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Ultra low noise Active Loop Antenna Model ALA1530LN

A new version of the world famous Wellbrook Active Loop ALA1530

As of April 2021 the amplifier gain has been increased to 28dB

Oct 09, 2009 ULTRA LOW NOISE SINGLE P-CHANNEL JFET PRELIMINARY Linear Integrated Systems. 4042 Clipper Court. Fremont, CA 94538. Tel: 510 490-9160. Fax: 510 353-0261 Page: 1 OF 2 File: LSJ7409OCT2009PRELIMINARY.DOC Revision Date: 10/9/2009. The FET-input architecture achieves a low 2.9-nV/√Hz voltage noise density and 6-fA/√Hz current noise density, allowing for very low noise performance in a wide variety of circuits.

Amplifier with low-noise low-power operation is proposed. It utilizes JFET as the input device to provide much higher input impedance than BJT and much lower noise than MOSFET. Besides, the closed-loop gain is set by current feedback technique 9 and an additional feedback path provided by sensing terminals, instead of capacitive feedback 3, for. Linear Integrated Systems (LIS) announces the immediate availability of its LSJ689, a 1.8 nV/Hz @ 1 kHz, low-capacitance, monolithic dual P-Channel JFET. The LSJ689 is a P-Channel complement to. Ultra low noise amplifiers.

This Balanced low impedance Magnetic loop has enhanced performance compared to shielded and Moebius loop types.
The new JFET design affords a considerable reduction of noise compared to low cost loops using MMIC (Monolithic Microwave Integrated Circuit). MMICs are designed for Microwave use and therefore are unsuitable for LF to HF loops. Furthermore, MMICs use integrated resistor feedback, which limits the noise figure to a minimum 3dB at HF. At Medium Frequencies loops using MMIC amplifiers can have a Noise Figure as high as 8dB plus high IMD (Intermodulation Distortion).
Compared to the W6LVP loop, the ALA1530LN affords a much lower noise floor with an average of 6-8dB higher gain with much lower IMD.
The ALA1530LN has a noise figure of approximately 0.2dB which give a noise floor that is 13dB lower compared to a similar gain loop with a noise figure of 3dB.
This antenna and its big brother, the ALA1530LNPro Imperium are the only 1m dia. Active loops in production to use an ultra low noise JFET design. The loop has recently had a significant design change to improve LW/MW and SW reception. The ALA1530LN has been engineered to increase the LW and MW signal to noise ratio s/n by up to 10dB and provide an increased s/n on the HF bands. The LW and MW 3rd order IMD is now approx. 20dB lower. This being a combination of reducing the gain a little and the lower IMD of the JFETs
The new ALA1530LN is the second generation of this antenna and uses 8 very high gain JFETs in parallel push-pull with a Bipolar transistor cascode stage for extended bandwidth. A very low amplifier noise floor is achieved by dynamically decreasing the JFET Source resistance to a fraction of an Ohm. This is achieved using a proven technique developed in the 1980s by coupling the FET Gate to the Source with a phase inverting transformer.
The loop works by designing amplifier so that the very low noise of the loops real resistance is mismatched to the input impedance of the low noise amplifier. Hence, reducing the amplifier noise floor by up to 13dB compared to more conventional low noise amplifiers. Also JFETs are less noisy at low frequencies compared Bipolar transistors. The amplifier also has a rising input impedance versus frequency to match the loop's reactance; this together with Ultra low noise JFET design is a technological breakthrough.
The mechanical design is now improved to afford increased reliability and to facilitate ease of servicing:
The amplifier is now house in a separate module, thus isolating the electronics from the mechanical stress caused by wind loading on the loop. The amplifier to loop wire terminations use tin plated silicone insulated wire and crimp terminals rated down to –40 Celsius. The module sits on of the loop box and is secured by stainless steel screws. The base of the loop is now reinforced with an acetal rod to minimised damage due to weather extremities.
The amplifier module can be easily replaced in the unlikely event of a failure, without the customer having purchase a new loop antenna with the associated high shipping costs.
A resettable fuse and a power on LED are now fitted to the Antenna Interface. Additionally a power limiter is fitted to reduce overload of receivers co-located with transmitters.
This unique broadband magnetic antenna is only 1m diameter and rotatable to provide deep nulls to reject noise and interference. This new broadband untuned Loop antenna is the only active antenna designed specifically to reject locally radiated and mains borne noise from TVs, computers, mains wiring etc.
The Loop antenna responds primarily to the Magnetic Field and rejects locally radiated Electric-Field noise providing far lower noise reception than active whip/dipole antennas. Compared to active whip/dipole antennas, the Loop will reduce locally radiated noise by up to 30dB and mains borne noise by up to 60dB. The ALA 1530LN has 30dB nulls to further reduce interference.

