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FLAG, KAZ Antenna Amplifier FLG100LN

Brand: Wellbrook
Product Code: FLG100LN-1
Price: £150.00
   - OR -   
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New Low Noise JFET Design

This new product from Wellbrook is designed to provide a high impedance match to terminated Flag antennas and provide high gain and low noise. This product replaces the FLG100.

The FLG100LN uses a low capacitance 800 Ohm antenna matching transformer to galvanically isolate the antenna from the feeder. This approach offer much better isolation than a FET buffer and transmission line balun. Poor isolation can degrade the antenna pattern.

The amplifier is based on the new ALA100LN and uses4 high gain low noise JFETs in parallel push-pull, cascode with optimum noise-less transformer feed-back resulting in a much lower amplifier noise floor. This lower amplifier noise floor is achieved by dynamically decreasing the JFET Source resistance from approx. 10 Ohms to  less than 1 Ohm.

The Head Amplifier affords other benefits; being balanced it provides common mode rejection to noise or signal on the feeder screen. Also the high gain (23dB) raises the wanted signal well above common mode feeder pickup at the receiver. The Head amplifier is ideally suitable for low output Double loop antennas, e.g. George Wallner’s Double Half Delta loop (DHDL) and Neil Kazaros’s Double KAZ Delta antenna (DKAZ). These antennas are effectively two loops on the same axis running in anti-phase. This produces an antenna pattern that is very similar to a “cross-fire” phased array of two Flags.

Product Details

The following examples show various Delta Flag configurations and details of DHDL ( Double Half Delta Loop). This is reproduced here by kind permission from George Wallner.

Single Delta Flag.pdf

Double KAZ.pdf

Double Half Delta Loop.pdf

UK and European version with psu

Pictures of FLG100-LNs in use at Yachats, Oregon, courtesy of Guy Atkins.

DKAZ antennas going up at the Deja-Vu vacation house in Yachats.

It was a superb time to visit with other DXers from around the world and to DX from a beautiful coastal location.

By the way, the broadbanded (FLG100) Ferrite Sleeve Loop antenna was almost a dud at the cliff side location (about 1.5 miles from the Deja-Vu house at a 240 ft. altitude); Gary DeBock's DXing at the coast with an identical size and construction *capacitor tuned* FSL antenna performed excellently though. Signals were just far too weak with the broadband FSL. I'm at work on a way to switch connection methods so that the entire band can be observed for the presence of 9 kHz signals in broadband mode, and then use the 'single frequency' capacitor tuned mode to actually DX and record a DU or TP station.

All in all, though, the Wellbrook products served us very well on this DXpedition featuring EIGHT Perseus SDR receivers and 100% Wellbrook-driven antennas.


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