Vectronics VEC-820K User Manual

IMPORTANT WARRANTY INFORMATION! PLEASE READ

Return Policy on kits When Not Purchased Directly From Vectronics: Before continuing any further with your VEC kit check with your Dealer about their return policy. If your Dealer allows returns, your kit must be returned

Return Policy on kits VVhen Purchased Directly From Vectronics: Your VEC kit may be returned to the factory once you begin installing and sold ering parts, you es sentia lly take over the role of th e device's manufacturer. From this p oint on, neith er Vect ronics nor its d ealers can reas onab ly be h eld

accountable for the quality or the outcome of your work. Because of this, Vectronics cannot accept return of any kit-in-progress or completed work as a warranty item for any reason whatsoever. If you are a new or inexperienced kit builder, we urge you to read the manual carefully and determine whether or not you're ready to take on the job. If you wish to change

your mind and return your kit, you may--but you must do it within ten (10) working days of the time it a rrives .

in its pre-assembled condition only.

before you

begin construction.

The reason for this st ipulation i s,

before you

begin construction, and

Vectronics Warrants: Your kit contains each item s

Missing Parts: If you determine, during your pre-construction inventory, that any part is missing, please contact Vectronics and we'll send the missing item to you free of charge. However, the marking on one of the other items provided with th e kit. Also, make certain an a lternative part hasn't been substituted for the item you're missing. If a specific part i s no longer available, or if Engineering has d etermined that an alternative component is more suitable, Vectronics reserves the right to make substitutions at any time. In most ca ses, these chan ges will be clea rly noted in an addendum to the manua l.

Defective Parts: Today's electronic parts ar e physically and electrica lly resilient, and defecti ve components are rare. However, if you discover an it em during your pre-c onstruction in ventory that's obviously broken or unserviceable, we'll rep lace it. Just return th e part to Vectronics at the address below accompanied with an explanation. Upon receipt, we'll test it. If it's defectiv e and appears unused, we'll ship you a new one right away at no charge.

Missing or Defective Parts After You Begin Assembly: Parts and materials lost or damaged

before you

after construction begins

supplied with VEC kits are relatively inexpensive and Vectronics can replace them for a reasonable charge. Simp ly c ontact t he factory with a complet e d esc ription. We'll p roces s you r order quickly and get you back on track.

Factory Repair After You Begin Assembly:

contact Vectronics,

are not covered und er th e t erms of this warran t y. However, most pa rts

please look ca reful ly

Kits-in progress and completed kits are spec ifically

excluded from coverage by the Vect ronics warr anty.

technicians are available t o evaluat e and r epair ma lfunctionin g kits for a minimu m ser vice f ee of $18.00 (1/2 qualify for repair service, your kit must be fully complet ed, unmodi fied, and the p rinted ci rcuit board assembled using rosin-core solder. In the event your repair will require more than an hour to fix (or $36.00, subj ect t o ch ange), our technici ans wi ll contact you in ad van ce by telephone before performin g the work. Def ectiv e units sh ould be shipp ed p repaid t o:

hour rate) plus $7.00 shipping and hand ling (p rices subj ect to chan ge). To

ecified in the parts list.

to confirm you haven't misread

However, as a s ervic e t o cust omers,

When shipping, pack your kit well and include the minimum payment plus shipping and handling charges ($25.00 tota l). No work can b e perfo rmed with out p re-p ayment. Also, p r ovide a valid UPS return address and a day time phone number where you may be reached.

VEC-820

K I

nstruction Manual CW Filte

INTRODUCTION

Thank you for purchasing the VEC-820K CW Filter kit. The VEC-820K consists of a four stage, switch selectable band pass CW filter, using selected co mponent s that will make "cleaning up" CW signals effortless and easy. With the VEC820K you bring up any hard to hear signal out of a "band pile up," for easy listening, or get rid of unwanted, annoying signals. The VEC-820K also features a headphone output that will allow the use of standard monoral headphones. Although physically small in size, the VEC-820K is high on performance and reliability. The VEC-820K is powered from a 9-volt transistor radio batterv.

