Updated 24-09-2009 (repeater up again, upgrade will be soon! )
Some mod's to come on this pages:
VHF Stornophone CQF 9000 Repeater for JO22RD
Ascom SE 550 Multi Repeater Station
The Ascom SE 550 project: “Up 431.350 (RX) & Down 438.950 (TX)”
My Ascom SE 550 modifications to a repeater
I allways wanted to build a repeater-crossband system.
The system should do the following, using 3 Ascom SE 550's (1x VHF & 2x UHF):
70cm repeater with 7.6Mhz shift with a connection to a 2m band frequency From the
2m band freq. you can connect to the 70cm repeater output freq
And all the traffic from the repeater will be connected to the 2m band freq
The 5 volt RX detection question
The problem was how to detect a RX signal from one SE 550 and then let the other
SE 550's TX.
There was no standard point for detection of RX and no documents showed a RX detection,
undocumented! I know that a lot of radio's have a point that signals RX and can be
used for switching other sets to TX. This took me some time to find out where i could
find a point in the SE 550's when RX is active,
I now have a point of 5 volt when RX is detected and 0 volt when squelched.
Below some pictures where to find this hidden secret of a 5 volt stable RX detection
The point is 5 volt and with a optocoupler the other sets are switched to TX.
A 1K ohm connected to the optocoupler on this 5 volt and one ground wire.
The output of the optocoupler is switching ground to set the other radio's on TX.
I have some other work to do as a little hangtime before disconnecting, i am thinking
of a NE555 for this.
The system is currently up with only a 70cm repeater function, i must buy some more
The system covers a 10Km area from my location JO22RD.