[Elecraft] KAT100 signal question

BobConvers at aol.com BobConvers at aol.com
Sat Jul 23 18:10:21 EDT 2005


>>To put it another way, what _is_ working?>>

Sorry, I had not repeated information from an earlier post:   I have proceded 
in constructing the KAT100 as far as the step of connecting the KAT100 to the 
K2/KPA100, on the K2 panel switching back and forth between ANT1 and ANT2, 
looking for proper illumination of the tuner LEDs, and listening for operation 
of the tuner relays.   The K2 menu includes an ATU entry, with proper submenu 
entries (AUTO, L1, C1, etc) which I interpreted to mean that the K2 was 
recognizing the presence of the tuner.   The tuner LEDs correctly indicate operation 
of K2 controls (ANT1/2 and HI/tuner relay action from ANT1/ANT2, power adjust, 
K2 ATU menu operation, or anything else.

>>
>>A voltage of 2.25 voltswould indicate that it is very rapidly changing and 
your VOM is 
averaging it to that level, or something is incorrectly connected on 
the board. Again, maybe a bad solder joint, not soldered at all, OR, 
a solder splash causing a short from the RYLOAD line to a signal that 
is normally high (even +5V).
        ......
The evidence is getting stronger for a short between two 
conductors on the board. It is possible that one of the ICs is 
internally shorted causing the problem, but it is more likely that 
the problem is external to the chips. Go back and inspect the board 
with a good magnifying glass, and you might check your solder joints. >>

I had carefully inspected the board with Optivisor, but will check again for 
splashes.   All solder joints look shiny, but I'll re-heat any joints that are 
in the path of signals we are looking at.

>>
>>Also, check the MCU (U1) to make sure that all pins are in the socket 
and that none got bent under when installing the chip. Bending pins 
when inserting chips into sockets is way too easy to do, especially 
for 40 pin devices. A bent pin could be shorting against another pin, 
causing conditions similar to what you described.>>

Using the magnifier, the MPU pins look even and properly inserted.   I had 
considered lifting the MPU out of its socket for a closer look, but thought that 
might cause more problems than it would reveal.    I'll do it now.

Thanks again, and I will let you know if I find anything.

73,
Bob, WO3E




More information about the Elecraft mailing list