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New Product ST940B Covert Half Loop Autotune HF Antenna - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Original posts:

Amateur Radio | Antennas | Circuits & Components | Systems | Test & Measurement

 Post subject: New product ST940B covert half loop autotune HF antenna
Posted: Tue Feb 07, 2006 6:30 am 
Tentative batch of 30nos of ST940B antenna system is released. System is developed by request of UN. Please address all comments to (Stealth Telecom Ltd.)


RMR assy...

antenna tuning units...

antenna remote control unit

main unit

stealth flyer


General Specifications ST-940B
Frequency Range 2.7 ? 15.0 MHz, ±2%
Power Rating 125 W PEP
Input Impedance 50 ohms
VSWR Not greater than 1.3:1
Pattern Radiation Omni directional, HRP offsets are less than 1 dB at two opposite minimas,
Vertical Elevation ? NVIS lobe @
(Measured at VSWR 2:1) 20 kHz at 3.0 MHz Carrier
260 kHz at 15.0 MHz Carrier
(compared to ideal 1/4? GP*) -0.32dB @ 15 MHz; -1.27dB @ 7 MHz;
-2.17dB @ 3.5 MHz;
Power Supply Voltage 12-14VDC/ 4 A (peak current)
Tuning Method Continuously Variable Tuning
Tuning Time 3 seconds average, 8 seconds max.
Tuning Accuracy ± 1.8º step or :
Approx. ±200 Hz at 3.0 MHz
Approx. ±15 kHz at 15 MHz
Tune Signal 4-30 W PEP CW followed by logic
consequence via 4 I/O programmable interface
Tuned Point Instability
Wind/Vibration Not detected at speeds up to 150 km/h
asphalt and up to 90 km/h off-road

Tuned Point Thermal Instability
(within 3 min under 100 W PEP CW) Less than 500Hz negative
drift @ frequencies below 4 MHz
Less than 10Hz negative drift @
frequencies above 4 MHz
Feeding method Shunt fed, ?-match in series with
preset reactance
System Serial Bus RS-485, differential
Programming Port RS-232
Dimensions H x W x L,
(without mounting brackets) Folded Up: 740** x 1254 x 1852 mm
Folded Down: 175 x 1254 x 1852 mm
Weight (without mounting brackets) 36 kg
Sealing Withstands rain testing per MIL STD 810 C/D/E
Shock/Vibration Protection provided via Impact
resistant vibroframe
Dust and Humidity Protection provided via environmental
resistant housing to MIL STD 810
C/D/E and connections to MIL C26482.
* If compared with mobile loaded whips approx. 0.6 dB to be added at all three frequencies.
Data is specified for +25Cº unless otherwise stated. All specifications listed are typical.
Specifications are subject to change without notice and are issued for guidance purpose only.

Posted  11/12/2012

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