K1 RF board DC checks failing

[Mike Clarke-3]

Hi all,

Having received and fitted the replacement voltage regulator that
solved my previous K1 problem, I've moved on to the first DC checks on
the RF board (page 30 in my manual.)

I'm performing the checks with the board connected to a stable supply
at 13.8 volts.

The first two checks pass fine, but the second two state that I should
be reading between 3.8 and 4.2 volts on U3 pin 5, and between 7.6 and
8.7 volts on U3 pin 6.  I'm actually measuring 3.66 volts and 7.54
volts, respectively.

Normally these might count as 'close enough', but given the quality of
the manual (and my soldering!) I'm inclined to think I've gone wrong
somewhere!  Can anyone offer a suggestion as to what I might have
done?

Thanks and 73,

--
Mike, M0PRL.
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[Don Wilhelm-4]

Mike,

U3 pin 6 is the output voltage of the 8 volt regulator - it is lower
than usual, but not in excess of the regulator specs (+/-10%).  Pin 5 is
an output from U3 and will depend on the voltage applied to pin 6.
So bottom line - all is OK.

73,
Don W3FPR

Mike Clarke wrote:

> Hi all,
>
> Having received and fitted the replacement voltage regulator that
> solved my previous K1 problem, I've moved on to the first DC checks on
> the RF board (page 30 in my manual.)
>
> I'm performing the checks with the board connected to a stable supply
> at 13.8 volts.
>
> The first two checks pass fine, but the second two state that I should
> be reading between 3.8 and 4.2 volts on U3 pin 5, and between 7.6 and
> 8.7 volts on U3 pin 6.  I'm actually measuring 3.66 volts and 7.54
> volts, respectively.
>
> Normally these might count as 'close enough', but given the quality of
> the manual (and my soldering!) I'm inclined to think I've gone wrong
> somewhere!  Can anyone offer a suggestion as to what I might have
> done?
>  
>

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[Mike Clarke-3]

On Mon, May 18, 2009 at 2:49 PM, Don Wilhelm <[hidden email]> wrote:
> Mike,
>
> U3 pin 6 is the output voltage of the 8 volt regulator - it is lower than
> usual, but not in excess of the regulator specs (+/-10%).  Pin 5 is an
> output from U3 and will depend on the voltage applied to pin 6.
> So bottom line - all is OK.

Hi Don,

Thanks for the response to what must seem like a trivial question to old hands!

It's good to know I'm not ignoring things now and saving trouble up for
when it's more difficult to debug :)

73,

--
Mike, M0PRL
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