[1000mp] MkV Amp interfacing questions

[lhlousek]

Hi Earl,

I started this thread with respect to hooking up an Ameritron AL-800H amp with the internal QSK-5 PIN diode T/R
switching option.  Rather than using the amp keying relay in the MkV, pin 2 of the Band Data jack is used to key the
amp.  The QSK-5 requires that the TX "relay" line go low at least 1msec prior to RF being present at it's input.  With
the MkV, the required 1 msec delay can be set in menu item 7-4.  This setting does not simply clip the first dot or dash
but delays the entire CW string.

The QSK-5 also has a TX open collector inhibit line that pulls low when the QSK switch is ready for RF after it gets
keyed by the "relay" line.  This can be used as a safety to prevent the exciter from transmitting before the QSK-5 has
switched to TX mode.  The inhibit line is connected to the MkV's TX inhibit input which is pin 8 of the Band Data jack.
However, this will have no effect unless pin 8 is first pulled high inhibiting TX.

To pull the inhibit line high I put a ~2K pull-up resistor between pins 1 and 8 of the band data jack but this had the
unintended effect of disabling MkV TX when the amp was powered down.  I have since removed that resistor and added the
pull-up resistor on the QSK-5 board so when the amp is off, there is no inhibiting voltage on pin 8.  Now the MkV well
transmit with the amp off, with the amp on and in standby, and is inhibited from transmitting when the amp is in line
unless the QSK-5 switch is ready.

Anyway, the end result is that QSK wise, you can't tell the amp is in line.

BTW, with this amp you should most definitely use the ALC line.  It greatly simplifies tuning by preventing the amp from
tripping off line due to high grid current.  Of course by doing this, it might also prolong the life of the tubes. It
can be set high enough so as not to clip or cause distortion (which according to Ameritron, it doesn't do anyway due to
it's progressive nature) when the amp is properly tuned,.

Lou W7dzn