At 02:16 PM 08/10/09, you wrote:
Hi guys .thanks for the replys .The fault was I had too much length
between the radio and the ctcss decoder card .I have altered most of
my repeaters to allow the maxons to decode the signal by itself and
then it controls the transmitter by the maxon approved design with a
bs170 fet .I have now developed a interface circuit that has no
relays for switching audio .and the new design uses a 4066 audio IC
to switch audio paths .It has reduced transmitting delays very
well .Now the repeaters seem to work almost as soon as a signal
comes in .One repeater decodes even if the signal is just below the
mute .I need to find out how that one works.All in all very happy I
have found the problem .Now I have repeaters with no ctcss breakup.
Thank You,
Ian Wells,
Kerinvale Comaudio,
361 Camboon Road.Biloela.4715
Phone 0749922574 or 0409159932
<http://www.kerinvalecomaudio.com.au/>www.kerinvalecomaudio.com.au
If you have not cast your design into concrete yet you might
want to make one parts change.
Use the 4053 (3 SPDT switches in one package) instead of the
4066 (4 SPST switches).
Use the SPDT switches to feed either audio or audio ground to
the next circuit downstream. With SPST you can only open and
close the audio path leaving the downstream input floating when
the switch is open. This can lead to hum, or at a site with high
RF levels, other grunge.
Rarely do common interface circuits need 4 switches, and the
cost of the chip is pretty much the same.
Mike WA6ILQ
