Welcome on PB2GT / SA6BIG

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 point.

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 parts Hi.

The system covers a 10Km area from my location JO22RD.



My MOD's Page


Repeater specifications & options:

The system broadcasts it's ID every 4 minutes and DTMF echolink functions are active .not active!

But first the frequencies of the system and echolink: 70cm Repeater: uplink 431.350 Mhz / downlink 438.950 Mhz ( 10 watt output ) Active, 2m simplex: 144.6375 Mhz ( 10 watt output ) not active!


Echolink: (not active momentairly)

Connect to PB2GT-R (Repeater) direct connection to 144.6375 (RX & TX) & 438.950 (TX) & 431.350 (RX) not active!

For any questions to the system just contact me.

NOTE!! This system is only active when i am at home!


Latest news,

24-09-2009 Repeater is up again, soon I will upgrade the system TX to 30w output.

Next upgrade will be a complete new CQF 9000 UHF repeater expected somewhere in 2010


Earlier news

Adjusted the repeater audio, this was a fault in the audio circuit.

Next step:

Adding a 2m gateway to the repeater ( uplink only as start )

I have pictures of the 5 volt detection, if you want to know this point, just contact me

The 5 volt RX detection point on the processorboard behind the head.


For any questions about the repeater or RX detection, just contact me


Best 73!