SSB-Electronic SUPER AMP GaAsFET Series Manual

SP-6/ SP-2000/ SP-220/ SP-7000
SUPER AMP GaAsFET SERIES
50,144,220 & 432/435 MHz.
Mast-Mounted Preamplifiers
Thank you for purchasing this preamplifier which is manufactured by SSB ELECTRONIC GmbH. 'Ve
believe that it is without a doubt the best available anywhere aDd would ask that you please spend a few
moments
10
read through these notes in order
to
ensure that you obtain the very best possible results
from tbis product.
The full potential of this preamplifier can only be realized when a minimum of feed line exists between
the preamplifier input and the antenna feed point. Maximum lengths are: 24 flo on SO/144MHz
and IS ft. on 432MHz assuming that a quality coax. such as AIRCOM PLUS is used. This length can
usually be achieved by mounting the preamplifier on the support mast close to the antenna mounting
point.
The amplification factor of this preamplifier can be adjusted so that a good system gain distribution can
be maintained. This is important in order to insure that the receiver front-end as well as tbe mixer are
not overloaded. The following table may be used as a guide for setting the preamplifier gain to overcome
the feedline losses encountered from your rig to the preamp.
' -
CABLE LOSSES
Under 2 dB
2 - 3 dB
Over 3 dB
GAIN SETTING
M1N
MID
M~,\(
The following table may be used as a guide to the losses for various cable types:
Frequencv
144 MHz.
432 MHz
RG58V
0.2 dB/M
0.4 dB/M
RG213
0.08 dB/m
0.15 dB/m
AIRCOM PLUS
0.05 dB/M
0.08 dB/M
A good rule oftbumb is to aim for 12 -14 dB. of gain above feed line losses.
Access to the gain adjusting potentiometer is obtained by removing the four self tapping screws from the
underside of the unit. This enables the plastic weather shield to be removed exposing the tin plated
shielded box in which a small hole will be found. Adjustment may now be made with a small screw·
driver. CAUTION: Great care should be taken when making this adjustment noting:
a) The potentiometer only rotates through 270 deg.
b) Do not exert any pressure on the adjuster
c) Ensure the screwdriver goes to the pot, and does not slip sideways causing possible damage to
any surrounding components. An insulated trimming tool would be best suited for this job!
If the tin plate box lid is removed to make this adjustment then please DO NOT TOUCH ANY
OTHER CONTROLS as these have all been carefully set at the factory for the best noise figure.
124 Cherrywood Drive., Mountaintop, Pa. 18707
(570)-868-5643