Construction Area: Kit construction requires a clean, smooth, a nd well-ighted area where you can easily organize and handle small parts without losing them. An inexpensive sheet of white poster board makes an excellent construction surface. while providing protection for the underlying table or desk. Welldiffused overhead lighting is a plus, and a supplemental highintensity desk lamp will prove especially helpful for close-up work. Safety is an important consideration. Be sure to use a suitable high-temperature stand for your soldering iron. and keep the work area free of combustible clutter.

Universal Kit-building Tools: Although your particular kit may require additional items to complete, virtually all construction pr ojects require a work area outfitted with the followin

tools and supplies:

BEFORE YOU START BUILDING

Experience shows there are and

our kit will probably work on the first try! Here's wha t they are:

1. Installing the Wrong Part: It always pays to double-check each step. A 1K and a 10K resistor may look an electronic circuit! Same for capacitors--a device marked 102 (or.001 uF) may have very different operating characteristics from one marked 103 (or .01uF

2. Installing Parts Backwards: Always check the polarity of electrolytic

capacitors to make sure the positive (+) lead goes in the (+) hole on the circuit board. Transistors have a flat side or emitter tab to help you identify the correct mounting position. ICs have a notch or dot at one end indicating the correct direction of insertion. Diodes have a banded end indicating correct polarity. Always double-check--especially before applying power to the circuit!

3. Faulty Solder Connections: Inspect for cold-solder j oints and solder bridges. Cold solder joints happen when you don't fully heat the connection--or when metallic corrosion and oxide contaminate a component lead or pad. Solder bridges form when a trail of excess solder shorts pads or tracks together (see Solder Tips below).

jour common mistakes

almost

the same, but they may act very differently in

builders make. Avoid these.

4. Omitting or Misreading a Part: This is easier to do than you might think!

Always double-check to make sure you completed each step in an assembly se

uence.

Soldering Tips: professional soldering. Before you install and solder each part, inspect leads or pins for oxidation. If the metal surface is dull, sand with fine emery paper until shiny. Also, clean the oxidation and excess solder from the soldering iron tip to allow maximum heat transfer. Allow the tip of your iron to contact both the lead and pad for about one second (count "one-thousand-one") before feeding solder to the connection. Surfaces must become hot enough for solder to flow smoothly. Feed solder to the opposite side of the lead from your iro n tip--solder will wick around the lead toward the tip, wetting all exposed surfaces. Apply solder sparingly, and do not touch solder directl y to the hot iron tip to promote rapid melting.

Desoldering Tips: If you make a mistake and need to remove a part, follow these instructions carefully! First, grasp the component with a pair of hemostats or needle-nose pliers. Heat the pad beneath the lead you intend to extract, and pull

ently. The lead should come out. Repeat for the other lead.

Cleanliness

and good

heat distribution

are the two secrets of

VEC-820K Instruction Manual CW Filter Kit

orientation. Many specialized diode s and low-curre nt voltag e re gulators a lso use this type packaging. Larger plastic transistors and voltage regulators use a case backed with a prominent metal tab to dissipate heat (T-220). Here

orientation is indicated by the positioning of the cooling tab.

Integrated Circuits: Proper IC positioning is indicated by a dot or square marking located on one end of the device. A corresponding mark will be silkscreened on the PC board and printed on the kit's parts-plac ement diagram. To identify specific IC pin numbers for testing purposes, see the diagram below. Pin numbers always start at the keyed end of the case and progress counterclockwise around the device, as shown:

VEC-820K Instruction I Manual CW Filter Kit

Your kit should contain all of the parts listed below. Please go through the parts bag to identif

building, If any parts are missing or damaged, refer to the warranty section of this manual for replacement instructions. If you can't positively identify unfamiliar item in the bag on the basis of the info rmation give n, set i t aside until all other items are checked off. You may then be able to identify it by process of elimination, Finally, your kit will go together more smoothly if parts are organized by type and arranged by value ahead of time, Use this inventory as an opportunity to sort and arrange parts so you can identify and find them quickly.

