Ramsey Electronics AA7 - Manual (Page 4)

AA7 • 4
INTRODUCTION TO THE AA7
We believe that you will discover and agree with us that your new AA7 is
the best VALUE in a true receiver antenna. In its simplest form, an “active
antenna” is a small antenna going through an RF preamplifier to a receiver.
Generally, the actual antenna may be of several different styles:
•
broad-band (no tuning required)
•
fixed-tuned (i.e., pre-set for a specific frequency)
•
variable-tuning (permits peaking or “pre-selecting” a variety of band
choices)
It is easy to assume that the “ideal” active antenna would peak your
desired signal or frequency band. Several excellent active antennas are
available for this purpose in the $75 - $150 price range, but we would point
out that using this kit plus an additional $1 in mini coax to approximate your
antenna will work as well, or even better. In our humble opinion, if you really
want to spend that much money, you’re better off spending an extra five
dollars and buying a good quality receiver. (Study the Ramsey HR-series or
our SR-1 shortwave receiver, and you will see how easy that idea can really
be!)
If what you want is a great quality active antenna for a whole lot less than
others sell it for, the answer is obvious. The Ramsey AA7 active antenna.
An active antenna is a compromise between what is ideal... and what is
real. Real antennas are wire or tubing properly measured in meters, not
transistors or variable capacitors. If you find yourself in a difficult antenna
situation for casual listening or monitoring, we think that you’ll get more
satisfaction from understanding and using your AA7 than from wishing that
you spent your money on a tunable model would result in a real antenna!
CIRCUIT AND DEVICE DESCRIPTION
The AA7 features two independent, switchable RF preamplifiers. The HF
(high frequency) section is located on the upper middle section of the
schematic on page 6, while the VHF (Very High Frequency) / UHF (Ultra
High Frequency) section is located on the lower middle section.
Simple switching circuits play a major role in the practical use of the AA7.
S2:B connects the RF input and output connectors in the “power off”
position. This gives the receiver non-amplified access to the auxiliary
antenna jack, as well as the on-board rod antenna. With S2 in its “power on”
position, S1 selects between the two independent antenna amplifier
configurations (HF or VHF).