I built and used two of these preamps, originally described in the August
1988 issue of QST,
p. 22 "Preamplifier for 80 and 160M Loop and Beverage Antennas". The circuit also appears in the W1FB Design Notebook . The author also described a similar preamp in W1FB's Antenna Notebook, p.110.
Both units I built from the QST article worked extremely well, though the second one had a ground loop created when the shield for one of the coax jumpers was used to provide DC ground for the board....a no-no under any circumstance and a slipup on my part during construction. Over a 3 year period, the preamplifiers proved their worth in helping to dig the really weak ones out of the noise.
I have only one criticism of this circuit, and it involves running the unit at substantially reduced gain. At full output down to about 18-20 db or so there seems to be no problem...the preamp works extremely well. However, the CA3028 begins to produce noise as its gain is reduced below this level, and the increase in noise overcomes any increase in signal one might obtain.
So,if you need only 10 db of gain in a preamp, do not build this
unit. However, if you need 20db or more gain for a loop, an EWE, a short
Beverage or some other low-noise receive antenna, then this circuit will
work very well. As with the KD9SV preamp, high quality boards are available
Far Circuits for $3.25US.