Qty Part Description Designation

6 24.3K* ohm resistor (red-yellow-orange-brown) R9,R10,R12 1,R12.

-4 681 K* resistor (blue-gray-brown-orange) R5, R6. R7, R8 4 1.82M* ohm resistor (brown-gray-red-yellow) RI, R2. R3, R-4

8 1000 pF poly capacitor (1000J) C1,C2,C3,C4,C5,C6

1 01 uF disc ce ram ic capacitor (103Z) C9 2 10 uF electrolytic capacitor (10uf) CIO, c1 I 2 1-4 p in IC sock ets For U1 . U2 2 LM747 Op Amp IC U l . U2

I 4P4T Slide Switch with screws SW l

6 6" Insulated wires Circuit wiring

I 9-volt batter, snap

and inventory each item on the checklist before you start

R13,R14

C7,C8

GND. VCC

PC board VEC-820K Owner's Manual

" These parts have a 1% tolerance, The tourth co lor ba nd on these

onents will BROWN, specifying a l% tolerance.

com

y (

STEP-BY-STEP ASSEMBLY

Before assembling your kit, please take time to read and understand the VEC kit warranty pr i nted on the insi de cover of t his manual. Also, read through the assembly instructions to make sure the kit does not exceed your skill level.

you begin construction, your kit will be non-returnable.

Finally, if you haven't

already done so, please verify that all parts listed in the inventory are included.

If anything is missing or broken, refer to the warranty instructions for

replacing missing or damaged parts. Note that part designators. such as R1, C3, etc., appear on a silk-screened legend

on the component-mounting side of the printed circuit board. This corresponds with the parts placement page in the manual. All parts will be inserted on the silk-screen side of the board.

If you have last-minute questions about what you need to build your kit, please refer back to the section titled "Tools and Supplies". If you're ready to begin now. here we go! The directions use two sets of check boxes. Check one when a step is complete and use the other for double-checking your work before operation.

Once

Important Note:

Capacitors Cl-C8 are made of a polystyrene type material. Avoid overheating these components when soldering to prevent melting the capacitor bod

1. Locate capacitor C 1 (1000pF). This is a polystyrene capacitor and will be marked with a "1000P on the bod

actual value in pF).

2. Mount C l and solder both leads in place, making sure the capacitor remains seated, Remove excess leads on the bottom side of the board with dia

onal cutters.

3. Locate capacitor C2 (1000 pF). This is another polystyrene capacitor. and it will be marked with a "1000J" (actual value in pF). Carefully install C2 in the same manner as C1

and solder in place.

4. Locate capacitor C3 (1000pF). This is another polystyrene capacitor and it will also be marked "1000T' (actual value in pF). Carefully install C3 in the same manner as C2, and solder in place.

5. Locate capacitor C4 (1000pF). This is another polystyrene capacitor and will be marked "1000J" (actual value in pF). Carefully install C4 in the same manner as C3

and solder in place.

6. Locate capacitor C5 (1000pF). This is yet another polystyrene capacitor and will be marked "1000J" (actual value in pF). Carefully install C5 in the same manner as C4

and solder in place.

1'EC-820K Instruction afanual CIf Filter

)

7. Locate capacitor C6 (1000pF). This is yet another polystyrene capacitor and will be marked "1000J" (actual value in pF). Carefully install C6 in the same manner as C5

and solder in place.

8. Locate capacitor C7 (1000pF). This is yet another polystyrene capacitor and will be marked "1000J" (actual value in pF). Carefully install C7 in the same manner as C6

and solder in place.

9. Locate capacitor C8 (1000pF). This is the final polystyrene capacitor and will be marked "1000J" (actual value in pF). Carefully install C8 in the same manner as C7, and solder in place.

10. Locate capacitor C9 (.0luF). This is a disc ceramic type capacitor and will be marked "103" or "103Z" (actual value in uF). Carefully install C9. ensuring not to chip the ceramic material. Once installed, then solder in

lace.

