[Elecraft] KPA100 problem / Update

[n0jrn]

OK,    my new MAX1406's came in today.

I really made a point to check out every possible cause for the previous 
chip issues.

Installed the new MAX1406 and now have 122.1 V's at the junction of C77 and 
R11.       Also have a -22.4 V's at pin 8 of U4.

So,   the new chip fixed this issue............

Now to move on to the next challenge.

Thanks to everybody for your suggestions and support.

73    Jerry            N0JRN
----- Original Message ----- 
From: "Don Wilhelm" <don at w3fpr.com>
To: "n0jrn" <n0jrn at mchsi.com>
Sent: Monday, December 14, 2009 6:22 AM
Subject: Re: [Elecraft] KPA100 problem


> Jerry,
>
> I will take back what I said about U4 - it is faulty.
> That negative voltage is there only to allow the RS-232 drivers to produce 
> a negative level, the current draw should be minimal.
> The only thing U4 does is convert RS-232 levels to TTL levels and 
> vice-versa.