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Page 1: ...the K2 front panel selects either O F F LPF only A F 1 first CW filter stage or A F 2 both stages The operator can choose to treat both CW filter stages as a single setting A F 2 by installing jumper...
Page 2: ...istor 470 ohms 1 4 watt 5 yellow violet brown E500003 2 R13 Resistor 910 ohms 1 4 watt 5 white brown brown E500070 1 R14 Resistor 2 7 k 1 4 watt 5 red violet red E500005 1 R9 R10 Resistor 10 k 1 4 wat...
Page 3: ...with outlines of the ICs U1 U4 and most other components is the top the side with the KAF2 label is the bottom If an assembly step does not specify top or bottom the component should be installed on t...
Page 4: ...16 Trim the leads of C15 and C16 as short as possible preferably flush with the board On the top side install the 068 F capacitors 683 __C1 __C2 Install electrolytic capacitor C10 10 F The lead of C10...
Page 5: ...ded metal surface Install transistors Q1 Q2 and Q3 J309 as indicated by their outlines The installed height of the transistors should be no more than 3 8 9 mm Use a minimum of soldering time 1 2 secon...
Page 6: ...it is installed in the socket at this time remove it Install cylindrical crystal X1 vertically between U3 and BT1 The exposed lead length should be 0 1 2 5 mm or less Be careful with the crystal s le...
Page 7: ...s of the resistors right at the body then remove the leads one at a time Use long nose pliers to hold the lead then heat the joint until the lead slides out with very little pulling force If R18 and R...
Page 8: ...oard could be damaged J1 J2 MCU U6 KAF2 i If the standoff does not line up with the hole near the middle of the KAF2 module you may have the pins of J1 and J2 shifted by one position Use the original...
Page 9: ...ld see A F 1 on the display indicating that the first band pass filter section has been enabled The receiver sound should change due to the narrower bandwidth The signal may decrease in amplitude Usin...
Page 10: ...ld see a time display HH MM SS The time may not be changing at this point and may be set to 01 01 01 or to a random time Note The receiver is not muted when time is displayed so you may hear microcont...
Page 11: ...ement in skirt selectivity This can really help with DXing QRP contests and other situations where much of the activity takes place right at the noise floor When A F 2 is selected overall gain will be...
Page 12: ...notes Bypassing the Audio Filter The audio filter can be bypassed by setting S1 on the KAF2 module to the OUT position In this setting the real time clock will still work if enabled but the low pass...
Page 13: ...dule processors which generates noise that is audible at some frequencies The K2 does not mute the receiver when date or time is being displayed because the operator may want to use WWV or some other...
Page 14: ...tch signals and noise Shielded inductors and a balanced filter topology are used to prevent noise and hum pickup The passive filter contributes no noise of its own and is located after all active filt...
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Page 16: ...J1 must be removed when the KAF2 is installed 3 9K RP1 1 2 3 9K RP1 7 8 C13 C12 C14 C15 12V 82 mH 82 mH LPF1 LPF2 KAF2 Audio Filter RTC A R11 R12 220 220 910 5 6 7 U1B 10 9 8 U1C R4 R5 R6 R8 R3 R7 R1...
