This is interesting. Have you (or anyone else in the group) actually
used a preselector and/or highpass filter with a 7030 and found it to
result in improved performance? The 7030 is said to have such a robust
front end that additional filtering is the last thing I'd expect to
make a noticeable difference. In fact, I'd expect whatever tiny
improvement that resulted from the extra filter to be outweighed by
insertion loss.

However, I have an open mind about this--as well as a Kiwa highpass
filter, standing by.

Steve