[Elecraft] KAT100 signal question

[W3FPR - Don Wilhelm]

Bob,

I don't have a KAT100 here to check it, but I can say that how much RYDATA
wiggles up and down will depend on what the microprocessor is trying to
initially set the relays to - if it happens to be all '1s' the line may
always be high during the setting time frame.  That data is locked into the
shift resisters, so the uP only has to update the settings occasionally.  I
would expect the front panel data to be updated more frequently and
monitoring the FPDATA line is much more likely to show activity.

Sorry I can't help more without having it in my hands.  Perhaps Gary can
help when he returns to work on Monday.

73,
Don W3FPR

> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net]On Behalf Of BobConvers at aol.com
> Sent: Saturday, July 23, 2005 2:43 PM
> To: w3fpr at arrl.net; elecraft at mailman.qth.net
> Subject: Re: [Elecraft] KAT100 signal question
>
>
> Thanks, Don.   Actually, I get NO action from ANY relay, although
> the LEDs
> are switching correctly.   I tried to check the signal RYDATA (as
> best I could
> with no scope, only DMM) and it is an absolutely constant level.
>  The front
> panel signal FPDATA jumps around in value as the signals come through to
> activate the LEDs, but RYDATA is dead still.   There is 12 v on
> the the hot side of
> the relays and 5 volts on pins 2 of U2, U3, and U4.   With power removed,
> RYDATA measures over 5 megs to ground.   Any other suggestions?
>
> 73,
> Bob, WO3E
>
>
> >>>>
>  Bob,
>
> I would think Q3 is OK since it simply acts as a switch - it does not
> produce any voltage.  The MCU (U1) pin 39 is the source for voltage on the
> drain of Q3, and a high level of somewhere near 5 volts is to be expected.
>
> Look somewhere else for the problem.  It is difficult to see directly
> whether the microprocessor is creating the correct output because
> it is fed
> to the relay drivers as serial data, but the relay driver pins should have
> the outputs for the selected relays at a low level, and go to
> about 12 volts
> on the pins connected to the unselected relays.  Check the
> schematic sheet 1
> to see which pins correspond to which relays.
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