Ramsey Electronics SR2 manuale d’uso

Ramsey Electronics Model No. SR2 • Enjoy hours of fascinating international listening us ing just a simple indoor wire antenna • Select portions of the 4 to 19.5 MHz short wave band, easily re-tuned at any time • Smooth varactor diode tuning • Excellent sensitivity and selectivit y • Front panel Volume and Tuning c ontrols • Multi-stage[...]

SR2 – 2 P ARTIAL LIST OF A V AILABLE KI TS RA MSEY T RA NSM ITT ER KIT S • FM10 A FM Stereo Transmi tter • FM100B Profess ional S ynthesized FM Stereo Br oadcaster • FM25B S yn thesiz ed FM Stereo Transmitter • AM25 Synthesized AM Transmitter • AM 1 AM Tr a n s m i t t e r RAMSE Y RECEI VER KITS • FR1 FM Broa dcast Receiver • AR1 A [...]

SR2 – 3 4-19.5MHz SHORTW A VE RADIO Ramsey Publication No. MSR2 Manual Price Only: $5.00 TABLE O F CONTENT S Introduction to the SR2 ............ ............. .............. . 4 What Y ou Can E xpe ct to H ear ........... ........... ....... 4 Shortw ave List ening as a Hobby ......... ........... ..... 5 Circuit Description ...... .............[...]

SR2 – 4 INTR ODU CTI ON TO THE SR2 The SR2 is a single-conve rsion superheterodyne receiver designed specifically for listening to AM broadcastin g stations in the range of 4 to 19.5 MHz. Because of this "super het" design, your favorite foreign broadcasting services will come in loud and clear, wi th pleasing audio sound quality, with [...]

SR2 – 5 • BBC London: an intelligent per spective on w orld aff airs • Radio Canada International: editorial quality similar to BBC • Radio Moscow: powe rful signals, increasingly honest and open • Voice of America: VOA broadcasts ar e "aimed" outside the USA, but if you're in the "path" you'll hear it loud a[...]

SR2 – 6 you, you'll be in a better position to choose a more elaborate receiver. While there are various multi-band portable ra dios available, you can expect to pay at least $100 for a receiver offering a signi ficant improvement over y our trusty SR2. To learn m ore about this SW L hobb y , look for a cop y of "Popular Communications&[...]

SR2 – 7 varactor diode tuning. The varactor (D3) forms an L/C (Inductor/Capacitor) tank circuit with T3. Increasing the vo ltage on the varactor diode with R21 (Tuning Pot) increases the capacitance of D3 thus increasing the frequency output of the LO sec tion. Now that we know the two signals coming into the Mixer stage, both the Fc (receive car[...]

SR2 – 8 RSSI circuit is controlled by the value the feedback resistor R17. If you are commonly using a small antenna and listenin g to weak signals, increase the value of R17 to customize the resp onse indication of D2, the signal strength LED. The final stag e, and the real secret to the sensit ivity of the receiver, is the Automatic Gain Contro[...]

SR2 – 9 Anten na J1 RF I nput & F ilterin g Mi x e r In te rm e d ia te Freque ncy Fi l t er Am p In te rm e d ia te Frequency Fi l t er Audi o (S p e a k er ) SR- 2 Bl oc k Di agra m Local O s cilla to r AGC Dem od Si gna l St r e ngt h LED Autom at ic Gain Contr ol R e c e ive S ign a l St re ngt h I ndi ca t or C1, C2,C3 L 1 ,L 2 Q1 T3, D3[...]

SR2 – 10 PA RTS LI ST CA PA CITO RS  1 10 pF ceramic disc capacitor [marked 10] (C30)  1 47 pF ceramic disc capacitor [marked 47] (C15*)  4 100 pF disc capacitor [marked 100, 101, or 100K] (C5,15*,16 *,17)  1 330pF disc capacitor [marked 330 or 331] (C2)  6 .001µF disc capacitors [marked .001, 102, or 1nF] (C1,3,16*,20,21 ,25) [...]

SR2 – 11 HARDWARE AND MISCELLANEOUS  1 SR2 printed circuit board  2 10K potentiometers (R14,21)  1 DPDT PC-m ount push bu tton s w itch (S1)  1 RCA-type PC-mount jack (J1)  1 Subminiature phone jack (J2)  1 9-volt b attery snap con nector  1 9-volt battery hold-down clamp REQUIRED, NOT SUPPLIED:  9-volt alkaline or heavy-d[...]

SR2 – 12 ASSEMBLY INSTRUCTIONS In ALL PC-bo ard assembl y steps, our word "INSTALL" m eans to do this:  Insert the part, oriented o r "pointed" correctl y , into its holes in the PC board.  If helpf ul, gently BEND th e part's w ire lea ds or tabs t o hold it in plac e, with th e body of the part snugl y against the[...]

