed
analysis of that stage.

73,
Don W3FPR

On 9/23/2011 6:29 PM, K7MH wrote:

> I am troubleshooting a K1 that has no output.
> The guide says to check Q5 and U8 voltages but I do not find them listed
> anywhere.
> The DC voltages table lists U8 pin numbers but no voltages. I see nothing
> for Q5.
> If anyone knows what they are or where they are listed I would appreciate a
> reply.
> The receiver works ok and all the voltage and resistance measurements listed
> in the
> assembly part of the manual and those of U9 Q8 and Q7 are all good.
>
> Mike K7MH
>
> --
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