11. Locate resistor R1. This is a 1.82M resistor (brown-gray-red-N brown

ellow

Carefully bend the leads close to the resistor body to form right-angles (see followin

diagram).

12. Insert RI into its mounting holes so the resistor body rests against the board. Solder in place and trim the leads.

13. Locate resistor R2. This is a 1.82M resistor (brown-gray-red yellowbrown). Carefully bend the leads close to the resistor body as in Step

14. Insert R2 into its mounting holes so the resistor body rests against the board. Solder in place and trim the leads.

15. Locate resistor R3. This is a 1.82M resistor (brown-gray-redyellow brown). Carefully bend the leads close to the resistor body as in

16. Insert R3 into its mounting holes so the resistor body rests against the board. Solder in place and trim the leads.

17. Loca,td r"c'sistor R4. This is a 1.82M resistor (brown-gray-red-Nellmc brotk W). "~'arefiilly bend the leads close #11.

20. Insert R> into its mounting holes so the resistor body rests against the

21 Locate resistor R6. This is a 681K resistor, (blue-gray-brown-orange brown). Carefully bend the leads close to the resistor

body.as in Step #1l.

22. Insert R6 into its mounting holes so the resistor body rests-against the

board. Solder in place and trim the leads.

broN%n). Carefully bend the leads close to the resistor body as in Step

24 Insert R7 into i ts mou nting hol es so th e resisto r body r ests aga inst the

the resistor body as in Step

25. Locate resistor R8. This is a 681K resistor (blue-gray-brown-orangebroL%n). Carefully bend the leads close to the resistor body as in Step #1 l.

26. Insert R8 into its mounting holes

board. Solder in place and trim the leads.

27. Locate resistor R9. This is a 24.3K resistor (red-yellow-orange-redbrown). Carefully bend the leads close to the resistot body as in Step #11.

28. Insert R9 into its mounting holes so the resistor body rests against the

29. Locate resistor R10. This is a 24.3K resistor (red-yellow-orange-redbrown). Carefully bend the leads close to the resistor body as in Step #11.

the resistonbody rests against the

F EC-820K Instruction Afanua

CII'Fi/ter

30. Insert RIO into its mounting holes so the re sistor bod y rests a gainst the board. Solder in

lace and trim the leads.

31. Locate resistor R11. This is 24.3K resistor (red-yellow-orange-redbrown). Carefully bend the lea d s close to the resistor bod y as in Step #I1.

32. Insert RI 1 into its mounting holes so the resistor body rests aga inst the board. Solder in

lace and trim the leads.

33. Locate resistor R12. This is 24.3K resistor (red -yellow-orange-redbro,yn). Carefully bend the lea ds close to the resistor body as in Step #11.

34. Insert R12 into its mounting holes so the resistor bod_ N re sts agai nst

the board. Solder in

lace and trim the leads.

35. Locate resistor R13. This is 24.3K resistor (red-yellow-orange-red-

brown). Carefully bend the lea ds close to the resistor bod y as in Ste p #11 .

36. Insert R13 into its mounting holes so the resistor body rests aga inst the

board. Solder in

lace and trim the leads.

37. Locate resistor R14 This is 24.3K resistor (red-yellow-orange-red-

brown). Carefully bend the lea ds close to the resistor bod y as in Ste p #11 .

38. Insert R14 into its mounting holes so the resistor body rests aga inst the

board. Solder in place and trim the leads. Save the excess trimmed pieces of resistor lead. You will need it later.

39. Locate a G" length piece of insulated wire. and cut piece 1 1/4" long off

40. Using the wire strippers, re move 1/4" of insulation fr om eac h end of the

1 1/4" wire.

41. Insert the bare ends of the 1 1/4" wire into the holes on the circuit

board located at JMP2. Please refer to the section titled "Parts Placement". Fi

ure 1 for the location of JNIP2.

42. Solder the 1 1/4" wire in place at JNIP2 and trim the excess wire.

43. Locate the

ieces of excess resistor lead you saved back in step #38.

