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E
L E C R A F T
Revision D, Aug. 20, 2002. Copyright © 2002, Elecraft; All Rights Reserved
Introduction
The KNB2 noise blanker can be used to suppress most wide-band noise, including that generated by
automobile ignition systems, power lines, and appliances. In many cases, signals that were completely
"buried" in noise will become easy to copy with the blanker turned on.
Various settings are provided to make the noise blanker more versatile. Two blanking pulse widths are
available, as well as two noise threshold settings. These selections are made using the K2's front panel
and
buttons, respectively. Refer to Using The Noise Blanker for details.
L E V E L
The KNB2 plugs directly into the K2's RF board with no additional wiring. It is controlled by the main
processor on the control board via the K2's "AuxBus" network. (Complete circuit details can be found on
the back cover.)
Specifications
Blanking Widths
Current Drain
Size
i
Caution:
Some components in this kit can be damaged by static discharge. Before
handling any transistors or integrated circuits, always put on an anti-static wrist strap or touch any
grounded, unpainted metal surface.
K N B 2
Assembly and Operating Instructions
NB1, 10 µS; NB2, 70 µS
Approx. 13 mA when turned on, 2 mA off
2.3 x 1.4 inches (58 x 36 mm)
N O I S E B L A N K E R
N B
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Table of Contents
Related Manuals for ELECRAFT KNB2
Summary of Contents for ELECRAFT KNB2
- Page 1 L E V E L The KNB2 plugs directly into the K2's RF board with no additional wiring. It is controlled by the main processor on the control board via the K2's "AuxBus" network. (Complete circuit details can be found on the back cover.)
- Page 2 Parts Inventory The table below lists all parts in the kit. If you have trouble identifying any of these items, consult the K2 Owner's manual, which has photographs of similar parts. Ref. Description Qty. Capacitor, 39 pF, 5%, disc Capacitor, 100 pF, 5%, disc ("101") Capacitor, 820 pF, 5%, disc or monolithic ("821") C9, C11, C13 Capacitor, .001 µF disc or monolithic ("102")
- Page 3 Wire, #26 enamel 3 ft. MISC KNB2 PC board, Elecraft P/N E100087 Assembly The noise blanker board will be mounted directly above the K2's I.F. amplifier transistor, Q22. To avoid shorts between the bottom of the noise blanker and Q22 (or Q22's heat sink), you must trim all noise blanker component leads to 1/16"...
- Page 4 Install resistor networks RP1 and RP2. These networks are symmetrical and can be installed in either of two orientations. Note: Don’t confuse RP1 with connector P1, which also has 8 pins. Before handling U3, touch an unpainted, grounded surface. This is a CMOS IC that can be damaged by static discharge.
- Page 5 Trim and solder the leads of L1. When soldering, make sure that the solder binds well to the leads. If the lead appears to be an “island” in a small pool of solder, chances are it is not making good contact. It’s a good idea to measure from pad to pad using an ohmmeter to be sure the leads are making contact.
- Page 6 Install the 8-pin female connector on the RF board at J12 as shown by its outline near W5. Do not solder yet. The side view of J12, below, shows how it should appear once properly seated. Solder just one pin near the middle of J12, on the bottom of the RF board. Then, if the connector is not sitting completely flat against the RF board (or is not vertical), reheat this pin and carefully press the connector down.
- Page 7 U3 soldered in backwards or the noise blanker may not be plugged in correctly. Using The Noise Blanker The KNB2 works best on wide-band pulse noise, such as that created by power lines, auto ignition, and some appliances. Like other pulse-type noise blankers, it will not suppress atmospheric (random) noise or noise that occurs only at specific frequencies.
- Page 8 = On bottom of PC board. 2 N 3 9 0 6 , MC1350, 12C509A PN2222A 7 8 L 0 6 2 N 7 0 0 0 Elecraft KNB2 Noise Blanker Rev. Date Sht. W. Burdick E. Swartz 8 - 1 9 - 0 2...
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