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Model 1254 Receiver
TROUBLESHOOTING GUIDE

This section presumes that the receiver has been working and that you now suspect
a problem. Problems encountered DURING kit assembly phases should be corrected
before progressing to the next assembly phase.

1. Look for the simple and obvious first:

Power supply or batter connection problem

Blown power supply fuse
Broken antenna coax connection
Defective headphone or speaker cable

2. Many typical problems can b e resolved by consulting the Troubleshooting
Chart on the following page.

3.

Diagnosis of other possible problems is done best by reviewing the Circuit

Description (Reference Section) and the progress tests after each kit assembly phase.
Selection of correct component values is very important, which is why double-
checking is recommended throughout the building process.

4. If you are not the original builder of the kit, we suggest the following procedures
in this order:

&KHFNIRU9'&DWWKH/'³ORFNGHWHFW´WHVWSRLQW

(Lack of LD voltage indicates PLL or VCO problem.)

Perform the voltage checks including VCO alignment per page 37

Explore any circuit section showing drastically

different voltage readings.
Review the Progress Tests at the end of each Assembly Phase.
Examine boards for cold solder joints, solder bridges,

damaged hookup wire jumpers. Touch up as needed.

Review correct polarity or orientation of all parts.

If none of the above helps, it's time to review the Component Index and kit assembly
phases to see if any incorrect part values were installed. Yes, check every part!

5. Parts Replacement

. The most likely cause of component failure in this circuit

design would be incorrect values installed for some other component(s). Therefore
replacing a bad part should also include the discipline of checking the values installed
for parts immediately associated with that failed component. Also, if you find a
wrong value installed in one place, you should wonder where the correct value was
installed.

Use care and

PATIENCE

in desoldering parts. The plated-through holes make it a

FKDOOHQJHXVLQJD³VROGHUVXFNHU´RU³VROGHUZLFN´EUDLGLVUHFRPPHQGHG

1254

±

Reference - 36

Содержание SSB-CW-AM

Страница 1: ...KIT by TEN TEC INSTRUCTION MANUAL America s Best SSB CW AM RECEIVER Microprocessor controlled 15 Memories dual conversion tunes 100 kHz to 30 MHz No 1254 COMPLETE KIT WITH CASE HARDWARE 74477...

Страница 2: ...KIT Manual No 74477 Circuit board and manual Copyright 2012 All Rights Reserved 865 453 7172 Fax 865 428 4483...

Страница 3: ...ixer 2nd LO Clarifier control Phase 6 0 RF Input 1st Mixer 1st LO amplifier Phase 7 0 Final Assembly and Alignment Section III Reference Information Detailed Table of Contents Specifications T KIT Mod...

Страница 4: ...stration Fig 5 1 balun transformer details Fig 5 2 Installation of Q4 C63 Q7 Phase 6 0 schematic details Fig 6 1 RF Input Bandpass Filter Assembly Fig 6 2 First Mixer Assembly Fig 6 2b Alignment Previ...

Страница 5: ...onvenient default or empty memory 15 MHz WWV z Synthesized 45 75 MHz local oscillator z 45 MHz first IF z 455 kHz second IF z 4 kHz filter bandwidth combines good AM audio response with excellent SSB...

Страница 6: ...me money could have gotten you a comparable receiver maybe pre owned very nice and ready to use But you still chose to build this kit The main reason to build equipment such as the Model 1254 is usual...

Страница 7: ...mponents Those nice double sided boards with the plated through holes should be a further motivation for close attention to directions and parts identification while soldering is fairly easy the desol...

Страница 8: ...hase 6 If you believe any parts are missing from your kit package the warranty explains how to contact us for replacement parts 7 We encourage you just to take your time with this project Build it for...

Страница 9: ...1 1 1 1 1 1 Description and Value Resistor 33 ohm orange orange black 1 4watt Resistor 1K brown black red 1 8 watt 1 VLOLFRQ GLRGH UHHQ LVSOD 0LQL SXVKEXWWRQ VZLWFKHV PRPHQWDU 6ZLWFK EXWWRQ NH FDS SR...

Страница 10: ...150K brown green HOORZ 220K red red HOORZ 1 megohm brown black JUHHQ 10 megohm brown black EOXH Schematic JMP1 3 R66 R1 R45 R28 34 40 R20 R21 R16 R17 R47 61 85 87 R15 R44 R49 R48 R2 Part No 30353 3011...