44. Install the excess lead in the holes located at JNIP I on the circuit board. Solder in

lace and trim the excess lead.

(

45. Locate capacitor CIO (IOuF). This is an electrolytic type capacitor and will be marked "lOuF" (actual value in uF). Carefully install C9: be sure to orient the negative end of the capacitor properly. Please refer to the section titled, "Parts Placement", Figure I for correct orientation of CIO. Once installed, then solder in place and trim excess lead.

46. Take the remaing 6" lengths of insulated wire and cut them in half.

47. Using the i yire strippers. r emove a 1/-1 " piece of insul ation fro m

48. Take a 3" piece o f insulated wire and insert o ne end into the hole

silk-screened INP UT on the cir cuit board. S older in pl ace and trim the

49. Take one 3" piece of insulated wire and insert one end into the hole

silk-screened #1 on the circu it board. So lder in place and trim the ex cess

50. Take one 3" piece of insulated wire and insert one end into the hole

silk-screened #2 on the circu it board. So lder in place and trim the

51. Take one 3" piece of insulated wire and insert one end into the hole

silk-screened #3 on the circu it board. So lder in place and trim the ex cess lead.

52. Locate the batt ery snap. In sert the RED le ad into the h ole silk-

screened VCC on th e circuit board. Solder in p lace and trim the ex cess

53. Insert the BLACK lead of the battery into the hole silk-screened GND

on the circuit board. Solder in place and trim the ex cess lead.

54. Locate the 4P -1T slide switch

55. Inspect the slide switch for tarnished contacts. Remove any tarnish with very fine sandpaper so the contacts are nice and shiny. This will

Note: Please refer to the section titled, "Parts Placement" Figure 2 for Steps 56

through 66.

56. Connect one 3 " piece of insul ated wire to P oint A on S W1. Do

S W

F EC-820K I

nstruction .t fanual Cff Filte

57. Connect the o ther end of the i nsulated wir e located at t he INPUT location on the circuit board to the excess lead fro m the switch co ntact.

58. Locate capacito r C 11 (1 Ouf . This is an electrolyti c type capa citor and will be marked "IOuF" with an arrow pointing to the negative

59. Trim the positive lead of C 11 so about only 3/8" of the lead

Point A

on SW 1. Solder i n place and tri m

r K

60. Connect the positive lead of C 11 at this switch contact yet.

61. Connect the other end of the insulated %sire located at #3 on the

circuit board at from the switch contact.

62. Connect the other end of the insulated wire located at #2 on the circuit board at from the switch contact.

63. Connect the other end of the insulated wire located at #1 on the

circuit board at lead from the sN vtich con tact.

64. Cut a 1 1/4"

65. Using the wire strippers. remove a 1/4" piece of the insulation from each end of the 1 1 /4" wire.

66. Connect the t t/4" piece of wire between Solder in

67. Locate (1) 14

68. Install the IC sock et at the UI lo cation on th e circuit board. Be

careful to orien t the socket correctly ac cording to t he "Parts P lacement" section Fi

Point

Con SW l. Solder in place and t rim the excess l ead

Point D

ure 1.

on SW 1. Solder i n place and trim the excess l ead

Point F

iece of wire from on e of the remain ing 3"

lace and trim the exc ess lead fro m the switch co ntact.

in IC socket.

on SW I. Solder in p lace and tri m the excess

Point B

on SW 1. Do not solder

Points B and E

on SW l.

69. Carefully bend over the four corner pins of the socket against the

70. Locate the re maining 14 pin IC socket.

71. Install the IC socket at the U2 location on the circuit board. Be

careful to orien t the socket correctly ac cording to t he "Parts P lacement" section Figure 1.

sockets for U 1 and U2. Please refer to the "Parts Placement" section.

Figure 1 for proper orientation. Be sure not to bend any of the pins underneath the IC body, and that all pins are inserted into the socket.

At this point, your kit is finished and it's time to take a well-earned break! When you come back. be sure to give your work a close "quality control" inspection.

