Cal tPA trouble

[Les Preston]

Hi there,

I have just got around to building my KPA100 (to Appendix G - Rev. C-5) for
my K2 (53 * * ), and thought that you may be interested in hearing about one
problem which I encountered during the build.  When I went to CAL tPA, I
found that the temperature reading was 'stuck' on 0 degrees C and wouldn't
move for love nor money!  Anyway, I checked the circuit through and was
convinced that I had a corrupted U1 Microcontroller, and was just about to
call it a day and order a replacement when, with a frantic to and fro on the
tuning dial, the digits suddenly re-appeared!!  CAL tPA was then carried
out!  I just wondered if anyone else had come across this and what is/was
the cure?, as I don't recall seeing anything in the archives, except for a
similar problem, but being 'stuck' on the number 255.

73,
Les  M0BSI

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[Don Wilhelm-3]

Les,

You may be wise to check the soldering on your KPA100 - it sounds like you
may have an unsoldered connection.  Check particularly around U1, R5, R6,
and Q3.

73,
Don W3FPR

> -----Original Message-----
>
> Hi there,
>
> I have just got around to building my KPA100 (to Appendix G -
> Rev. C-5) for
> my K2 (53 * * ), and thought that you may be interested in
> hearing about one
> problem which I encountered during the build.  When I went to CAL tPA, I
> found that the temperature reading was 'stuck' on 0 degrees C and
> wouldn't
> move for love nor money!  Anyway, I checked the circuit through and was
> convinced that I had a corrupted U1 Microcontroller, and was just
> about to
> call it a day and order a replacement when, with a frantic to and
> fro on the
> tuning dial, the digits suddenly re-appeared!!  CAL tPA was then carried
> out!  I just wondered if anyone else had come across this and what is/was
> the cure?, as I don't recall seeing anything in the archives,
> except for a
> similar problem, but being 'stuck' on the number 255.
>
> 73,
> Les  M0BSI
>

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[Les Preston]

Hi Don,

I checked my soldering around the areas suggested but I cannot see anything
untoward, and CAL tPA is still behaving itself so, I guess that if there is
a problem there, it will show up in time!  I was more concerned with the
fact that I couldn't adjust the setting from 0 degrees C really.
Many thanks for your help.

73,

Les M0BSI

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