Страница 11: ...KLWH ZLUHV IHZHU WXUQV PROGHG LQGXFWRr red violet silver JROG PROGHG LQGXFWRU RUDQJH white silver gold PROGHG LQGXFWRU HOORZ violet silver gold PROGHG LQGXFWRU JUHHQ blue silver JROG PROGHG LQGXFWRU E...

Страница 12: ...WRRWK 4 KH QXW Part No 60003 51002 54002 z Transistors and Diodes Quantity 15 3 6 1 1 8 2 3 2 1 Description and Value 1 131 WUDQVLVWRU 1 313 WUDQVLVWRU J310 7 WUDQVLVWRU BF988 dual JDWH 026 7 WUDQVLVW...

Страница 13: ...Insulator pad HC 45U Schematic U2 R73 R82 R70 Y1 Y3 Y2 FL1 FL2 J2 J5 J4 J6 J3 J1 P1 P2 for YI Y3 Part No 78138 27021 30267 30856 48079 48235 48228 48339 48284 35065 35066 35238 35266 35276 38229 9174...

Страница 14: ...screw 4 self WKUHDGLQJ VFUHZ WR VHFXUH IURQW SDQHO 4 40 Setscrew for Tuning knob 6 127 2 RQWURO NQRE 3 ZLUH SOXJ DVVHPEO KHDGSKRQH MDFN 2 ZLUH SOXJ DVVHPEO VSHDNHU 7XQLQJ NQRE TEN 7 ORJR 7LQWHG VFUHH...

Страница 15: ...iron diagonal cutters or wire nippers needle nose pliers utility household pliers adjustable wire stripping tool insulated alignment tools may be home made from plastic stirrer etc medium phillips an...

Страница 16: ...Just be careful about that third multiplier band For example your kit uses 4 7 47 470 4 7K and 47K resistors each for very different purposes Table 1 B MOLDED INDUCTORS also called CH0KES These parts...

Страница 17: ...diodes installed on the Display Board The Zener and Varactor diodes must be identified exactly Here s some help TYPE Body Type Color Cathode Band 1N4148 8 Glass copper color inside Black Zener 3 Silve...

Страница 18: ...c capacitors In this kit design the mylar film parts used in the PLL filter and RF bandpass filter have values different from any of the disc capacitors with the sole exception of C11 Table 1 G ELECTR...

Страница 19: ...t some practice before working on the receiver circuit boards Building some simpler T KlT projects is of course a great way to get into kit building Another way is to take a circuit board from any dis...

Страница 20: ...may seem insulting but some folks DO carefully mount and solder all parts on the copper side of the board and wonder why the kit won t work 6 Insert all parts as close to the board surface as possibl...

Страница 21: ...0 Finishing this section results in a non tuneable receiver with full sensitivity capable of receiving a 45 MHz test signal with the Clarifier control operational Mixing the 45 MHz 1st output with the...

Страница 22: ...rs 455 kHz IF Amplifier AGC circuit Sectional Schematic and Circuit Board Pictorial Quick Reference Parts List Step by Step Assembly Progress Tests Audio p 41 IF amplifier p 45 46 Phase 5 0 2nd Mixer...

Страница 23: ...itself and it is a good orientation project Installing Parts on the Circuit Boards When we say INSTALL a part this is what we mean Choose correct part value Insert in correct PC Board location Insert...

Страница 24: ...bility of your Model 1254 Receiver 9 All parts used for the Display Board are packed together with the board itself Except for the common 1N4148 diode all parts in the Display Board kit are unique to...

Страница 25: ...1254 Assembly 4...

Страница 26: ...ohm 1 4 watt 33 ohm 1 4 watt 33 ohm 1 4 watt 33 ohm 1 4 watt 1K 1 4 watt momentary SPDT Toggle 8 pin socket 8 pin socket Freq Memory TUNE pushbutton switch multiplexing diode AM mode indicator SSB mod...

Страница 27: ...quarely seated on the board Solder ONE pin in each row Before further soldering CHECK carefully to make sure the display is squarely against the board If necessary reheat and adjust the two connection...

Страница 28: ...their panel positions as far as they can go Solder ONE side of each LED and check front panel for a good fit Resolder any LED which needs adjusting and then solder all remaining wires Before trimming...

