Ramsey Electronics FT146 manuale d’uso

FT146 • 1 2 METER FM 5 W A TT TRANSMITTER KIT Ramsey Electronics Model No. FT146 • Dire ct, tr ue FM for excel lent voice and dat a qual it y. • Both Data a nd mi ke audi o inputs • Solid 5 watt RF ou tput - add our PA -146 for 40 watts • Crystal controlled with 146.52 MHz cry stal included • Built-in test points for easy tune-up. A lig[...]

FT146 • 2 RAMSE Y TRANSMI TTER KITS • FM10, FM-25 FM Stereo Tr ansmitters • TV6 Tele vision Transmi tter • Cube TV Tra nsmi tt er s RAMS EY RE CEI VER KI TS • FR1 FM Broadcast Receiver • AR1 A ircraft Band Receiver • SR2 Shortwave Receiver • AA7 A ctive A ntenna • SC1 Shortwave Converter RA M SEY HO BBY K IT S • RB1 Rat Blaster [...]

FT146 • 3 FT146 FM RECEIVER KIT Ramsey Publication No. M FT146 Price $5.00 TABLE OF CONTENTS I ntroduc tion to the FT146 .............. 4 Circ uit Desc ription ......................... 5 Parts List ............................. ........... 6 FT146 Asse mbly Instructio ns ........ 8 Testing and Alignment ................... 19 Power Sup ply Consi[...]

FT146 • 4 INTRO DU CTION Two meter FM has been around for y ears, but never with the popularity that is enjoyed today. In the old da ys, hams snooped around the local tw o-way radio shop in search of an obsolete ta xi cab or police radio. These radios were in the 150 - 174 MHz busin ess band and were easily moved down into the ham two meter band [...]

FT146 • 5 and IC chip) give the equ ivalen t of ab out 130 or more tran sistors an d diodes. And, in addition to 13 inductors, a crystal and the various plus and jacks, there are over 60 capacitors and resistors. Su rely, all that should result in a decent transmitter! You could easily spend twice the money plus hours of time trying to gather the[...]

FT146 • 6 into transm it. There is no need to con trol the voltage to any other tran sistor s since they a ll operate class "C". A class C am plifier draws no current unless it is driven, so there is no need to s wit ch the later stag es on and off . FT14 6 2 ME TE R FM TR AN SM I TTE R KI T P AR T S LI ST Capacitors: ❒ 1 2 or 2.2 pf [...]

FT146 • 7 Inductors and ferrite co res: ❒ 2 Shielded can tunable inductor (marked 007007) [L9,13] ❒ 2 Tunable indu ctor (pink plastic body ) [L5,11] ❒ 2 6 hole ferrite bead core [L1,6] ❒ 2 Small ferrite bead core [L10,12] ❒ 2 Aluminum coil shie ld cans [for L5,1 1] Semiconductor devices: ❒ 1 1N4002 sty le black epoxy diode [D5] ❒ 2 [...]

FT146 • 8 RAMSEY Learn-As-You-Build KIT ASSEMBLY: There are over 200 solder connections on the F T146 printed circuit board. Th at means your work could be 99% perfect and you could STILL ha ve 2 or 3 cold solder points or so lder bridges. Since th is circuit is more sophisticated than a direct-conversion HF receiver or a CW HF transmitter, a beg[...]

FT146 • 9 ❒ 3. Install J2, the subminiature phone jack. Solder all three points. Be gentle and patient in inserting, so as not to damage the solder tabs. ❒ 4. Install R13, 5K trimm er pot. This is the modulation adjustment control. ❒ 5. Install U1, LM358 op-a mp IC chip. In installing the IC, you may w ish to use an 8-pin DIP socket rath er[...]

FT146 • 10 ❒ 21. Install R15, 10K ohm (brown-black-orange). ❒ 22. Install C33, .001 uf disc capacito r (marked .001, 1 nf or 102). ❒ 23. Insta ll R16, 10K ohm, (br own-black-orang e). Time for a breather and progress check. So far, we've built up the audio section of our transmitter, from microphone amplifier to low pass filter to buff[...]

FT146 • 11 ❒ 41. Install R7, 470 ohm (y ellow-violet-brown). ❒ 42. Identify Q1, a 2N3904 N PN transi stor (m arked 2N3904). I nstall Q1 , observing correct placement of the flat side. ❒ 43. Install Q2, anot her 2N39 04 NPN transistor (marked 2N3904).Observe correct placement of the flat side. ❒ 44. Install C27, 15 pf disc capacitor (mar k[...]

FT146 • 12 ❒ 60. Install C21, 4.7 or 5 pf disc capacitor (marked 4.7 or 5 or 4.7K or 5K). ❒ 61. Install L9, slug tune d shielded coil (marked 007007). This coil is part of the first tripler section. It is tuned to the third harm onic of t he crystal oscillator. ❒ 62. Install L13, an other slug tuned shielded coil (marke d 007007). This coil[...]

