I'm fully aware of what "tone burst" is and how it works, as well as
CTCSS/PL.. It was the sentence in the original post that threw me off. MNS.

"Martin" wrote in message
...

"MR NO SPAM" wrote in message
...
I don't have a manual for it but a lot of radios have a pot labeled tone
volume. Take a look. I'm confused though, your statement must have a
typo..
IF the repeater doesn't have CTCSS / PL access on it, why worry about
the
tone? There should be a switch to disable it. MNS.



Here in the UK not all repeaters are yet fitted with CTCSS for access.
and the old system was to transmit a 1750Hz tone burst approx 200ms
long then a carrier with / without audio to make the repeater switch on
the Tx and latch. The Time out timer then starts to count down.
On some repeaters once the input signal had dropped and he squelch
closed on the RX the next received carried caused the repeater to remain
latched and the T/O timer was reset if there was no other carrier for 5
seconds
or so the logic sent the callsign and the repeater closed down un till the
next time
a 1750Hz tone was received.

So to access these older yet to be upgraded boxes I need to get the 1750Hz
tone sorted out.

Any one got a circuit for the TMG707 either version ?