Страница 29: ...istors 1 12 Resistor R1 33 ohm orange orange black 1 13 Resistor R2 also 33 ohm 1 14 Resistor R3 also 33 ohm 1 15 Resistor R4 also 33 ohm 1 16 Resistor R5 also 33 ohm 1 17 Resistor R6 also 33 ohm 1 18...

Страница 30: ...ldered on the front side Insert the red wire and the white A and gray B wires EXACTLY how Figure 1 3 depicts the front of the encoder and design of the plug 1 33 Mount the rotary encoder to the displa...

Страница 31: ...m lug is identified per mounting done in step 1 34 1 39 Slide the insulating sleeves over the completed switch connections 1 40 Double check all your work and set the display board aside until it is n...

Страница 32: ...n NOT the fastest possible stuffing of the board That s why a numbered instruction is provided for each part and why we follow a specific pattern for listing instruction sequences for similar groups o...

Страница 33: ...hecking correctness of parts values with brief notes on the function of each part These summaries are adapted from the complete Component Reference Index in the Reference Section of this manual Main B...

Страница 34: ...Phase 2 0 Assembly begins on page 14 1254 Assembly 13 This space is for your notes...

Страница 35: ...1254 Assembly 14 Phase 2 0 Schematic Diagram Details...

Страница 36: ...me of its supporting parts are included in this phase because its 3 580 MHz reference oscillator also supplies the microprocessor clock signal 1254 Assembly 15 Phase 2 0 Display Driver Microprocessor...

Страница 37: ...tal Reset coupling cap Vdd supply bypass for 3 Couples PLL to VCO circuits Supply bypass for U2 Supply bypass on U4 Bypass on output of U10 Bypass on input of U10 Main DC input bypass Supply summing d...

Страница 38: ...R12 also 10K 2 7 Resistor R13 also 10K 2 8 Resistor R14 also 10K 2 9 Resistor R5 47K yellow violet orange 2 10a Resistor R6 also 47K 2 10b Resistor R2 10 megohm brown black blue 2 11 Install HOHFWURO...

Страница 39: ...the board Solder U5 directly to the board do not use a socket 2 19 Slide voltage regulator U1 type 7805CT or LM340T 5 into its position as far as you can push it Then bend it back so that its heatsin...

Страница 40: ...making sure you select the 3 579 MHz crystal and not Y3 to be used in the 1st IF section 2 36 Install transistor Q12 type 2N4124 with the flat side toward R1 as outlined on the board 2 37 Install tra...

Страница 41: ...ch lug to the plated circuit board holes 2 48 Voltage regulator U10 typeNJM7810A resembles U1 in style but the lead dimensions differ Using needle nose pliers as needed shape the wide parts of the thr...

Страница 42: ...can do These possible demonstrations are NOT mentioned in the Progress Tests it is up to YOU to return to this section of the manual after each Progress Test and determine whether you want to try out...

Страница 43: ...in the row of 3 pads nearest J5 J6 Here you will simply touch a test probe from your meter to serve as a receiving antenna lt does not matter whether the test lead is connected to your meter With thi...

Страница 44: ...e the display should advance to 15 002 5 15 005 0 15 007 5 and so forth in 2 5 kHz steps lf the displayed frequency went DOWN i e to 14 997 5 etc this means that the A and B wires to the encoder are r...

Страница 45: ...the MW Memory Write function to store frequencies in memory but keep in mind that the stored information will be lost when power is turned off because the memory backup battery is not yet in use DO NO...

Страница 46: ...This space is for your notes Phase 3 0 Assembly begins on page 26 1254 Assembly 25...

Страница 47: ...1254 Assembly 26 Phase 3 0 Schematic Details...

Страница 48: ...ation is thoroughly verified in Phase 7 0 Four different transistor types are used in Phase 3 0 be sure to identify them correctly and to orient them as outlined on the board Consult Figures 3 1 and 3...

Страница 49: ...PLL active filer VCO bypass cap Supply bypass for Q25 Base bypass for Q25 Supply bypass for Q25 VCO bypass filter VCO coupling cap to PLL VCO lowpass filter VCO lowpass filter VCO lowpass filter Coupl...

Страница 50: ...47K 2 2K bifilar balun VCO source resistor VCO select Active loop filter emitter VCO pull up resistor Varactor bias resistor VCO switching VCO switching Supply resistor for Q25 Base bias for Q25 Bias...

