And Other SWR Meters

The device shown schematically in Pig. 1A is called a reflectoraeter or monimatch. The ARRL Radio Amateur's Handbook states that this device cannot be analyzed in terms of lumped parameters, however, its inventor based the design on this, stressing that the dimensions should be small compared with the operating wavelength. 1,2 The equivalent circuit of the reflectometer, in terms of lumped parameters, is shown in Pig. IB. The physically short coupling line is a capacitance to the main line, C....

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Page 9, QEX, December 1984, published by The American Radio Relay League, Inc. I recently reviewed a set of linear power amplifiers in the 50-MHz range using a number of VHF power FETs. Output powers of 100, 500, 1000 and 5000 watts were demonstrated. Unfortunately, the cost of the devices and the outrageous size of the 60-V, 50-A power supply indicates that 1500-watt output solid-state 6-m amplifiers will not be in use by amateurs for quite some time. On Attaining High Frequency Stability In...

Meter Preamplifier Using the Tl S Dual Gate GaAsFET

This article describes a 2-raeter preamplifier using the new Texas Instruments S3030 dual-gate GaAsFET device announced in this issue of OEX. The circuit presented here is adapted from a design I have used successfully with other dual-gate GaAsFET devices in Micro-X packages such as the Motorola MRF-966 and the NEC NE411 . The circuit is straightforward. I started out with an 8-V supply like TI recommends, but I found the noise figure to be 0.1 to 0.2 dB better at 4.7 V. I measured the noise...

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Arsenide Field Effect Transistors GaAsFETs are used by Anateur Radio enthusiasts to work and experiment in the VHF, UHF and microwave region. Back in 1978, low-noise microwave devices cost as much as 50 or more. Today, the cost has dropped considerably to the 5-10 price range. Texas Instruments recently announced a new line of GaAsFETs costing even less 3.50 each in single-lot quantities. Housed in a Micro-X plastic case, the S3030 dual-gate GaAsFET features a noise figure of 1.1 dB at 1 GHz....