SR2 – 13 We will now begin constructing the local oscillator section.  5. Install C22, one of the 10µF electrolytic ca pacitors. Electrolytic capacitors have a right and wrong w ay to be installed. Usually, capacitors have a wide stripe which indicate s their negative lead and the PC board or Parts Layout Diagram w ill show the positive side [...]

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SR2 – 16 jumped ahead and installed T3, w e've got bad news for you). Before this shielded transformer can be installed, its internal capacitor need s to be removed. Looking at the underside of this transformer, you'll see a tubular part, probably white wi th a brown band, somewhat like the resistors in this kit. This is brittle and eas[...]

SR2 – 17  33. Install R2, 22K oh m s [red-r ed-orange].  34. Install R 1, 100K ohm s [brown-black -yellow].  35. Install C24, 1µF electrolytic capa citor. Remember to watch polarity when installing.  36. Install C 5, 100 pF disc capacitor [m arked 100, 101, or 100K] .  37. Install C 4, .01µF disc c apacitor [m arked .01, 10 3, or[...]

SR2 – 18  58. Install C9, 1µF electrolytic capa citor. Check polarity when installing.  59. Install C11, 10 µF electrolytic. Observe correct polarity before installing.  60. Install R16, 270 ohm [red-violet-brown]. PROGRESS SUMMARY Now is a good time to take a break. Examine your work so far checking things such a s component values, p[...]

SR2 – 19  72. Install the battery clamp. Position battery and holder so as not to cover nearby PC board mounting holes. Use the method for securing the clamp that is most convenie nt for you, such as : • wire lo oped through clamp and PC board holes, soldered. • small screws • double-faced adhesive strips • hot-melt glu e  73. If yo[...]

SR2 – 20 provide a ground connection. 4. If an indoor antenna is necessary, simply make it as long as possible and as high up from conc rete floors as you can. 5. W hen installing any outdoor antenn a, BE VER Y CAREFUL not to let your antenna wire come in co ntact with electric power lines. 6. Any antenna wire f or short wave listening ma y run h[...]

SR2 – 21  4. Turn ON the receiver. After adjus ting the volume to a pleasant level, you should hear som e shortwave station s by turning the Tune Control, no matter how any of the adjustable coils h appen to be se t. While listening to any kind of station, w hether broadcast or Teletype, etc., use a small screw driver to adjust the slugs in tr[...]

SR2 – 22 reception. Eventually, you will get a clue as to what general fr equency band you are hearing, because many stations periodically annou nce their frequencies, particularly at sign-on and sign-off times. If you like precision, use a frequenc y counter or calibrat ed receiver to find the SR2's strong oscillator signal, rem e mbering t[...]

SR2 – 23 THE RAMSEY ELECTRONICS C A SE, KNOB & HARDWARE OPTION Your finish ed receiver can be installed in a variety of enclosures of your own design and cho osing. You might be p lanning to combine several Ra msey circuit kit boards in a single enclosure . Use of the inexpensive and attractive Ramsey case and knob kit will give your unit tha[...]

SR2 – 24 SAMPLE SHORTWAVE LOGGINGS Freq Country Notes/Contributor (MHz) 4.30 PERU ballads, huaynos, brief annmt, TC partial ID, tnx 4.31 DIEGO GA oldies, good sig 4.38 PERU long talk , rel talk, choir, poor 4.40 BOLIVIA romantic vocals, poor 4.72 S VIETNAM VT pop tunes, YL anncr, instl mx 4.72 MYANMAR soft vocals, ID , nx 4.78 GUATEMALA ID, nx 4.[...]

SR2 – 25 SAMPLE SHORTWAVE LOGGINGS Con’t Freq Country Notes/Contributor (MHz) 18.96 SW EDEN "S w eden Today", special on Nobel priz es 18.96 SWEDEN "Sweden To day", article on burden of military spending on developing c ountries 18.96 SWEDEN Cinema Africa Film Fest being held in Stock holm 18.98 USA relig m x, sermon, ID[...]

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SR2 – 27 The Ramsey Kit Warranty Ple ase r ead car efu lly BEFO RE call in g or writi ng in a bout your k it. M ost pro blem s can be sol ve d without contacti ng the f actory. Notice that thi s is not a " fine print" warranty. We want you t o unders tand your righ ts and ours too ! All Ramsey kits will w ork if assemble d properly . Th[...]

SR2 – 28 SR2 S hortw ave Rece iver Qui ck Ref erenc e Pag e Guid e Introd ucti on to the SR2 .. ........... ......... . 4 What You C an Expect to Hear ............ 4 Shortw ave Listeni ng as a Hobby ......... 5 Circuit Description .. .............. ............. .. 6 Parts L ay out Diagra m ........... ......... ..... 8 Parts List .............. [...]