Страница 51: ...s as indicated in Figure 3 1 3 2 Identify and install VCO coil L3 per step 3 1 and Fig 3 1 Before soldering make sure the coil base is seated FIRMLY against the board A solid mechanical fit is needed...

Страница 52: ...3 15 16 reserved 38 VCO 2 Components 3 17 Adjustable coil L2 is the VCO coil with the fewer number of windings and marked with a RED paint dot The B corner has two wire leads as indicated in Figure 3...

Страница 53: ...nstall PNP transistor Q17 type 2N5087 3 34 Install PNP transistor Q18 also type 2N5087 3 35 Install NPN transistor Q15 type 2N4124 3 36 Install NPN transistor Q16 also type 2N4124 3 37 Install transis...

Страница 54: ...also mylar film 3 61 Install C11 01 pF mylar film marked 103 Be sure to use a film type capacitor not ceramic disc for C11 3 62 Install electrolytic capacitor with correct polarization as outlined on...

Страница 55: ...the red wire switch plug to J2 and reconnect the wall transformer power supply to J1 3 78 Connect your meter s red lead DC volts range to the VCO test point and ground You will be observing voltages...

Страница 56: ...equencies shown in Table 3 1 to confirm that the selected display frequency results in the corresponding LO output frequency Table 3 1 Displayed Frequency vs Local Oscillator Output Display LO Output...

Страница 57: ...1254 Assembly 36 Phase 4 0 Schematic Details...

Страница 58: ...audio output and proper operation of the volume control When this phase is completed the receiver also can detect a 455 kHz signal such as from its 2nd mixer Phase 5 0 in either AM or SSB mode 1254 A...

Страница 59: ...bypass on U7 Bypass on output of T3 Supply bypass on U7 Oscillator cap on U7 Bypass on input of U8 Coupling cap into U7 Input bypass on U9 High frequency shunt on U8 Audio output coupling cap RF bypas...

Страница 60: ...AGC charging resistor AGC rectifier pull down AGC input resistor IF amp input load AM detector emitter resistor Forward bias for AM detector IF amp output load U8 IF amp output load U9 AGC input resi...

Страница 61: ...nd as outlined on the board just as you did when installing the jack for the encoder cable 4 3 READ before soldering on the BOTTOM solder side of the board insert J5 the 2 pin header just like the pow...

Страница 62: ...illustrated in Figure 4 1 Decide NOW if this jack should be wired for stereo normal or mono 1 8 plugs A mono plug will short out the jack if wired for stereo Progress Test 4A Audio Amplifier 4 15 Con...

Страница 63: ...soft background hiss are the only sounds you should hear i e there must be no squeals or putt putt motorboating sounds During further assembly handle the hoard carefully so that the Volume Control le...

Страница 64: ...1 not yet installed nearest to C40 180 pF very close to the headphone jack connector This pad is common to C40 the input coupling capacitor for U7 4 43 Turn on DC power to the 1254 board Adjust the vo...

Страница 65: ...er Its pin arrangement permits only one possible orientation While the markings may vary these transformers have 5 pins 2 shield tabs and are the only parts in the kit which will fit here 4 58 Install...

Страница 66: ...can fix problems in THIS section PROCEDURE 4 84 Reconnect speaker headphone jack cable power switch plug DC power supply and the Display Board 4 85 Turn on DC power to the 1254 board Adjust the volume...

Страница 67: ...t thanks to digital technology The VCO PLL circuitry in Phase 3 0 generates the RF tuning signal LO essential for mixing and converting signal from your antenna first to 45 MHz and then again to 455 k...

Страница 68: ...1254 Assembly 47 This space is for your notes...

Страница 69: ...Phase 5 0 Schematic Details 1254 Assembly 48...

Страница 70: ...result of successful completion of this assembly phase will be a receiver circuit capable of detecting very strong nearby 45 MHz signals in either AM or SSB CW mode The Model 1254 has a built in 45 0...

Страница 71: ...on Q5 Second LO output coupling cap Supply bypass for Q4 Output resonating cap for Q4 Second LO output filter Supply bypass for Q5 Supply bypass for Q7 Bypass cap on clarifier control Coupling cap in...

Страница 72: ...ding balun transformers noting that they have SIX pins Notice carefully which end of the plastic base has the two yellow gold primary wires coming from the ferrite core over the base to two pins These...

