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A Voice Recorder in a Single ChiP! Ibe ISDSingle Chip Voice Recorderincludes every/bingyou need /0 record andplayback a voice message. " needs onty +5VDC /0 use!" The ISO Single Chip Voice Recorder utilizes new analog recording and playback technology that: Estores up 10 20 seconds of natural, human voice • directly drives a 16 ohm speaker with up to 50 milliwatts • needs no crystal reference oscillator eliminates need lor additlOfiallCs These arejust afew ofthe unlimited applications: Create your own contest annunciatorlDXer voice messages. Now all the elements of voice storage and playback reside on a single chip. Simply connect the chip output to your transceiver's microphone input and you are ready to go. Record a transmission on your "analog voice storage (AVS) unit." With a flip of a switch, record and playback rare OX and other contacts. Replay transmissions that are QRM'ed until th e message is understood. Hook up a microphone to the chip and record your own voice messages for repeater identification and annunciation. The chip is nonvolatile. Zero current required to maintain message--ideal for portable applications . "Non-volatile analog storage semiconductor technology is the most significant breakthrough to occur in the industry in ten years" lfiv'd Ilifl President, tSD 1ri46VM To order your ISD chip, return the coupon below or.. . CALL TOLL·FREE 1·800·825·4473 Askfor the CHIP special. Information Storage Devices, Inc. 284 1 Junction Avenue, Suite 204 San Jose, CA 95 134 Shown is the ISD lnnnnnnnnnnnnn 1020 chip and -- - - - - - ...... "'_ 0 " .......... '" - typical external 1020 circuit 10 allow - - _ _ _ N '" N ~ '" N '" N N ~ m ~ ~ ~ 0 _ '" ~ ... .... m ~ ~ single chip analog IU J U IU J U IU recording and playhack. - 0 0 • * • - - - ISO chips eliminate cumbersome and expensive analog to digital and dlg ltal-to-analog conversion steps by offering direct analog input. analog storage and analog output. A single-ehip solution in a 2B·pin DIP package. A system can be built with one chip, a microphone, a speaker, a lew standard cn-me-snert components and +5 volt DC power source. r----------------------------------------, Each ISO chip is shipped with a detailed data sheet Including hook-up schematic. NAME ADDRESS OTY CHIP DURATION PASSBAND COST TOTAL 101 2 12 Sec. 4.5 KHz $61.60 ea. 1016 16 Sec. 3.4 KHz $55.00 ea. o 1020 20 Sec. 2 .7 KHz $50.60 ea CITY ST__ ZIP _ PHONE (__ l _ I Shipping $2.00 I== 8.25%SalBsTax (California Res.) GRANCTOTAL I__ Card' M.C. 0 IIIJIZJ Exp. Date: Visa 0 MAIL COUPON TO: ISD Signature: 2841 Junctlon AvooU/l, Su~e 204 L ~ san JOSQ, CA 95134 0 0 0 0 CIRCLE 73 ON READER SERI/ICE CARD
Number 5on your FHdbackc. rd Portable Frequency Counters Versatile test equipment thatyou can really count on. by Gordon West WB6NOA D o you own a portable frequency counter? Every ham should have one. Even though you might no! do your own internal adjustme nts to your equipment. a portable frequency counter is a valuable amateur radio accessory . Here are some everyday ham radio situations where a portable frequency counter can really come in handy . Let's take a look at a typical day in the life of a counte r. Rntl n ~ You can usc your portable frequency counter 10 idemify sources o f radio frequency interference . This activity is also called radio direction finding. or sniffing . I used mine to pin down the problem of an electric garage door that mysteriously flew open at 5:00 p.m. every afternoon except o n the weekends. The counter registered 151 .62500 as the door swung into action, and a quick check up and down the street revealed a utility truck with a high-band antenna on the roof. Sure enough, the driver' s " at home , 10-1" transmissions at 5:00 p.m. were the cause of the door energizing . A couple of0.0I microfarad bypass capacitors on the door opener solved the problem . W ith some of the newer counters you