[Elecraft] KIO2 Malfunction

[Don Wilhelm]

Larry,

First remove any connector from the DB9 that may be plugged in and 
re-check the voltage at U1 pin 8.

You should not assume that U1 is the culprit (but it may be).  Even 
though the DC voltages at Q1 may be OK, it could be producing less 
oscillation than normal because of a faulty crystal or a faulty Q1.  D4 
could be leaky which would cause the RF voltage level to be less than 
normal. (the only function this oscillator has is to provide an RF 
source that can be rectified for the negative voltage).

You could be correct that U1 is to blame, and if you have good 
desoldering tools, the best check is to remove it and see if the voltage 
at D1 anode increases significantly.

If you decide to replace U1 anyway, even by cutting its pins, do check 
the voltage at D1 anode before putting the chip back in.
In the KIO2, about the only source of damage to the MAX1406 chip comes 
from outside the K2 - you might be wise to check your adapter before 
plugging in a computer connection.

73,
Don W3FPR

KT4G wrote:
> Hello all,
>
> I'm having problems with my KIO2.  The unit was functioning normally until
> recently, then suddenly failed to connect to my PC.
>
> I pulled the unit, set the rig to the settings recommended in the manual,
> and measured the following voltages:
>
> U1: All voltages within normal range EXCEPT:
> Pin 5   -0.03 (-8.0 is normal)
> Pin 8   -3.4 (-9.0 is normal)
>
> J1: All voltages within normal range EXCEPT:
> Pin 2   -0.02 (-8.0 is normal)
> Pin 4   6.0 (4.5 is normal)
>
> J2: All voltages within normal range EXCEPT:
> Pin 7   6.0 (4.5 is normal)
>
> Diodes:
> D1A   -3.3 (-9.0 is normal)
> D1C   0.0 (0.1 is normal)
> D2A   -3.3 (-4.0 is normal)
> D2C   -1.9 (0.1 is normal)
> D2A   -1.9 (-4.0 is normal)
> D2C   0.0 (0.0 is normal)
>
> Oscillator is normal.
>
> I highly suspect U1 (MAX1406) is the culprit, since I'm getting the proper
> voltages from U2 and Q1.  
>