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73Amateur • 0 RadioToday ICOM READER SERVICE GIVEAWAY Ju st fill out the Reader Service card and send it in. You 'll receive free product information from our advertisers , and one lucky reader will win a great prize from ICOM. THIS MONTH'S READER SERVICE PRIZE ICOM IC-2SAT ICOM's expertise in miniaturization has resulted in another remarkable handheld, the IC-2SAT. • 5Watt PowerOulpul The 1(;.2SAT delivers afull 5 wattsofoutpul power at 13,8V DC. • Buill-In NiCd Batteries Whenthe internal batteries are exhausted just clip 00 oreotme optional battery packs and keep on operating! • 48 Memory Channels Each memory and callchannel stores all information required for repeateroperation. • Quick Tuning Control Frequencies or memory channels can beeasily selected with the built-in keyboard or tuning control knob. • OTMFCode Memory 10 DTMF memory channelsstore cote 15 digitseach. Excellent for autcoachmq! • B ui~·ln Clock The IC·2SATis equipped withaza-noursystem clock withtimer function. • External DC Power Jack The IC-2SATcan beconnecled toan extemare-ts vo~ DC power supply directly. The ICOM IC-2SAT includes a variety of other features like convenient scan function s , priority watch, memory masking, memory t ransfer , tone squelch an d so much more. Batt ery packs and a battery case, chargers, headsets and a wide selection of other options are also available. ADVERTISERS Due to a printing error, the Man::h and April Reader service cards will be dated " February 1991 ." R.S.II page R.S.II page R.S,II page 109 A & A Engineerir.g . . 71 164 Ace Commun>cationsot IndianafKIlis se 83 Ace Systems . ,... 71 65 Advanced Electronic Appl>cations . , . 13' 253 Alabama Amaleur Eleclronk:s. . .. 65 67 Alinco ElecTronics , , , 33 194 All Elecl,on>csCorfKIration " 39 • Amateu, Electmnics Supply , .. 31" 4 Amidoo Associates , 69 89 Antennas West. . .. , , 34 5 Antennas West . , 47 107 Anlennas West , . , 87 90 Anlennas West , ... , ,... , 71 138 Anlenna s West , 17 135 Anlennas West , 81 236 Antennas West , . 71 16 AwonCorporation . . . . " .. , 25 243 AXM, Inc. .... 47,51 21 a a a.tee. ,65 262 Baitey Counlry Store . " . " 28 53 Barter & Williamson ... , , .. 53 41 Barry Electronics CorporahOfl , 23 42 Bilal Company, ,... , . . . . , 65 176 Bird Electron>cs . . . . 41 197 Brainstocalion Concepts, Inc, 69 121 Communications Electronic . ,..... 27 10 Commun>cation Specialist, 16' 146 Crea t i~ eControi P,oducts , . 81 29 CustomEmbroklery .. ,... , . , .81 • DaytOfl Hamvention . , 37 256 Delta Research . . . , 58 257 Delta Research 49 • Down East Microwave 81 185 Elect'on icEngineering , 47 128 Electronics Book Club .. , 63 8 Elktron>cs .. . 51 • Enginee,ingConsulting. .,. 79 280 Excellent Te
ABOVEANDSEYOND CL Houghton WB61GP San Diego Microwave Group 6345 Badger Lake Ave. San Diego CA 921 19 Microwave Beacons To round out last month's column on waveguide mixers and microwave tormulas, this month I'll covera typical 10 GHz microwave beacon . By changing the RF source and antenna, you can adapt the plans lor this beacon to other microwave frequencies. Unlike beacons on lower frequencies such as 6 meters, microwave beacons are not put up only to reveal CUfrent propagation conditions. If you heard a 6 meter beacon clearly, you would rush to the shack and start operat ing, looking for contacts on that band. But it you heard a microwave beacon from some remote location, you would, instead, gel busy on the phone to set up contacts. The m icrowave beacon no t only alerts you to band conditions, but also serves as a piece of test equipment. During contests, the microwave beacon transmits a signal that stations can use to check antenna alignment and 10 prove that their stations are functioning normally. Most importantly, the microwave beacon provides a reference signal 1000al amateurs can use as a transfer frequency standard. This way, the custodian of the beacon can verify frequency as accurately as he can (in the band , of course) and setthe standard, Frequency and Offset In any large group, someone can come up with a best metncc of determining frequency either by wavemeter or frequency meter. The method used doesn't make any difference. When you have lh is type of system in place. all other stations can set their equip- VHF and Above Operation mentto copy the beacon. You can set your system's frequency to either sideband mix product, offset by your IF frequency, This offset is determined by whalever IF frequency you are using. One standard is 30 MHz. For example. if the transmilter is on 10.250 GHz, you can copy on either 10.220 or 10,280 GHz , since both frequencies are in the 30 MHz offset due to the IF frequency. When all local stations are copying the same beacon , frequency determination problems decrease , Until most amateurs in an area can agree on [ust where 10,250 GHz is, it