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KAT2 question abt voltage at U4, pin7

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KC9GBX

KAT2 question abt voltage at U4, pin7

After a recent calamity while attempting PSK31, where I introduced 13.5v into microphone jack pin 6 (a 5v line), repairs have been made, and I have made contacts in both cw and ssb modes.

However, I seem to be getting more HI CURRENT warnings on bands and at power levels where previously, I did not.

I re-initialized the KAT2, and, as I cycle through L0-L8 and C0-C8, all relays provide a nice click.

I performed the dc voltage checks at the bottom of KAT2 manual, page 22. Everything was fine, except for U4, pin 7 where I got a reading of 4.74v instead of the 0v or nearly 0v that the manual implies I should see. Could this be the cause of the HI CURRENT warnings?

Thanks for your consideration. 73, Jef Fox kc9gbx

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Don Wilhelm-4

Re: KAT2 question abt voltage at U4, pin7

Check the actual power with an external wattmeter - set the power
control to 5 watts and transmit, then tell us if the actual power is
near 5 watts or near the maximum power (12 watts or over).

It is possible that U4 is faulty. Pin 7 is not used - there are 2 op
amps in the LM358 package, so if the one having its output at pin 1 is
OK, power will be controlled and it does not matter what pin 7 does
because it is connected to nothing. The power output check above will
tell if the output at U4 pin 1 is working.

73,
Don W3FPR

[hidden email] wrote:

> After a recent calamity while attempting PSK31, where I introduced
> 13.5v into microphone jack pin 6 (a 5v line), repairs have been made,
> and I have made contacts in both cw and ssb modes.
>
> However, I seem to be getting more HI CURRENT warnings on bands and at
> power levels where previously, I did not.
>
> I re-initialized the KAT2, and, as I cycle through L0-L8 and C0-C8,
> all relays provide a nice click.
>
> I performed the dc voltage checks at the bottom of KAT2 manual, page
> 22. Everything was fine, except for U4, pin 7 where I got a reading
> of 4.74v instead of the 0v or nearly 0v that the manual implies I
> should see. Could this be the cause of the HI CURRENT warnings?
>
> Thanks for your
> consideration. 73,
> Jef Fox kc9gbx
>
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