Topband: W7IUV Preamp from Low Band DXing

[Ford Peterson]

I have a need for a preamp with what seems to me to be a simple twist.
Perhaps somebody can suggest a modification that will work for my needs.

My station has 4 Rx antennas.  Each has a different signal output.  Each has
unique pattern characteristics that I can use to my benefit under various
circumstances.  Controlling the signal output of each antenna to make them
comparable is important to maximizing S/N while minimizing the number of
knobs and switches.  I'm thinking that I need to install a preamp on each
antenna to bring the signal levels up to a point where the noise floor is S0
on each--all while leaving the ATT setting on the MKV alone.  One antenna
may need 10dB.  Another 20dB.  A fixed output on the preamp is useful for
gain, but must then be followed with a variable attenuation to make the gain
precise and the antennas comparable.  Without the antenna "presets" I need
to also mess with the ATT controls on the radio.  ARRRGGGGHHHH!

I envision a box with 4 preamps.  The box must either have variable gain, or
followed by variable attenuation.  I would like the box to have 4 inputs,
and one output.  Using the MKV In/Out connection is useful for inserting a
fixed gain.  But I need that gain to switch simultaneously with each antenna
selected.

How would I modify the W7IUV design to accomplish make it variable gain?
I'm thinking the box needs 4 preamps so that when any antenna is selected
with one switch, the gain is precisely calibrated to bring the noise floor
on that antenna to S0.

Any thoughtful responses would be appreciated.

73

Ford-N0FP
ford at cmgate.com