Decided to separate the noise and the bridge for convenience.
Here's the new box for the noise generator, again an old if transformer can:
I could had placed the battery inside but would be a little crammed and difficult to change so a small patch was made:
For the bridge itself, I had no small (in size) variable cap to put inside so improvised with an polivaricon and the shaft of a defunct pot
Some grinding was needed for the rotating knob of the polivaricon (it was from a pound shop radio).
Some "Araldite" glue after...
And here's the the bridge. Scale is to be finished, I only placed the 50 Ohm mark and the 68p "unknown" internal cap (close to half the varicon) on the reactance side:
Inside, lot's of space left if chose latter on to put an internal noise source.
Preliminary tests made to my dipole have the same result as on the MFJ equipment.
Have a nice weekend.