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High Performance
Inline Rf Switched
Amateur Preamplifiers

rf switched preamplifier Features:

Low noise figure
Automatically switches off during transmit
25 watt through power capability
No transceiver modification necessary
High immunity to overload
Completely shielded
Small size
Rugged low profile custom enclosure

Series SPXXXVD, SPXXXVDA and SPXXXVDG preamplifiers have been designed for the most demanding commercial and military applications. Each model has been optimized for the lowest noise figure consistent with excellent strong signal handling capability. These preamplifiers are suitable for use in any receiver or converter/receiver system. Each preamplifier is housed in a rugged low profile custom aluminum enclosure finished with military grade black urethane enamel. Female BNC coaxial fittings are provided for the input and output connections. Other connectors or connector combinations are available. Complete rf shielding is maintained with a feedthrough capacitor for the dc power connection. Mounting holes, suitable for #4 hardware, are located at each corner of the bottom plate.

Several models of preamplifiers are available for most frequency ranges. Selection of the most suitable model for a particular application will depend primarily on the noise figure and overload characteristics required. Preamplifier models using dual-gate MOSFET and bipolar transistor devices (part numbers with suffix VD or VDA) are suitable for most scatter, tropo, satellite, ATV, repeater and radio telescope applications. Gallium-arsenide FET (GaAsFET) preamplifiers (part numbers with the suffix VDG) provide the lowest noise figures and highest immunity to overload of any preamplifier types. These preamplifiers would be well suited for very low signal level work, either terrestrial or earth-moon-earth (EME) communications, or in areas where strong signal levels are normally a problem.

Extensive testing of these preamplifiers on existing communications systems indicate that a signal-to-noise improvement of 6 - 14 dB can be expected. For example, a 10 dB signal-to-noise improvement in a mobile receiver performance would give a 100-watt base station or repeater the same range as a 1000 watt unit! Each and every preamplifier is precision aligned on our noise figure measuring equipment and should provide long trouble free operation.

Inline preamplifiers use rf sensing to detect the presence of transmitter power and immediately switch the preamplifier out of line. The rf relays used in the preamplifier will handle up to 25 watts of rf power. In systems where power amplifiers are used, the inline preamplifiers may be installed between the transceiver or transverter and power amplifier. Connected in this manner, the preamplifier need only handle the transceiver power (25 watts or less).

All preamplifiers are designed to be powered by a 10 - 16 volt dc source with a current consumption of 100 mA. Low power consumption along with the small size make these preamplifiers ideal for installation within existing equipment or systems, or for remote mounting at the antenna. Mounting the preamplifier at the antenna will provide the best system noise figure.

Specifications

Model



SP28VD
SP50VD
SP50VDG
SP136VD
SP136VDA
SP136VDG
SP144VD
SP144VDA
SP144VDG
SP220VD
SP220VDA
SP220VDG
SP432VDG

Freq.
Range
(MHz)

28-30
50-54
50-54
136-138
136-138
136-138
144-148
144-148
144-148
220-225
220-225
220-225
420-450

N.F.
(dB)


1.2
1.4
0.55
1.6
1.1
0.55
1.6
1.1
0.55
1.9
1.3
0.55
0.55

Gain
(dB)


15
15
24
15
15
24
15
15
24
15
15
24
18

1 dB
Comp.
(dBm)

0
0
+12
0
0
+12
0
0
+12
0
0
+12
+12

1 dB
Bandwidth
(MHz)

2.5
5.0
4.0
8.0
8.0
7.0
8.0
8.0
7.0
10
10
12
30

Device
Type


DGFET
DGFET
GaAsFET
DGFET
DGFET
GaAsFET
DGFET
DGFET
GaAsFET
DGFET
DGFET
GaAsFET
GaAsFET

Price



89.95
89.95
129.95
89.95
99.95
129.95
89.95
99.95
129.95
89.95
99.95
129.95
129.95

Supply voltage: 10 - 16 Vdc
Supply current: tx - 10 mA, rx - 100 mA
Weight: 4.0 oz.
Through mode VSWR: 1.25 max
Through mode attenuation: 0.5 dB max
Minimum power to rf switch: 0.5 watt
Dimensions: outline drawing

Prices shown for standard BNC connectors
Add $10 for N, SMA - other types available
For custom frequency ranges see
Special Frequency Ranges or contact factory

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