LF: Racal ATU Board Details

[Andy Talbot <andy.g4jnt@gmail.com>]

I picked up a rather nice PCB at the Andover Rally; the RF and relay drive unit for a Racal Auto ATU.  

It consists  of 25 reed-relays switching inductors and capacitors in a binary tree.   All relays have individualy drive electronics, and on the input to the PCB are seven  74HC595 8 bit shift register / latches.    Which gives 56 bits of drive,  twice the storage capacity of what the 25 relays look as if they want !

 

Does anyone have any information or ideally a  circuit diagram pse.?  

The PCB is marked IATU PSB ASSY    49362-124-00         and    CCK4800  on the top side.

On the underside is marked 39362-724-00

 

PCB dimensions 190 x 130mm.    There is a 10 way header for power and data, so the switching data for the relays must be shifted in serially.  

 

Its a nice little module, and just asking to be connected to a PIC and turned into a manually set-up ATU with digital memory.   And would go wonderfully well with my multiband WSPR beacon.

 

If I can't find the serial drive requirements looks like it may be a case of tracing out the circuit which is going to be difficult as it s a multi layer board  - or ripping teh drivers out and using my own drive electronics.  At least serial input high voltage driver chips are readily availalble

 

And I'd really like to know why there is twice as much digital storage as it appears to need.     As a ping-pong buffer for frequency hopping perhaps ???

 

Andy

www.g4jnt.com