PC Board Ins Before applying power to your kit, give it a thorough QC (quality control)

inspection. This xyill help you find inadvertent assembly errors that might prevent the filter from working or cause damage to sensitive parts. Follow this procedure:

Compare parts locations against the parts-placement diagram. Was each part installed where it is supposed to be? Was the correct value used? Start at one side of the board and work your way across in an organized pattern.

I] Inspect the solder side of the board for cold-solder joints and solder

bridges betNycen tracks or pads. Use a magnifying glass to obtain a clear view of the track area. If you suspect a solder bridge, hold the board in front of a bright light for a better view. All joints should be smooth and shiny. indicating good solder wetting and flow. Resolder any beaded or dullappearing c onnections.

If you find a construction error and need to remove a part or two, it will be easier if you have the right tools. One very convenient item for freeing soldered-in parts is a "solder sucker". This consists of a suction bulb or a spring loaded vacuum pump that draws molten solder away from the pad and lead. Alternatively. you may use a special copper braid ca lled "solder wick" (solder suckers and solder wick are both available a t your local Radio Shack or electronics supply house). If you suspect you've damaged a compone nt during removal, better to replace it than risk reusing it!

ection:

Finally, rosin flux can absorb moisture, which may cause a problem for some electronic equipment. To remove flux, use isopropyl alcohol (or 95% grain alcohol) and an old toothbrush. Apply a generous amount of alcohol with the toothbrush and scrub gently. Once the flux has fully dissolved, blot the bottom of the board dry with an untreated tissue. Giv e it a final alcohol wash, and allow to dry thoroughly.

CAUTION: ALCOHOL IS HIGHLY FLAMMABLE AND MUST BE USED WITH

ADEQUATE VENTILATION! USE SAFETY GOGGLES, AND AVOID PROLONGED SKIN CONTACT. IT THIS OUTDOORS.

S ALSO BEST TO DO

Now that assembly and inspection is completed, you're ready to begin the testing and ali

nment phase of construction.

The best way to test the VEC-820K is with a calibrated audio signal generator and oscilloscope. However. VEC-820K does not require any alignment. If all components are installed cor rec tly and in the prope r pla ces, the cente r freq uenc y of the filter will be between 750-800 hertz. The filter has three switch selectable selectivity cutoff points, 80, 110. and 180 hertz_. The switch positions on SWl from left to right are BYPASS. 180. 110, and 80. The 80 hertz cutoff is the fourth switch position from the left and is the narrowest filter cutoff. while the 180 hertz cutoff is the second position from the left and is the N%idest filter cutoff.

Probably the best method of seeing if the VEC-820K is working, or not, is to listen to some "on the air" CW signals. Then using SW1, select the filter cutoff position that best cleans up the signa l being rece ived .

If you are trying to pick one signal out of a very tight band pile up, the n try using the 80 hertz cutoff. The 80 hertz cutoff provides the highest selectivity and will greatly help you in "pulling out" those hard to get signals.

If the CW signal you are receiving is noisy with some static , then tr v either the 110 or 180 filter cutoffs. However, in these positions the filter will let slightly more noise through. but in some ca ses this may be de sira ble. The be st way to se e which position works the best is to try it. This way you can re ally he ar wha t the filter is doing for the received signal, and which switch position works the best in different band conditions.

You may use the VEC-820K with any communications receiver or scanner with

a BFO (Beat Frequency Oscillator). You can also use the VEC-820K with a ham-radio transceiver in either LSB or CW mode. The VEC-820K requires a 9volt battery power source.

There are a few items that you will need to operate the VEC-820K. We have

rovided a list of these items below for your convience.

Communications Receiver, scanner. or Ham Radio transceiver Nyith

0 9-Volt transistor radio batten

External s

Receiver or Scanner

eaker with cli

As mentioned above . you can use the VEC-820K with a communications receiver or scanner. The receiver or scanner must be equipped with a BFO, or Beat Frequency Oscillator. The BFO will allow you to fine tune the received CW signal to the VEC-820 center frequency. The center frequency of the filter being 750-800 hertz.