Страница 73: ...55 1 pF 5 27 Capacitor C52 15 pF 5 28 Capacitor C77 33 pF 5 29 Capacitor C78 33 pF 5 30a Capacitor C54 47 pF 5 30b Capacitor C56 47 pF 5 31 Capacitor C83 56 pF 5 32 Capacitor C39 75 pF 5 33 Capacitor...

Страница 74: ...ollowing directions while referring to Figure 5 2 Figure 5 2 Q4 Q7 C63 5 53 Examine Q4 type BF988 noting that the tab for the drain is longer than the other three It must be aligned as illustrated in...

Страница 75: ...est parts on the main board when mounted permanently Phase 5 0 Progress Test At this point in the project we have a complete signal path from the input of the 45 MHz IF out to the speaker We cannot tu...

Страница 76: ...l should change the pitch of the tone s you are hearing Rotating the tuning control will cause audible clicks 5 66 Press the SPEED button for FAST 100 kHz tuning steps as indicated by the LED below th...

Страница 77: ...Phase 6 0 Schematic Details 1254 Assembly 56...

Страница 78: ...Input lowpass filter AM broadcast notch Antenna input coupling cap RF bypass on AGC diode Q14 AM broadcast input filter Supply bypass for active antenna DC Antenna input lowpass filter Supply bypass...

Страница 79: ...used first as a guide to gathering parts for this phase It is provided as an extra help in double checking correctness of parts values with brief notes on the function of each part 6A Shielded RF Inp...

Страница 80: ...green band and install with correct cathode polarity 6 13 Install diode D14 also type BA479G per 6 12 Install the following molded inductors 6 14 orange white silver gold 6 15 DOVR 6 16 green blue si...

Страница 81: ...ace between the the board and the base of the trimmer 6 21 Install the shielded adjustable coil T6 similar in style but larger than the 455 kHz transformers installed in Phase 4 0 6 22 Install T9 a pr...

Страница 82: ...ncy on the entire 1254 circuit board 6 28 Install transistor Q2 JFET type J310 being sure to orient the flat side as outlined 6 30 After carefully double checking the parts just installed for correct...

Страница 83: ...s red red brown 6 35 Resistor R71 also 220 ohms 6 36 Resistor R68 470 ohms yellow violet brown 6 37 Resistor R69 also 470 ohms 6 38 Resistor R90 also 470 ohms 6 39 Resistor R33 10K brown black orange...

Страница 84: ...receiver circuit and may be omitted 6 58 Install transistor Q27 JFET type J310 Please Read First 6 59 The RCA type antenna jack J3 will be subjected to considerable stress over the life of the receiv...

Страница 85: ...eturn to step 7 1b to continue Final Assembly 7 1a Plug the Display Board into the Main Board and secure both the Volume and Clarifier controls to the Display Board with the flat washers and mounting...

Страница 86: ...ring the lens to the panel with very small drops of contact cement at the edges Wipe the inside of the lens clean of any fingerprints 7 6a Glue the front panel headphone jack insert in place This is a...

Страница 87: ...unt rear panel ends of chassis brackets 4 4 4 VFUHZ phillips black 60032 Mount top and bottom shells to chassis brackets in final assembly 8 4 XQGHUFXW FRXQWHU VLQN VFrew 60080 Mount front panel to ch...

Страница 88: ...gs on the panel 7 13 The large Tuning knob can be mounted to the encoder shaft in any way convenient to you Allow enough clearance so the back of the knob does not scrape against the panel Figure 7 2...

Страница 89: ...ility you can do exactly what we do in factory built equipment Use a hot melt glue gun to flow glue liberally around the outside of each VCO coil it s OK if glue also covers some of the nearby parts T...

Страница 90: ...11 T7 7 32 In AM Mode tune in the strongest WWV signal for the time of day and your location most typically at 5 10 15 or 20 MHz Make sure the display indicates the WWV exactly such as 15 000 0 MHz Fo...

Страница 91: ...e tightness 7 40 With considerable pride attach the TEN TEC logo to the front panel in the corner above the microphone jack Use a bit of contact cement on the back of the logos and between the two mou...

Страница 92: ...nto the side chassis panels for excellent mechanical durability This completes construction of the T KIT Model 1254 SWL Receiver We thank you very much for your trust in T KIT products by TEN TEC 1254...

