Q3 is probably not your problem. It is an open-drain switch that
inverts the 8R signal, conditioning it for the microcontroller. It
appears that the MCU provides the pullup for the signal through the
internal pullup on PB6. 4.99 volts is about right for this signal.
Just what is the "relay problem" you are seeing? If Q3 and the /8R
signals were bad, the KAT would not switch to transmit conditions at
all. This would be indicated in a number of ways, such as not even
trying to tune. Relay troubles, however, could be isolated to a small
area in the circuit.
On Jul 23, 2005, at 10:37 AM, [EMAIL PROTECTED] wrote:
In troubleshooting a relay problem on my KAT100, Gary advised me to
check the
signal /8R, generated by Q3. I think Q3 may be faulty, since
(using a Fluke
DMM) signal /8R alternates between zero and only 4.99v as the
KPA100 is
cycled between receive and TUNE. Signal 8R alternates between
7.91v and zero, as
I would expect.
Before, I disassemble, de-solder, and install a new Q3, however, could
someone verify that 4.99 v is indeed lower than it should be and Q3
is probably bad.
Thanks.
73,
Bob, WO3E
_______________________________________________
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
- Jack Brindle, W6FB
------------------------------------------------------------------------
---------------------
_______________________________________________
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
