I will do some editing of this post so wait till I mention I am done, as I am going to do some research on documentation from Riders and Beitmans seem to be in conflict on using a external cap on the generator.
Make sure to have and use isolation transformer, for the radio. The use of an isolating capacitor is not recommended, as A-C through the capacitor will introduce hum modulation and/or create the possibility of a burned-out signal generator antennuator.
First point don't hook up ground to ground.
I will digress a little bit first. I will look-up the schematic if I can, so we are both on the same page.
I found Schematic in Bietmans 1947 (Vol 7 page 50)
Following instructions :
l. Turn dial scale pointer as far counterclockwise as pos- .
sible The pointer should coincide with the first marking at
the left of the scale. If it doesn’t, remove chassis and slip
pointer on shaft until the pointer is under reference mark
when chassis is bolted in place.
2. For l-f and r-f allgnments, the (AC) Output meter ls Con-
nected across the loudspeaker voice coil terminals.
3. Keep radio volume control at maximum and attenuate
test oscillator signal output so that the output meter reading
never exceeds 1-1/4 volts.
4. The chassis must be removed from the cabinet during
I-F alignment, For R-F alignment bolt the chassis in the
cabinet securely.
5. Connect the capacitor as listed ( .05mf ), between
the output "high Side" of test oscillator and the point of
input specified.
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