Ramsey Electronics QRP20 manuale d’uso

QRP-20 • 1 20 METER (14MHz) CW TRANSMITTER Ramsey Electronics Model No. QRP20 THE RAMSEY QRP20 IS AN AMAZING PERFORMER THAT W ILL WORK THE W ORLD ON ABOUT A W ATT! FOLKS OF ALL AGES HAVE SUCCESSFULLY BUILT AND ENJOYED THIS EASY, FUN KIT. • Ideal for portable or trav el fun • VCXO design allows up to 8 - 10 KHz of tuning about the cry stal fre[...]

QRP-20 • 2 RA M SEY TRA NSMIT TER KIT S • The “Cube” MicroStation Transmitter • FM2 5B S ynt hes iz ed FM Tr ans mi tte r • FM100B Stereo FM Transmitte r • AM 1 AM Tr a n s m i t t e r • A M25 S ynthesized A M Transmitte r RAMSE Y RECEI VER KI TS • FR1 FM Broa dcast Receiver • AR1 A i rcraft Band Rece iver • SR2 Shortwa v e Re[...]

QRP-20 • 3 QRP20 20 METER CW TRANSMITTER KIT Ramsey Publication No. Q RP20 Price $5.00 TABLE OF CONTENTS Introduction to the QRP2 0 ............. 4 Understanding Power Level s ......... 5 QRP20 Circuit Description ...... ....... 7 Block Diagram ............... ............. .... 8 Parts List ......... ................. .............. 9 Schematic [...]

QRP-20 • 4 INTROD UCTION: Most "QRP" transmitters are one-of-a-kind experimental circuits w hich tak e some patience and fine-tuning to get clea n keying and satisfactory perfo rmance. Mos t QRP building pr oj ects presume either unlimited radio junkboxes with all the right coils and capacitors, or that you have a lot of time on your ha[...]

QRP-20 • 5 If you're studying this manual before deciding to try this Ramsey "QRP" transmitter project, perhaps the following discussion will be helpful to you. The purpose of this m anual is to he lp you constru ct this Ram sey Electronics 4- stage, variable-frequency C W transmitter efficiently and successfully, no t necessarily [...]

QRP-20 • 6 start at the proverbial "30 db. over S-9" an d work itself down to S-1 for reasons that will become obvious. S9+10 db. 1000 watts output S9 100 watts ou tput S8 25 watts output S7 6.25 watts output S6 1.56 watts output S5 .39 watts ou tput We can see that it becomes easy to play games with such numbers. For example, an RST of[...]

QRP-20 • 7 On the other hand, if you hear a 1000 w att station producing a moderate signal such as S4 or S5, you can reasonabl y assume that you will not have a lot of luck over that path right now with the th eoretical S1 signal level of your QRP transmitter. While these figures also can be used to show how nice it is to have a power amplifier a[...]

QRP-20 • 8 Q3 is a Cl ass C RF am plif ier that am plifies th e RF output of Q2 t o the f inal RF power output level. L6,C17 and C18 f orm a low pass filter (Butter worth) to m atch the output of Q3 to the antenna and reduce harmonics to acceptable levels as specified by the FCC. When the keying line is closed, Q4 c onducts +12VDC to the oscillat[...]

QRP-20 • 9 PARTS SUPPLIED WI TH QRP20 TR A NSMITT ER KIT: CAPACITORS:  1 47 pf capacit or (C6)  2 68 pf capacitor (C2,C12)  2 220 p f capacito r (mar ked 220 or 221) (C 17,C1 8)  1 330 p f capacito r (mar ked 3 30 or 33 1) (C 3)  11 .01 uf capacit ors (marked .01 or 103 or 1 0 nf) (C1,4,5,7 , 8,9,1 0,13,14, 15,19)  1 100 to 220 [...]

QRP-20 • 10[...]

QRP-20 • 11 QRP20 PA RTS LA YOUT DIAG R A M:[...]

QRP-20 • 12 "LE ARN- AS-YO U- BUI LD" T R A NSM IT TE R ASSEMBLY ST R A TEG Y: As you can see in examining the circuit board and components, there is a bit more to this transmitter kit than soldering a few parts and putting a signal on the air. So that you don't spend extra time "troubleshooting" instead of getting on the[...]

