I believe that they did have a high impedance input, but it has been years
since I had one. Over time, I have owned the 51J, the 51J-2, 51J-3, 51J-4,
R-388, 51S-1, and the 651S-1. They were all great receivers. I did mod a few
of my 51Js converting the cathode follower for the I.F. output to a product
detector for SSB. Best sounding SSB audio I ever had, probably due to the
wider I.F. bandwidth. Another modification for gain-hungry people like
myself was to move the output connection from the tap of one of the I.F.
transformers to the end connection, the way it was configured in the 51J-4.
Oodles of gain after that mod!

Pete

"Paul_Morphy" wrote in message
news

"Pete KE9OA" wrote in message
news
Another good receiver for MW DXing was the R388/51J series. Also, a true
test of a receiver is how well it works in the daytime. With a loop
antenna,
it should be possible to hear MW stations on the low end of the band up
to
300 miles.

That receiver was designed for use with a whip antenna, wasn't it? That
would explain the sensitivity. I recall there being a mod to improve
front-end selectivity or to prevent mixer overload, when used with better
antennas. It was in CQ, back in the Middles Ages. IMO, the 51Js were about
the prettiest receivers of the era, right up there with the earlier SX-28.
I
never had the pleasure of owning one.

73,

"PM"