Страница 93: ...1254 Assembly 72 This space is for your notes...

Страница 94: ...Test Circuit Description Block Diagram Practical Information for Receiver Use Connecting Antennas Active Antenna Notes DC Power Supply Considerations Mobile SWLing External Audio Connections Receivin...

Страница 95: ...455 kHz second I F Sensitivity 0 PRGH 9 IRU G 615 DW PRGXODWLRQ 66 PRGH 9 IRU G 615 Selectivity 4 kHz 6 dB Frequency Memory Display 6 digit green LED with mode indicators Power supply 12 15 VDC 250 mA...

Страница 96: ...quencies in Memory for detailed instructions The V M switch toggles between Frequency Tuning VFO and Memory Tuning See Tuning Mode Indicator below When V M is in Memory Tune mode the Tuning Control is...

Страница 97: ...d return the receiver to normal tuning mode 4 Recalling and Tuning Memory Frequencies To scroll through or listen to the frequencies in memory Press V M to enter Memory Tune mode as indicated by the T...

Страница 98: ...red signal with the Clarifier Similarly if you are tuning lower turn Main Tuning one step lower 7 Microprocessor RESET A power on reset is a quick way to clear all the memories This procedure can also...

Страница 99: ...erated within the receiver This mixing process results in a frequency conversion to an Intermediate Frequency IF A superhet receiver typically may be single double or triple conversion the Model 1254...

Страница 100: ...dual signals can be separated out for amplification and detection The typical receiver will use at least two mixers and two of these intermediate frequency stages to convert an incoming signal down to...

Страница 101: ...Figure 3R Model 1254 Block Diagram 1254 Reference 8...

Страница 102: ...5 000 MHz that would also create a difference of 45 MHz This is the image response that must be controlled by the input filter Good image rejection in this receiver is especially important since the i...

Страница 103: ...5 kHz It makes sense to take advantage of these parts to accomplish the narrow filtering we need for AM and sideband reception Furthermore we still need a lot of voltage gain to get weak radio signals...

Страница 104: ...ived signal in the speaker Because the signal strength between one radio signal and the next can vary over such a wide range receivers need some system to level the output volume as you tune across th...

Страница 105: ...e s 2K ROM is permanently programmed at TEN TEC with the instruction code to run the receiver s numerous features and the chip s 80 byte RAM provides room to store 15 frequencies Notice on the schemat...

Страница 106: ...lity The circuitry responsible for this task is mostly contained in the phase locked loop chip U3 This IC contains a reference crystal oscillator programmable dividers and phase detector The major sec...

Страница 107: ...voltage from the charge pump is applied to the varicaps and determines the output frequency of the oscillator This voltage control feature is what allows the phase locked loop to move and hold the os...

Страница 108: ...lights dimmers computer devices power lines and motors Directional loop antennas may be of interest for optimum reception at lower frequencies 100 kHz through 4 MHz In designing any antenna be aware...

Страница 109: ...ahoo etc and see what s new There s plenty there If you still are wondering what might make a good and safe first antenna outdoor for your new SWL hobby you won t be disappointed with the simple desig...

Страница 110: ...e 9 volt battery snap in series with a switch if you intend to use a battery If not solder a jumper wire from the pad marked 12VDC to the pad marked TO RECEIVER common to C3 2 If you wish to power the...

Страница 111: ...apter If you expect to use or try out a variety of antennas especially those intended primarily for ham transceiver use we suggest that you build up a simple antenna utility box for use with your rece...

Страница 112: ...or Figure 6R DC Power Connector Be especially careful to follow the polarity shown in Fig 6R because the receiver has no built in reverse polarity protection If you wish to fuse your power Source we r...

Страница 113: ...t finish If extra security or easy removeabillty are important in your situation various styles of equipment brackets are available at automotive parts suppliers CB dealers and RadioShack stores A var...

Страница 114: ...unications applications extension speakers etc A single jumper wire on the jack itself determines whether the front panel jack is set up for stereo or mono output Review Assembly Steps 4 14 ff if you...

Страница 115: ...g a program beyond the specified trial period A logging program is basically a customized information manager Many of them have elaborate searching and cross referencing features compatibility with da...

Страница 116: ...of your receiver to the intended conversion frequency and Below 100 kHz We did NOT design the Model 1254 to receive signals below 100 kHz The microprocessor control of the frequency synthesizer stops...

