New product ST940B covert half loop autotune HF antenna - RF Cafe Forums

RF Cafe Forums closed its virtual doors in late 2012 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2012, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts. Here is the full original RF Cafe Forums on Archive.org

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster

Guest
 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 george@stealth.ae (Stealth Telecom Ltd.)

installed...

RMR assy...

Image

antenna tuning units...

Image

antenna remote control unit

Image

main unit

Image

stealth flyer

Image

Specifications

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 @

70-90º

Bandwidth

(Measured at VSWR 2:1) 20 kHz at 3.0 MHz Carrier

260 kHz at 15.0 MHz Carrier

Gain

(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.

NOTES:

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