can be a large slumbling block. Even if a beacon is slighlly off-frequency, everyone in the local area using the beacon will be attected the same . What matters is that all stations in a local area know where the beacon is and use it. Antenna Checking With a microwave beacon , you can check your antenna direction pointing. and test the sens itivity of your receive system. Microwave antennas. especially dish types, can have beam widths of 3 to 4 degrees or less. This makes accurate dish aiming very lmportent. Copying a local beacon , you can verify direction (compass bearing) and vertical position. This helps elimi· nate one more wobble in the system , Sensitivity can be verified by comoaring results to past tests . or by placing an attenuator in the system for further tests. Useof a beacon has proved to be a valuable asset, lelling you maka quick assessments of system performance . Quick varificalion can be everything during contest weekand. See the beacon schematic in Figure 1. The Beacon System Construction of a 10 GHz beacon is quite simple. All you need Is a source of RF, such as a Gunn oscillator, an teen- Photo B. "All mode " (CW, SSB, and NBFM) 10 GHz transverter constructed by VK2ALU Oscillator chain andamplifierisa G400K design feeding a X9 SRO(step recovery diode) multiplier. The 10 GHz mixer section is a G3JVL design (image reject mixer) with output on 144 MHz. The antenna selected for beacon operation must be compact, high-gain, and omnidirectional to be of general use What fills the bill is Ihe near amtification system, and an antenna, The CW identification system , described in the June 1990 column, is just a simple TTL kever with an EPROM loaded with your calls ign. The unit repeats what is loaded into the EPROM over and over again, reseWing after each message. The aud io output from the keyer is coupled to the adjust terminal of a Gunn oscillator po wer supply, imposing wideband FM modulation on the Gunn oscillator. In most beacon setups the power supply (unregulated DC) is remote to the actual beacon , with the Gunn oscillato r/power supply modulator and kayer located within a common housing with the microwave antenna. The keyer is about the size of a pack of cigarettes and the Gunn oscillator is a compact structure about an inch and a half square. A short section of plastic drainage pipe is often used to house the enti re system. The Beacon Antenna ." , ~", .,.. to.' "0 '" nidirectional waveguide slot antenna. For 10 GHz, a waveg uide slot antenna is less than a foot long; 6 slots (on each sitfe ot the waveguide) exhibits 10 dB gain. See Figure 3 for construction details, The top of the antenna is shorted with a machined brass insert that closes off the top of the waveguide. A single waveguide flange connects the antenna. The Gunn oscillator may be directly connected to the antenna, or a magnetic isolator may be placed between the antenna and the Gunn oscillator. The isolator helps reduce pulting on the Gunn oscillator by allowing RF to flow freely in one direction, which provides high loss to refl ected RF (VSWR). The slots in the waveguide are verncal, in the same plane as the length of the waveguide. The radiated RF is hori· zontally polarized. To receive horizontally polarized radiation, your receive waveguide must be vertical (the longer opening of the waveguide). Having you r waveguide vertically polarized means having the long opening Of the waveguide horizontal. If this sounds confusing• just remember the rule: The .......... • J '"' "'E'" o. w' _,. ' CO" ~ r:0'" ." ..' ' UO"0'< r• " 00 ' ,.'IDE' '''''''''.m ..''... / "00"" '"'' ·"" '''''''''' wOO'''' ' '0.·.- " • .". H"" '0" n • "" uo." ,",,,tEo '" ...00. "0' '."0'''' -- .,,'." ..", "''''0''' .. 0< " ... , , ... . . L '0 ''''0' ,""w,' '0."0' ''''''''0 ""0" .,..'" "'"" ,. '"'" .. '-0"' "u. '" " 'CE " " . " , ' 0 """'"",,. .. ', ...000 ""'11.' PhofO A. Lyle PaNson VK2ALU of WolIongong , Australia. operating a 10368 MHz transceiver on SSB, testing over 80 km to VK2ZAC (who can receive on SSB but only transmit on NBFM). Note sighting telescope mounted below dish. A Gassegrain subreflector feed is used allowing more effiCient illumination. The 20 inch dish is a searchlight reflector. Figure 1. 10GHz beacon showmgCW IO'er andpowersupply. Regulator/modulator audio from fO'er feeds to adjust terminal ofregufator for modulation on input on regulator output voltage to Gunn osciflalor, which produces high quality wideband FM on 10 GHz (See " Above and Beyond" in the June 1990 issue of73 for CW ID delails). 73 Amateur Radio Today . March,1991 73
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I • • Hams in Space!
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MFJ, Bencher and Curtis team up to
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THETEAM PUBLISHER/EDITOR Wayne Gree
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