I'm in the check-out phase of building the AT Sprint 3A and not getting
exactly what the manual calls out for the reading before L3 is installed.
The procedure on page 20 calls for a voltmeter to be connected between
ground and the
Drain of Q4 then to send a string of Dah's while watching the voltmeter.
Then the procedure says
the voltmeter should go near the DC supply voltage then slowly decay to
zero when I stop sending the Dah's.
I'm using a BK 40 MHz scope to make the readings (I've also used a portable
DVM and analog multimeter with similar results) and find that the unit will
not start sending until I lift
the scope probe off the Drain of Q4. Once I lift the probe the Dah's start
and I can put the probe back on the Drain of Q4 and see the scope trace is
supply voltage. When I stop sending the Dah's the Drain voltage decays to
zero per procedure. I'm using a new 9 volt battery for the power supply.
Is this a good reading? Should the Dah's start with the scope/meter
connected? Has anybody else had this situation?
I've checked all the components on the board for good connections and can't
find any problems.
Thanks for your comment on this situation.