R

If we feed the section of the network with a linear combination of fa and y , the section suppresses y a relative to by a factor of The HA5WH network has the properties that the magnitude of the ratio given in Eq 26 is always less than one for positive frequencies and is exactly zero for < u l (-RC), The first property says that additional network sections can only improve the relative 90 phase shift of the outputs. The second says that we can set the...

Simple Junkbox Satellite Receiver

Use this receiver to monitor the 9600-baud 70-cm PACSATs Single-conversion receivers including direct-conversion designs have received a good deal of attention recently, primarily because of the excellent article by Rick Campbell, KK7B, in August 1992 QST. The receiver described here has been configured for monitoring the 70-cm polar-orbiting PACSATs, and has demonstrated very good performance in spite of the limitations of single-conversion designs. And it has retained the simplicity,...

Phase Shifi Network Analysis and Optimization

Analyzing a phase-shift network shows how its performance varies with component tolerances. The phasing method of single-sideband generation or detection requires two signals with a 90 relative phase shift over the audio frequency range. The phasing method has never been very popular, particularly once relatively inexpensive filters became available. In the future, presumably, digital signal-processing techniques will perform the necessary audio phase shifting or directly generate the radio...

Info

Fig 6 The schematic diagram of one operational amplifier section. reduces the sideband suppression even in the ideal component case to about 35 dB. The HA5WH network takes advantage of cyclic symmetry to give simple design equations and excellent sideband suppression with ideal components. If the cyclic symmetry is maintained, the network is not very sensitive to component tolerances. This means that the components in each of the network sections should be carefully matched. Breaking the cyclic...

A Cvsd Codec System for Your PC

Get started using digital voice with this simple PC add-on card. One of the challenges that Amateur Radio faces in the coming years is how to adapt to the digital communications revolution. While amateurs have embraced digital data communications, largely through packet radio, there still is little use by amateurs of digital voice communications. We seem to be stuck in the analog world of FM repeaters and SSB weak-signal stations. This can't last if amateur communications technology is to...

QEX

Sprague Filter Schematic Diagram

The critical operating characteristic is the 3.5-V bias voltage measured at the MMIC output terminal . A 10-V Vcc, together with 430- 2 series resistors, sets the proper bias to allow the MMIC to operate near its nominal 16-mA current specification Although chip coupling capacitors are recommended, I use standard disc ceramics with little performance compromise, and for someone with poor eyesight like myself they are much easier to use. Two capacitors in parallel reduce...

Line In

And Gate 74ls21 Input

Fig 1 Schematic diagram of the CVSD codec board. U1 74LS245 bus transceiver IC. U2 74LS138 3-line to 8-line decoder IC. U3 74LS08 quad 2-input NAND gate IC, U4 74LS04 hex inverter IC. US 74LS21 dual 4-input AND gate. U6 74LS74 dual D flip-fiop IC. U7 MX-COM MX 70S J CVSD codec IC. U8 TL084 quad op-amp IC. U9 LM386 audio amplifier IC. U10 74LS244 octal bus driver IC. U11 74LS374 octal D latch IC. X1 2-MHz crystal. Not shown are 0.1-nF capacitors from each IC's Vcc pin to ground. trouble to...