My work with a friend's LK550 is making forward progress (quick catch-up - the
amplifier has had a history of faults and repair attempts that converge back on
ALO/Meter board - now disabled - and QSK board.)
ALO/Meter board has now been de-powered (disconnect 12V from XMT/STBY switch to
J1 DC input pin), taking the "overload" aspects of the ALO/Meter board out of
operation, just leaving the basic passive meter scaling and protection
components in service. The result is that a spurious short circuit (12V rail to
ground, occurring in the ALO/Meter board) has been worked around (not concerned
about the "ALO" functions of the board -it's a mess and appears it would serve
no value at this stage). Now getting 12V when amplifier is enabled (via orange
wire from ALO/Meter J2 to contact 7 on QSK board) as originally intended. This
is forward progress and advice contributions over the last few weeks here have
been invaluable.
Next step is to begin testing QSK operation (between TS590 and LK550.)
URL of the operator's manual I'm using to explore QSK integration at end of
this post.
New question is this - does the TS590 support keying loop (so that the LK550's
KEY OUT connector would inhibit the TS590 generation of transmit RF while the
amplifier is doing it's short delay after getting KEY IN signal)? KEY IN loops
out to KEY OUT with a time delay imposed by a NE555 on the LK550 QSK board.
Should I try to interface the TS590 to the LK550 using KEY IN and KEY OUT, or
should I use open-loop control (TS590 RL signal from Remote connector to LK550
RELAY input? The QSK board appears to buffer transmit enable from the
transceiver (so the TS590's 12V 10mA limitation of it's transmit enable output
should not be a problem), however, it's not clear if/how I should use KEY OUT
to inhibit TS590?
Thanks again for the ongoing help as I/we work on resuscitating the LK550...
Dave WB0GAZ
https://manual.kenwood.com/en_contents/attachDownload/95191
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