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"'12V "' 12-24V .60 10K lOOK .I IN34 1"34 4 .7K 2N2925 r .0 0 5 .0 0 $ lOOK lOOK .1 2N2925 to get the value of C I , then multiply th e resu lt by 10 to det er min e th e value of CZ. For thos e who .are mathematically lazy , 88 mH , 2 J.lF and 0 .22 J.lF will give you approximately 100 0 Hz, Use at"least 10% mica capacitors for C I and CZ; otherwise, you will have stability pro blems. The transistor can be just about any general purpose NPN yo u have around. Th e out put sho uld be connected to your mike in pu t , and the con tro l adjusted to give about 5-10 kHz deviation. Decoder The decoder is a twin-tee circuit followed by a d o amplifier. Th e input level control can be brought dow n to give yo u a ban dwi dth as narrow as ±30 Hz! The two inp ut diodes clip th e incomi ng signal to a max imum value of 0.2V pea k to peak; they can be any general-pu rp ose germaniums. The ou t put of the decoder is rectified and fed to a standard dc amplifier; th e relay in the collect or of Q2 is th e on e 1 had in my jun kbox, so you might have to experiment with th e value of R S ; the relay sho uld close at abou t 6V and 6 - 10 rnA. The in put should be connected to the discriminator output of the receiver. Th e input pot sho uld be set up so that the relay closes reliably every time the encod er is keyed ; it helps to have a frie nd stay home to adjust it while yo u drive around . A 30-50 IJ.F capacitor can be conne cted aft er the diode to give a turn -on time delay of 3 to 5 seco nds ; this will not be applicable to sta ndard repeaters, but it could prove quit e benefi cial for rem ote co nt ro l fo r those o f you who have friends wit h strange sen ses of humor. Wit h the capacitor in the circuit, an audio generator sweeping your frequency will not trip the decoder. A heavy du t y relay mu st be connec ted at th e output, since the contacts on a sensitive relay are rat ed at only a couple of watt s; a ratc he t relay can also be used for lat ching on- off operation . One final no te : If you are going to use the system through an o pen re peater , be discreet. It is very annoying for people monitoring the fre que ncy to hear tone bursts coming thr ough ; and fina lly, be sure to 10 eac h time you use the un it. ...VE2BZ K 38 73 MAGAZIN E
Here's The Mobile FM AFTERBURNER Delivers 50 Watts 01 Punch on Z Meter FM , The Varitronics PA-50A is a completely solid state Class C RF amplifier designed specifica lly for use in mobil e amateur FM applications. Internal RF switching makes the PA-50A useablewith any amateur FM transceiverwith 10 watts" output. Balanced emitter devices are employed which are completely insensitive to high VSWR or even no load conditi ons at its output. This ha ndsome and ru ggedly built amplifier is styled like the IC-2F transceiver, featuresacalibrated output meter and is supplied with mobile mounting bracket and DC cord. For the big signal on FM, try it! SPEC IFICATIONS *Orive Requirements ... 12 Watts Maximum 5 Walts Minimum RFOutput 50 Walts - less . with lower drive or input voltage Power Requirements 13.5 VOC @5 Amps Impedance 50Ohms In/Out Frequency Any Portionof Amateur 2 Meter Ba nd SpuriousProducts 50DB Down Dimensions 6" X7" X2" Manufa ctured by Varitronics . .. still the leaders in quality amateur FM equipment. See it at your de alers. VARITRONICS INCORPORATED 2321 EAST UNIV ERSITY DRIV E · PHOENIX , A R IZO NA
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Page 3 and 4: CONTENTS where. Then carne the day
Page 5 and 6: for ~ bo ut 10 years, has know n Ro
Page 8 and 9: :l Caveat Bmptor?r ~~~~~.~ ~.~~ *r.
Page 10 and 11: BOOKS I ADVAN CED CLASS STUDY G U I
Page 12 and 13: Irving M. Gottlieb W6HDM M~W 931 Ol
Page 14 and 15: situ ated on a PC board (Fig. 4) di
Page 16 and 17: See your DEALER for DRAKE products
Page 18 and 19: Practical circuit applications usin
Page 20 and 21: INPUT )1 c I SO MHz 1N4381 IOO~ 450
Page 22 and 23: The Mos t Powerful Signals Under th
Page 24 and 25: CA 3028 J.lL 923 '" 4.7 K ., 680 4
Page 26 and 27: K
Page 28 and 29: Theodore Cohen W4UMF 8603 Conover P
Page 30 and 31: ~ ~ Installation of the switch and
Page 32 and 33: A ~Sy CQ, CQ, CQ, t his is K3FEN, R
Page 34 and 35: Messy and m ickey mouse, bu t wh en
Page 36 and 37: The tuning indicat or shown in Fig.
Page 38 and 39: Being qui te activ e on two me ter
Page 42 and 43: ON.. EFFICIENCY ORGANIZATION and MA
Page 44 and 45: Bill Hoisin gton K 1eLL Far Over F
Page 46: installation of on e or more low-no
Page 49 and 50: STEP UP TOTELREX Professionally Eng
Page 51 and 52: " 4 ~ O Y " 4 ~ OY ( I U 6 2 11 0'
Page 53 and 54: etter than the "Hot-Water 100 " ...
Page 55 and 56: y Ken W. Ses$ion~ K6MVB DU LD A 8 .
Page 57 and 58: Motorola HEP Semiconductor Devices
Page 59 and 60: see the A1ann for the best in USED
Page 61: esults. The transmitter adj ustme n
Page 65 and 66: What Is An Amplifier? Several acres
Page 67 and 68: When it comes to grea t used mo bil
Page 69 and 70: of am plifier o pera ting con ditio
Page 71 and 72: New advanced 4-band, Communication
Page 73 and 74: LI NEAR NON-LINEAR Radio Amateurs R
Page 75 and 76: 1. T he amp lifier is adjusted to o
Page 77 and 78: many do not) you can either speak a
Page 79 and 80: SOLID STATE ENCODERS for quick and
Page 81 and 82: WHEN IT COMESTO ANTENNA SYSTEMS...I
Page 83 and 84: Richard Tashner WB2TCC 163-34 2 1 R
Page 85 and 86: A. E. McGee, Jr. K5LLI 281 5 Materh
Page 87 and 88: John G. Harder W5QKO/AI4QKO 6200 A
Page 89 and 90: The LOUJ-OhTn JJleter ALL RESISTORS
Page 91 and 92:
Photos I and 2 show the meter built
Page 93 and 94:
powers of ove r 100W across the ban
Page 95 and 96:
,r-"--'.N=;;EED AN ] CRYSTALS? PHON
Page 97 and 98:
4.000 BIT MEMORY D $8.50 from IBM C
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