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PIN diode switches show up most often in low-level applications where inexpensive diodes can be used without worrying about poor isolation or loss characteristics. While PIN diodes are often used in a simple SPDT configuration for low-level switching, a series shunt configuration is the best bet for TR switching. With the proper diodes, a series shunt TR switch can exhibit isolation greater than 30 dB and losses of only a couple tenths of a dB. See Fig 3. Table 1 details some of the relays...

QEX

One of the most complex operating controls of our high-performance mobiles. You don't have to sacrifice performance to gain simplicity in your mobile operation. Yaesu's FT-211RH Series gives you top-of-the-line performance on the 144,220,440, or 1260 MHz bands in sophisticated, microprocessor-controlled mobile packages. With controls that couldn't be more straightforward and easy to learn. Which means greater driving safety without performance compromises. In fact, if vou own one of our FT-23R...

P

Fig 3 Free-space horizontal path loss, L, between two antennas separated by distance, d. pecially if one of their own services might be involved. A 2-m hand-held transceiver that I converted from the commercial high-band service frequently picked up paging messages and QSOs over the local repeater. The interference was heard on all channels, and had the character of A-B IM. Some detective work revealed the mixing signals were on 158.43 MHz (a local, industrial paging service) and 146.73 MHz...

Surviving in the Intermod Jungle

By Mark Bacon, KZ9J 2205 File Dr Decatur, IL 62521 live on top of a gentle rise, a good location for transmitting and receiving signals. I also live in the shadows of two broadcast towers an AM antenna 300 yards west of my back yard, and a commercial FM amateur site less than a mile to the east. My station is subject to intermodulation interference (intermod or M), and ( can quickly tell from my operating position whether a receiver has a strong front end and good spurious rejection. If the...

Qex November Ad Index

Advanced Computer Controls, Inc. 20 Madison Electronics Supply 20 American Radio Relay League Mirage KLM 19 Cov II, Cov IV, 20 P.C.Electronics 18 Down East Microwave 20 Yaesu U.S.A. Inc. Cov III Henry Radio Stores 17 P.C. ELECTRONICS 2522 PAXSON LANE TOM (W6QRG) & MARY ANN (WB6YSS) O'HARA P.C. ELECTRONICS 2522 PAXSON LANE TOM (W6QRG) & MARY ANN (WB6YSS) O'HARA ARCADIA CA 91006-8537 USA _(818) 447-4565 electronics 33cm (902-928 mHz) ATV SYSTEMS Get on the new band with these modules, snow...

Four Great Conferences

Packet Radio Enthusiasts meet in California. VHF UHF and Microwave Enthusiasts gather in Texas, Colorado and Pennsylvania Anyone who says that experimentation and building equipment by radio amateurs is a lost art should take a long hard look at these proceedings books They are available from many dealers or directly from ARRL for 10 each. Please include S2.50 3.50 for UPS to cover shipping and handling of each order. Papers submitted are in camera-ready form, are unedited and are solely the...

Measurement Of Antenna Impedance

By Peter Dodd, G3LDO, and Tom Lloyd, G3TML Measuring antenna impedance with a simple RC bridge is one way to find out what is happening in a transmission-line system. This article is based on Strandlund's 1965 QST article about measuring complex impedance. This modern method, however, uses computer programs to simplify the task. A 1200-Bit s MANCHESTER PSK ENCODER CIRCUIT FOR TAPRTNC UNITS - 10 The ripple counter found in previous encoder circuit designs has been replaced with a synchronous...

Bits

New Switched-capacitor Filters Make Their Debut Each of eight filters in the XR-1000 family is a fourth-order, low-pass switched-capacitor filter. These components provide different responses and clock-to-corner ratios to increase and vary the number of possible applications for which they can be used. The design requires no external resistors or capacitors to create the filter function. A single external clock is all that is required to position the corner frequency of the low-pass filter. If...