Measuring on a commercial AMfilter from ITT, type 931 AM with my DG8SAQ VNWA
From start the filter specifics
was unknown, so I made an experimental measuring with a 47 OHM resistor in
series
with a 1 K Trim Pot and made a sweep.
I found that the best and flat topoffilter was close to, but a little less
than 940 Ohm.
Then I figured the transformation between VNWA (50) and the filter (900 Ohm):
SQR of 900/50 = ~ 4,25.
I made a Toroidtransformer, 4filar ( 4 wires wrapped closely with a
drillingmashine), type:
4C65 ferrite,
9 windings total, then connected as shown.
One side to the other.  Then I connected the filter in
this way: 2 pc. trimmer at 25 pF is added. 
Setting the frequency to 10,7
MHz, plus/minus 250 KHz and CALIBRATING the VNWA,
I connected the WNVA:
You will possibly need to make a screen between filter input and output to avoid overhearing. I did by hand.
And here is the result:
REMARKS:
In the 1970'ties I used that filter in a homemade 2 meter SSBrig and it was working perfectly.

A closeup picture:
The data says:
That is it!!!
OZ6YM, dec. 2011.