can actually read the frequency o f a 50 walt VHF mobile signal up 10 250 feet away. With lower power HTs you can usually read their frequency from a coup le of feel away (sometimes from across the room. depending on the sens itivity of the counter) . Do you own a cord less telephone? Trouble wit h interference from a neighbor? Since many people now own cordless phones, and there are only about 10 possible frequencies, you can resolve interference problems by first figuring OUI who ' s o n what channel. Usually the channel number is ma rked on the phone , but that's the firsl th ing to fall offafter the cordless gets a cleaning : Cordless phones only put out flea-powered signals. The counter is able to count out the transponder frequency, and tbe handsel frequency. when held within a couple of inches of the phone's ante nna system. NO! only will you read out the precise frequency nea r 46 MHz or 49 MHz, but you can also tell w hether or nor your set is pulling out the right amoum of power. If you can read the frequency to with in a couple of inches ofthe cordless pho ne 's antenna , power output is normal. If you can't read the frequency wit h the antcn- Photo A. To measure the output frequency of your mobile rigjustplace the coumer near the antenna . nas almost touching , your co rdless phone probably has low batteries , o r low power output. And once you know what frequency your neighbor 's cordless phone is o n, simply relocate your base unit further away from their panicular direction. Fine-Tune Jour UHF Station If you're into 1270 MHz repeaters , 1270 Alta Electronics P .O. Box 8089 Princeton NJ 08543-8089 (609) 275-0220 (600) 526-2532 Beckman Ind. Instrument Product t nv. 3883 Ruffin Rd. san Diego CA 92123 (6 19) 495-3250 MAXTEC B -+- K Precision rnstr. Corp. 6470W. Cortland SI Chicago 11 60635 (312) 889-1448 Oigimax Instruments 7544 Trade S1. san Diego CA 92121 (619)578-7171 John Fluke Mig Co. P .O. Box 9090 Everett WA 98206 (600) 443-5853 MHz mobile, and HT equipment, a portable counte r can really help you fine-rune your sets. You see, equipment at 1270 MHz will ma ny times " age" on frequency . and be as much as 2 or 3 kHz off-channel after a few months of operation. This is because the equipment may use a fundamental crystal still und ergoing the aging process . When I checked out my 1282.4 M Hz repealer system. I found that the repeater had aged up 3 kHz in just under a year, my handheld had aged down a whopping 6 kHz in six months. and my mobile unit was 2 kH z high. Placing this equipment back on frequency is easy- hold the counter within a foot of the opened-up equipment, sample the freque ncy in the slowest rate , and adjust the trimmcr capacitor to put the crystal r ight back on the moncy. How do you know which trimmer cap 10 adjust? It's the one usually in the same can as the crystal, and the technical manual for your equipment normally calls out the exact spot on the board. Use an insulated trimmer-cap wand . affectionately known in the land-mobile industry as the " tw idd le stick." It's usually yellow with a tiny metal blade. CA UT IO N- MA K E SURE YO U A RE TURN ING THE RIGHT TRIMMER. AND NEVER PRESS DOWN ON T HE TRIMMER CAPACITOR . If you fracture the insulating material, you are in big trouble! Cahbrating Your Counter But how do you know your counter is calibrated? Most counter manual s me rely read , " To calibrate the counter. measure a stable signal of known frequency . ,. Hey . wa it a Portable Frequency Counter Manufacturers Bra instorm Engineering Procomm 2948 If.! Honolulu Ave . 1948 Coventry Court La Cresce nta CA 91214 Thousand Oaks CA 91362 (818) 249-4383 (805) 497- 2397 Optoelectronics 5821 N.E. 14th Ave. H Lauderdale Fl33334 (600) 327-5912 orders (305) n1-205O into Startek 398 NE 38th SI. Ft. lauderdale Fl 33334 (600) 638-8050 orde rs (305) 561- 2211 info 73 Amateur Radio Today . November. 1991 15
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