There seems to be a certain amount of misunderstanding as to how to
properly adjust audio levels in the 210. Hopefully, the following will
to clear up the procedure.
1) The level from the receiver to the RC210 is adjusted by the respective
trimpot for each port. They are marked "P1 Disc" for Port 1, "P2 Disc"
Port 2 and "P3 Disc" for Port 3. These are the pots you adjust to obtain
.75 volts peak-to-peak at the test point for that port (TP1 for Port
for Port 2 and TP3 for Port 3).
These levels should be set BEFORE setting ANY of the transmit audio
and if set correctly, the level to the DTMF decoders will be correct.
these are adjusted, LEAVE THEM ALONE! <g>.
2) Once the input levels are set, you can now set the transmit level(s).
The RC210 produces high level output, which is done to minimize hum
noise. The Tx level adjustments (the pots are marked "P1 Tx", P2 Tx"
Tx") should be smooth and not be particularly critical in adjustment.
they don't adjust smoothly or a few degrees of rotation makes a huge
difference in transmit audio level, this is a good indication that
transmitter's audio input "sensitivity" is much lower than the 210
supplies. The cure for this is easy - insert some resistance in the
Audio Output line, from the controller to the xmtr's audio input.
The value of this resistor depends on several factors (such as the input
impedance of the transmitter) but 1K is a good starting point for most
applications. The goal is to provide a smooth and generally uncritical
adjustment of that Port's Tx level pot.
Once you've gotten the above handled, you can then adjust the tone and
speech levels where you want them. BUT.. your first priority should
get repeat audio adjusted as above.
Hope this helps a little