It is ideal for small gardens, indoors and directional reception using an antenna rotator.
The ALA1530LN offers significant advantages over the traditional tuned Loop, because the Loop can be used away from local interference. Whereas, a tuned Loop has to be positioned next to the receiver where there are high levels of local noise.
This antenna is probably the most advanced broadband active Loop antenna available to the Radio Enthusiast, offering professional performance at an affordable price. The Loop antenna is supplied with an Antenna Interface and a 12-volt regulated Power Supply.

Product Details

• Brand: Wellbrook
• Product Code: ALA1530LN
• In Stock

New Flexible version

• £282.00

• Ex Tax: £235.00

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Tags: Loop, Antenna, ALA1530LN

Linear Systems announces the re-release of their most popular part, the LSK389 Series, Ultra-Low Noise, Monolithic Dual, N-Channel JFET, now 100% tested to meet or exceed noise specifications.

Low-Noise JFETs Ð Superior Performance To Bipolars

The LSK389 is the lowest noise Junction Field Effect Transistor (JFET) in its class and has been used in ultra-high-end applications for over a decade. The LSK389 enables developers to create the lowest noise signal chains possible for sensors, professional audio equipment, and other applications.

Linear Systems is releasing the LSK389 after creating the capability for individual screening of small-signal discrete components to levels below a billionth of a volt (nV/√Hz) of noise in quantities up to tens of thousands of parts. This testing capability – the only one in existence worldwide – ensures all LSK389s leaving the factory produce no burst (RTN or popcorn) noise and meet or exceed 1/f and broadband noise specifications.

The LSK389, Ultra-Low Noise, Monolithic Dual, N-Channel JFET provides designers with a better-performing solution for obtaining tighter IDSS matching and better thermal tracking than using individual JFETs or non-monolithic dual JFETs. The part is an ideal combination of high transconductance, ultra-low noise, and relatively low input capacitance.

The LSK389 is the lead part of Linear Systems’ family of low-noise JFETs. The LSK170 is the N-channel single version of the LSK389, and the LSJ74 is the P-channel counterpart to the LSK170. The N-channel dual LSK489 has slightly higher noise but lower input capacitance than the LSK389, and the LSJ689 is its P-channel dual counterpart. In addition to the LSK-series, all Linear Systems’ JFET standard products have substantially lower noise than those made by other manufacturers and are marketed under the Improved Standard Products trademark.

Linear Systems is a full-service, privately-held, 32-year-old designer and manufacturer of small-signal discrete semiconductors. The Fremont, CA-based company was founded by John H. Hall, co-founder of Intersil and founder of Micro Power Systems.

Linear Systems specializes in the development and manufacture of precision, ultra-low noise small-signal discrete components. Its parts are used in highly demanding sensor systems ranging from the Large-Scale Synoptic Telescope to piezoelectric devices to sonobuoys. These parts also provide the front-end amplification for high-end test and measurement, medical and audio equipment.

1,000+ pieces of the LSK389A SOIC 8L package is $4.67 (USD) each. 1,000+ pieces of the LSK389A TO-71 6L package is $6.70 (USD) each. Prices vary based on grade (A, B, C and D) and quantity.

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Ultra Low Noise Jfet