QRP-20 • 13  5. Insert and solder R1, the 10K tuning po tentiometer.  6. Insert and solder S1, pushbutton sw itch. Carefully select, inse rt and solder the following components in the order given in the following steps. Check off each step as completed.  7. C16, 100 to 220 uf electrolytic. Electrolytic capacitors are polarized, which me [...]

QRP-20 • 14  18. Install R14, 10K ohm s [bro wn-black-orange] .  19. Install Q4, be sure to orient its flat side correctly as shown .  20.Install C15, .01 uf (marked .01 or 103 or 10 nf). So far, here's what we've accomplished. First, w e've got over a third of all the parts soldered onto the board, which shou ld make you [...]

QRP-20 • 15  29. Install C3, 330 pf (marked 330 or 331).  30. Install R6, 470 ohms (yellow-violet-brown). With th e above compone nts installed corr ectly, the three ho les for Q1 sho uld be clearly apparent. Make sure Q1 is co rrectly identified as a 2N3904.  31. Install Q1, 2N3904. Orient its flat side correc tly .  32. Install C5, [...]

QRP-20 • 16 CRYST A L OSCILL A T OR TESTI NG: ◊ Connect a key , keyer or m omentary switch to J3. ◊ Connect + 12VDC to power conn ecto r J4. Note tha t the CENTE R connection is the positive (+) side. ◊ Tune a nearby receiver to the anticipated crystal frequency. ◊ Make sure that S1 is set to the correct crystal position. Keying J3 should[...]

QRP-20 • 17  46. Install C14, .01 uf (marked .01 or 103 or 10 nf).  47. Install C9, .01 uf (marked .01 or 103 or 10 nf).  48. Install D1, 1N4002 (large black epoxy body), notice placement of banded end.  49. Install L4, 100 uh indu ctor [brown-black-brown-silver].  50. Install R8, 47K (yellow-violet-orange).  51. Install C7, .01[...]

QRP-20 • 18 14 to 15 volts DC. The easiest method is to place t wo fresh "D cells" in series with your power source, if a full 13.6- 15 volts DC is not available. If your supply vo ltage is in the 11-12 volt range, you can expect a 200 to 250 ma current flow and about one-half watt of the RF output power. W ith a solid 14 to 15 volt sup[...]

QRP-20 • 19 Please remember, though, that a flashlight bulb does NOT present the proper load impedance to the transmitter output, so theoretical calculation s based on the bulb`s rating can o nly be approxim ate. For exam ple, the PR-4 at full brilliance presents only an 8.2 ohm load to the transmitter. If ANY flashlight bulb lights up when conn [...]

QRP-20 • 20 is the Ramsey CW- 7 CMOS Keyer, with built-in side tone. This transmitter is an ideal travel comp anion to the growing number of portable shortwave broad cast receivers which fe ature digitally s ynthesized tuning, memories and other features , provided that a BFO for CW -SSB reception is one of the features. In most cases, transm itt[...]

QRP-20 • 21 FIN A L CONSI DER ATIONS: Our earlier discussion of how a watt of RF output can indeed offer satisfy ing communications has seve ral presupposition s: 1. A resonant antenna (dipole or quarter-w ave vertical) 2. Good quality coaxial feedline and connectors 3. An effective earth ground We cannot expect good results from low levels of RF[...]

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QRP-20 • 23 The Ramsey Kit Warranty Please read carefully BEFORE calling or writing in about your kit. Most problems can be solved wit hout contacting th e factory. Notice that thi s is not a " fine prin t" warranty . We want you to und erstan d your righ ts and o urs too ! All Ramsey kits w ill work if assembl ed prope rly. The ve r y [...]

QRP-20 • 24 20 M ETE R CW TR AN S MIT TER KI T Quick Re ference P age Guide Introduction to the QRP20 .............. 4 Understanding power levels ........... 5 QRP20 Circuit description ....... ....... 7 Parts list ........ ............. ................. .... 9 Schematic Diagram .................... .. 10 Parts layout diagram .................. [...]