FT146 • 13 stages of your transmitter. W e recommend that you get them ready for installation before assemb ling the Driver and Final stages. If you prefer to proceed with those stages, winding coils a s you go, that's f ine, too, as long as you realize th at all coil making details are provided in this section. The wire used for L1, 6, 10, [...]

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FT146 • 16 The "legs" o r leads f or inserting L2 , L7, L3 an d L4 sh ould be abou t " long. These coils should sit about 1/8" maximu m above the PC board w hen soldered. ❒ 80. Install L12, on e of the small 3 turn ferrite bead RF chokes y ou wound. Pull it up snug against the PC board and solder. ❒ 81. Install TP2, anothe[...]

FT146 • 17 ❒ 97. Install D4, 1N4148 sty le signal diode (glass body with black band). Observe c orrect or ientation of the ba nded end. ❒ 98. Install TP3, the last test point. Se lect a 1K resistor, R29 (bro wn-b lack- red). Trim back one lead w i re to a length of inch. B end this wire into a small loop as before. Insert the resistor in to t[...]

FT146 • 18 ❒ 112. Install C2, 100 to 220 uf electr olytic capacitor. Be sure to observe polarity - especially with this part since it is directly across th e power supp ly and if reversed, could overheat so fast, so much that it could explode ! ❒ 113. Install D5, 1N4002 style black epoxy diode, observe correct orientation of the banded end. ?[...]

FT146 • 19 coil drastically whenever it is insert ed into the coil. Y ou may use a metal hex key if you are awar e of this ef f ect and are willing to remove the hex key from the coil after ea ch adjustment. Although not re commended, w ith a little patience and sandpaper, a useable tool may be formed from a piece of wood or plastic rod. If you d[...]

FT146 • 20 ❒ 8. Move your meter probe over to TP2, key the transmitter and adjust L5 and L11 for maximum negative read ing. Once aga in, go back and forth between th e two coils. You should get a reading of at least -120 mV. It is very important to tune for th e best peak as this will ensure proper transmitter operation. ❒ 9. You should now b[...]

FT146 • 21 transmitter keyi ng in a rece iver is of some help, but even the sim plest crystal oscillator can send a fi ne signal into your neighbor's receiver. Ideally, yo u have a small RF wattmeter, already inserted in the antenna line, capable of accurately measuring low outp ut power in watts. And it cost you less than what you paid for [...]

FT146 • 22 Amateur radio magazines and handbooks provide a variety of circuits for RF wattmeters and relative field -strength indicators, including methods of using your VOM as an indicating device. CQ magaz ine for March 1990 offers an article by KB4ZGC on how to make a highly accurate yet inexpe nsive dumm y load and w attmeter capable of showi[...]

FT146 • 23 "hum-m-m-, that's not a .001 uf where a 100 pf should be is it?" If there is a problem in getting the m odulation working, a scope or audio amplifier will allow tracing down any pr oblem in sh ort orde r. The microphone audio is amplifier by about 350 times in U1:B. Y ou should see at le ast a volt of audio at the output[...]

FT146 • 24 Here's a handy reference chart for the 5 pin DIN jack PIN # FUNCTION 1 +12 VDC power input 2 Power ground 3 Audio input 4 Audio ground 5 PTT (Push-To-Talk) Audio level required is in the 10 to 50 mV range. PTT requ ires a path to ground of less than 10K ohm s. OTHER ENCLOSURE RECOMMEND ATIONS Your finished transmitter can be insta[...]

FT146 • 25 NOTE ON REP LAC EME N T P ARTS : If you lose or damage parts during assembly or testing, you may, of course, order any needed replacement parts by writing or faxing the Ramsey Electronics, Inc. f actory. Som e of the more common parts m ay also be picked up at Radio Shack or other local parts distributors. Use EXACT values when replaci[...]

FT146 • 26 FT146 PARTS LAYOUT DIAGRAM[...]

FT146 • 27 The Ramsey K it Warranty Ple ase read caref ully BEF ORE cal ling or writ ing in about you r kit. Most prob lems can be solv ed w ithou t co ntac ting the fac tory. Notice that thi s is not a " fine print" warranty. W e w ant you to unders ta nd your ri ghts and o urs too ! All Ramsey kits w ill work if assemble d properly . [...]

FT146 • 28 FT146 2 Meter FM Transmitter Kit Quick Reference Page Guide I ntroduc tion to t he FT146 .............. 4 Circuit Descri ption .......................... 5 Parts List ................ ........................ 6 FT146 Assembly Instru ctions ........ 11 Tes ting and Alignmen t ................... 19 Parts Layout Dia gram .......... .....[...]