I noted the 73 material good LF material but not so good at over 10 mhz.
When going for odd ratios adding turns sometimes works better.
Or if minor loss is tolerable use a lower ratio and load down to it with
resistor. It can be more predictable as the input admittance of the
ne/sa602 does change with increasing frequency. Use the spec numbers of
1.5K (single ended/3K balanced input, and 3pF plus layour capcitance
across it). Internal capacitance inter- and intra- winding of the transformer
is a factor as well. FYI balanced input doen't not have a bypass cap to ground
from pines 1 or 2 and uses a centertap. So the typical with a 100nf to ground
on pin-2 is single ended 1.5K. Its often confused or at worst never stated.
The 4x50 inductance is rather low and would hopefully be at a frequency below
your extreme bottom frequency. My rule of thumb is 5x or higher and then
do analysis on how the source may interact with that.
Allison
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