[Alinco] Alinco DX-70T problem

[Corky Kirk]

3-13-05
This is in reference to my last posting and problems
identifying the KEYING RELAY circuitry.

Checking out the DX-70T manual, it only refered to
"cut a jumper" to make the RELAY JACK work.  The
problem was that I couldn't find the "jumper" nor the
connector on the schematic!

So I opened up the bottom of the DX-70T, located the
"jumper" and found the identification R534 next to it
and right where the picture showed it (on page 7.2 of
the manual). Incidently, in the picture it looks like
a resistor, but is really a jumper with a white
ferrite core on it. 

Then got out the magnifying glass and searched the
schematic for the 500 series resistors and found them
in the FILTER UNIT. Shown was R534 and a value of "Ø"
ohms!  Checked out the circuit and found this jumper
served to hold Q609 in the PA UNIT low (base to
ground) and by cutting the jumper, it let control of
Q609 be given to Q504 that operates off the control
voltage and actuates the DX-70T "send-receive" relay.
Otherwise the relay never closes. 

With the jumper cut and when PTT is accuated, it
changes the condition of Q609 and now closes a relay
(RL603) and voilá, the EXTERNAL RELAY JACK center
conductor now goes to ground and closes the transmit
relay in the SB-200.

So I cut the jumper, plugged in the SB-200 control
line and pushed the PTT button on the mike. The SB-200
relay operated as advertized.

Hope this info helps the next guy to understand the
manual and what "cutting the jumper" does.

Corky Kirk  W6ORS
Hilo HI




__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com