开云体育

There are jumper changes when you install/uninstall a CTCSS board. I
know one is on the front/left side of the system board (with the handle
facing you). That is the PTT control jumper that selects normal PTT vs
Delayed PTT. With the jumper in the 'CTCSS' position, the unit will not
transmit (using the PTT line) without the CTCSS board actually being in
the unit. If you jump 10V to the oscillator control, the unit will TX
anyway and this jumper doesn't apply since that point is after the
jumper. I don't recall where the others are offhand. I don't have the
manuals at home. Check the voltages at the points labeled RX MUTE -
that's on the connector on the system board that is on the extreme
right. SQ Disable should only disable CTCSS and should not itself open
the squelch but RX MUTE will open the squelch. When squelched, RX MUTE
is a logic low (0V). One word of caution if you don't already know - the
label on that connector (J903?) is *usually* offset a little from the
pins, so make sure you are looking at the correct pin.

Well, back on topic, the unit should not open squelch just due to the
removal of the CTCSS board. Unplug the board - the RX becomes CSQ with
no jumper changes necessary. The RX MUTE (NOT CAS) will even work as a
CSQ unit. Of course, CAS always follows the receiver regardless of CTCSS
presence. Does the unit receive on the selected frequency?

OH! Check your 10V supply! That could open the squelch. It has to be
10V +/- a few hundredths.

I want to correct something I said earlier. I believe an *internal*
squelch WAS an OEM option on a Mastr-II. It was rare, but I think I do
remember seeing a unit that had one. The only control on the C/HD was
volume and on/off.

Ed Bathgate, RMA Repair Dept x8785 wrote: