[ARC5] Commercially made power supply for a BC946 question

[Michael Kana]

Hi all
I picked up a nice condition BC946 which had what looked to be a commercially made PSU bolted on over the dynamotor connector. 
It has a small form transformer and a 6X5 rectifier. 
There is an additional octal socket that is vacant. 
Has anyone encountered this PSU and know what went in the spare socket?  
I can provide pics for additional detail if needed. 
The RX was built by Colonial Radio Corp
Thx
Mike 
AA9IL

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