I am trying to scale an existing front end receiver (butterworth
bandpass) filter to a different frequency range. Unfortunately, it has
a transformer in the original design, so I'm stuck. I also don't know
how to handle the load presented by the active front end component
other than it's probably not significantly reactive.

The existing filter is for a 7 Mhz receiver, I'd like to have a
similar filter design for 50 to 200 Khz.
===========================
If you are happy with the HF receiver as is, would it not be easier and
more effective to build an LF (50 - 200 kHz) to HF converter. This should
be an easy project and you can select a quiet "HF band" for the conversion.

I have seen designs with a SBL-1 mixer but also a number with the NE612
osc/mixer. Perhaps others frequenting this NG have built such a
converter.

Frank GMØCSZ / KN6WH