The filter requires audio from the external speaker or headphones output of the receiver or scanner. This positive side of the audio signal is applied to the insulated Nyire connected to

Point

A on SW 1. Apply the negative side of the audio to the negative side of the battery snap. Please refer to the "Parts Placement" section, Figure 2 for the location of

Point A

on SW 1.

Nest, connect the POSITIVE lead of the external speaker to the NEGATIVE end of C11. Please refer to the "Parts Placement" section Figure 3 for the location of C 11. Connect the NEGATIVE lead of the external speaker to the point labeled GND on the circuit board. Again please refer to the "Parts Placement" section Figure 1 for the location of the point labeled GND on the circuit board.

Nest, turn the receiver volume all the way down, then clip the 9-volt battery to battery snap. Set SW1 to the far left position. Now turn the receiver up slightly so you can hear the received signals on the external speaker. The signal you are listening to is the "raw" or "unfiltered" signal. Using the tuning knob on the radio find a CW signal. A good place to find CW signals is in the Amateur Radio bands. Once you find a CW signal switch SW I to the 110 filter cutoff. The 110 position is the third from the left. When you switch to the 110 cutoff, you will notice that the signal sounds cleaner than before. You can now fine tune the radio tuning knob for the best received signal. If using a

I E('-830/: Instruction _Manual Cll' Filter

communications receiver or scanner with a BFO control. use this control to fine tune the recei ved CW signal. If the recei ver or scann er you are usin g does not have a BFO control, it will be very difficult trying to tune the signal in properly.

If the signal you are trying to receive is i n a "pile u p", then tr y the 80 hertz filter cutoff. Then fine tune the receiver to "

Operation with an Amateur Radio tr ansceive r is basicall y the same, b ut you would use either LSB (Lower Side Band) or CW mode. All other connections arc the same.

ull out" the desired signal.

IN CASE OF DIFFICULTY

No Signal Filtering: A neNyly constricted filter that fails to work upon initial power up. generally requires

a ver< close and care ful inspecti on of all wor k. Please go back through all steps of assembly and insp ection. re ferring to the "P arts Place ment" Figure s

1. 2. and 3. Most of the time there will be a part that is not installed or not installed properly. a wrong valu e part in p lace of another. o r a broken part. A close inspection at this point will reveal some accidental mistake.

Intermittent Filter O A filter that operates intermittently may have poor solder connections. a

problem Nyith broken wires, or low voltage power source. Self-oscillation. may be caused b_v a defective U1 or U2. Also check for dirty or intermittent switch operation.

Filter Sto A working filter that fails "in-service" generally indicates a failure of in one or

both U l or U2. If you suspect a bad U 1 or U2. then with your fingers. If the part is bad, it could be HOT and could cause a serious burn. Other things that should be checked is the supply voltage of the 9-volt

No Speaker Audio:

No speaker audio can be a symptom of a bad SW 1, a broken Nvire or a bad C

11. Check the voltage from the 9-volt battery. A broken Nvire at the audio in

If technical assistance or factory repair is desired, please refer to the warranty

s Filtering:

ut to the filter can also attribute to no speaker audio.

eration

do not touch

the part

50-800

THEORY OF OPERATION AND SPECIFICATIONS

Circuit Description: The VEC-820K uses two UA747 operational amplifier integrated circuits to

form four low Q cascaded stages NNith no insertion loss. This results in a ven narrow band« idth and extremely high skirt rejection with minimum audible ringing. making good signal copying possible. The center frequency is betNNeen 7

ecifications:

hertz. The filter is abl e to drive an 8 ohm speaker or

Bandwidth:.. .................................80 Hz

Skirt Re_jcolon:..................... ......... At least 60dB do%Nn 1 octave from

110 Hz, 180 Hz (sNNitch

ENCLOSURE

Vectronics has designed a matching enclosure just for your

CIF Audio Filler Kit.

includes knobs. hard\\are. decals. and rubber feet. The

The matching encl osure is an all

VEC-820K metal box which Vectronics model

Super

Vectronics VEC-820K User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual