I have received my new toroids (BN-73-202) and have been having a look at the difference between them and my FT37-43 ones. In this reply I have attached three images.
The first is the NE602 with an FT37-43 on the input and output - with -30dB in at 10MHz the output is -15.79dB
The second image has a BN-73-202 on the input and an FT37-43 on the output - here the output is -23.69dB
The third image has a BN-73-202 on both input and output - here the output is -33.98dB
From these tests I can see that lots of the harmonics disappear when using two BN-73-202 toroids but the gain drops quite a bit.
I did try adding and removing turns on the BN-73-202 but the best ratio seems to be 0.5 to 8 (1 full turn on the primary reduces the gain and matching).
I will post the NanoVNA results in the next reply.
