Newbie + questions: C123 and Racal 6103

Joerg Albert jal2 at
Sat May 15 00:07:08 UTC 2010


I've recently got pointed to this project. Haven't dealt with any GSM software since the mid-90ies, so I thought it may be some fun
to look at the software and participate if I find enough time. I've got access to a Racal 6103 and a C123 to start with.

A couple of questions:

1) Do I need attenuators if I wire the C123 to the Racal? Guess not, but I don't want to fry the input of the Racal.

2) External antenna connector on the C123 seems to be a MS-147. I got a couple of HF cables from a WLAN card with
   this connector:,%20CG-B1%20-%203.0mm,%200-6GHz,%2090%B0%20r/a

but the inner conductor of the plug seems to be a bit short (may be my fault during assembly).
Does the MS-147 jack on the C123 switch off the internal antenna if anything is plugged in?

3) Does the PA of the C123 survive without any antenna connected (i.e. if it gets most of the HF reflected back) e.g. in continuous transmit mode?

4) A C123 without battery doesn't start the vendor firmware, display is blank, LED are on, flicker from time to time.
Is this a hardware problem or just the vendor firmware missing the battery, i.e. any problem to download osmocom software without any battery?

Thanks for any answers!

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