QEX

Figure 22 shows one example, but some others have been published. We will examine a few to see what is possible over a range of f D. The NRAO Scalar feed in Figure 22 was recently replaced27 with a large dual-band feed that is 5.2 X in diameter at S-band. Figure 30 is a graph of the S-band efficiency with this feed, which is best at an f D of about 0.6. However, the 85 foot dish has an f D 0.42. The goal in radio astronomy is lowest noise, so the feeds are optimized for best G T,...

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First, it is often quite efficient to work with half elements when modeling Yagis, because the assumption that you have a symmetrical antenna enables the software writers come up with a programs that run faster and handle bigger antennas. Thus, the taper schedule specifies just half an element, although this may be a poor way to actually build an element. Also, the schedule doesn't include any overlap required to actually join the elements it's just the electrical model....

1998 Qex Build A High Voltage Transformer For A Low Cost

Looking for HV supply parts A few dead microwave ovens may supply all the parts you need. Hot from the kitchen, here's a full-course supply for power-hungry vacuum-tube amplifiers. Have you had thoughts of building a high-power amplifier or resurrecting a used bargain amp I've thought about such a project for a long time. Initially, it seemed like a good idea when compared to the price of a new amplifier. After researching the cost of power-supply parts, however, I began to have second...

R

Fig 10 Audio amplitude and phase-shift adjuster. phase shifter or the quadrature hybrid for connection to an RF port. Don't use a tee network because its inductive output which was advantageous for driving an LO port can forward bias the mixer diodes during portions of each LO cycle when there is little, or no, diode current from the LO. The big disadvantage of placing a phase shifter in the RF path is that you lose the benefit of the DBM's insensi-tivity to LO-drive level. Thus when you change...

Reprints From The Rsgb Microwave Newsletter

Microwave COMB Generator for Receiver Testing, Andy Talbot, G4JNT Power Conditioner for the Qualcomm 10 GHz One Watt PA MODULE, Andy Talbot, G4JNT A Novel Dish Feed For 10 GHZ, Jean-Robert, F1DFY The Chaparall Scaler Feed Horn, Peter, G3PHO TESTING Antenna Gain Measurements, Twenty-Second Eastern VHF UHF Conference Noise Figure Measurements, Twenty-Second Eastern VHF UHF Conference REPRINTS FROM QEX Mounting RF Connectors, Zack Lau, W1VT Noise Measurement and Generation, Paul Wade, N1BWT...

Blj Electronics Amplifier

Mobile and Portable Operation of Voice Mode Satellites, Chuck Duey, KI0AG WATOO An Internet Access Software to a Satellite Tracking Station, Marc Normandeau, Steve Bernier, Jean-Marc Desbiens and Michel Barbeau Satellite Technology for Newcomers The Weather Channel Model, Rich Moseson, W2VU They Never Told Me Not To An Innocent is Seduced by Centimeter Waves, Laura Halliday, VE7LDH An EZ-Sat Proposal, Frederick J. Winter, N2XOU, and Ken Ernandes, N2WWD An Object Oriented Approach to Automatic...

RF Phase Shifters for Phasingtype SSB Rigs

Here are four popular methods to achieve quadrature 90 phasing X 4 transmission line, pi network, tee network and quadrature hybrid. Learn about their strengths and weaknesses how and where to apply them. There has been a resurgence of interest in the phasing method of single sideband generation and reception as evidenced by recent articles and papers.1- 2'3 The portion of such SSB rigs that seems to be least well understood is the RF phase shifter connected between the local oscillator and the...

The American Radio Relay League

The American Radio Relay League, Inc, is a noncommercial association of radio amateurs, organized for the promotion of interests in Amateur Radio communication and experimentation, tor the establishment of networks to provide communications in the event of disasters or other emergencies, for the advancement of radio art and of the public welfare, for the representation of the radio amateur in legislative matters, and for the maintenance of fraternalism and a high standard of conduct. ARRL is an...