Страница 117: ...exact step with speech or sound variations Also see SSB BFO Beat Frequency Oscillator See CLARIFIER below BOARD Generally refers to PC board or printed circuit board BUFFER An electronic circuit stag...

Страница 118: ...he horizontal elements DUH FDOOHG D JURXQGSODQH HIGH In solid state logic circuitry to say a given device pin or circuit point is at a ORJLF KLJK LV WR VD WKDW LV VKRZV D VXSSO YROWDJH DW WKDW SRLQW 6...

Страница 119: ...gital display ORIENT orientation When we ask you to orient a kit part one way or the other we re just asking you to get it RIGHT per all the orientation illustrations or explanation which we provide P...

Страница 120: ...ng on cable prevents the inner wire from radiating RF or from picking up stray radiation such as AC hum SIDEBAND See SSB SIP Single In Line Pin Example U6 See DIP SSB Single Sideband A transmitted sig...

Страница 121: ...age level ZENER DIODE a diode designed to have a very specific reverse breakdown voltage This property makes the zener diode ideal for simple voltage regulators or precise voltage drop elements About...

Страница 122: ...228 23413 23261 23308 23246 23245 23245 23264 23330 23291 23340 23291 23260 23260 23308 23245 23260 23266 23375 23245 23376 23376 23248 23251 23245 23245 23251 23251 23245 23301 23302 23266 23261 2326...

Страница 123: ...23260 23245 23260 23260 Circuit Notes Second LO output filter Coupling cap into U7 Input bypass on U9 High frequency shunt on U8 Audio output coupling cap RF bypass on Q8 base AGC time constant cap R...

Страница 124: ...DC Supply bypass on U4 First LO output coupling cap Bypass cap on clarifier control Coupling cap into Q7 Collector bypass on Q19 RF bypass on VC0 tuning line Bypass on output of U10 Bypass on input o...

Страница 125: ...Front end AGC RFC RF input bandpass filter AM broadcast notch with C74 Mixer out crystal tuning network DC power RF choke RFC for antenna DC LO output transformer 455 kHz IF amplifier Second mixer wit...

Страница 126: ...plifier RESISTORS Reference R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 Description 4 7 10meg 10K 10K 47K 47K 100 100 10K 470 47K 10K 10K 10K 15K 1 5...

Страница 127: ...30267 30146 30134 30154 30140 Circuit Notes VCO switching Supply resistor for Q25 Base bias for Q25 Bias for Q26 Emitter resistor for Q26 Bias resistor for Q26 Gate Pull down for Q27 Supply resistor...

Страница 128: ...48339 48284 48079 48228 48235 35266 35065 35238 35066 35065 35066 35276 35276 Circuit Notes 45 MHz crystal filter 455 kHz filter Synthesizer clock set to 3 58 MHz Oscillator for product detector Seco...

Страница 129: ...SRLQW Lack of LD voltage indicates PLL or VCO problem Perform the voltage checks including VCO alignment per page 37 Explore any circuit section showing drastically different voltage readings Review...

Страница 130: ...anel jack is wired for mono Change the jack wiring to stereo per page 21 Signals seem very weak compared to other receivers 1 Make sure coils T6 T9 L10 L11 and T7 have been peaked for maximum signal s...

Страница 131: ...e will generate noise pins 1 and 2 3 0 3 0 9 0 T3 measure at anode of D12 0 6 D7 cathode 3 8 D14 anode with NO signal D14 anode maximum voltage with strong signal 1 0 4 3 Junction of R57 and C62 2 9 Q...

Страница 132: ...ourselves It is good practice to make written notes about any changes or additions you make to the original design even simple ones such as auxiliary DC audio or antenna connections We recommend that...

Страница 133: ...lder side traces is exactly as you would view the board itself with no need to look through the board from top to bottom If you wonder whether certain points should be joined by solder compare what yo...

Страница 134: ...ve harm Avoid breathing solder fumes which may cause pulmonary irritation or damage After handling any solder wash hands with soap and water before eating 4 TEN TEC Inc warrants this device to functio...

Страница 135: ...e explaining the problem and provide authorization to make repairs at prevailing ship rates 9 TEN TEC Inc reserves the right to revise this limited warranty to change or discontinue any kit product or...

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