Elecraft KAF2 User Manual
K a f 2
Elecraft • www.elecraft.com • 831-662-8345
E
L E C R A F T
K A F 2
A U D I O F I L T E R a n d R E A L - T I M E C L O C K
Assembly and Operating Instructions
Revision A, August 30, 2001. Copyright © 2001, Elecraft; All Rights Reserved
Introduction
The KAF2 option supplements the K2's crystal filters with effective, low-noise audio filtering. It also adds
a real-time clock, allowing you to check the time or date with a tap of the K2's
D I S P L A Y
button.
Audio Filter
The KAF2 includes a passive, balanced low-pass filter (LPF) that is in-circuit at all times. It provides
significant attenuation of signals above 3 kHz, including hiss, high-pitched splatter, and carrier leak-
through. The LPF is particularly useful on quiet bands, when using headphones, or with small antennas.
Also included is a narrow, active band-pass filter for CW or data use. The center frequency of the filter is
tunable via two potentiometers. The
A F I L
switch on 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 W1.
Real-Time Clock
The real-time clock displays 24-hour time, as well as date. You'll find the clock convenient for field
operation since it eliminates the need to bring a separate clock. Time can be easily set using the
B A N D +
and
B A N D -
switches. The on-board lithium backup battery will power the clock for up to several years.
Specifications
Low-pass filter
Flatness: better than 1 dB, 0.5 to 2 kHz; Atten.: approx. -20 dB at 4 kHz
Band-pass filter
Bandwidth: approx. 80 Hz @ -3 dB, 270 Hz @ -20 dB (two stages cascaded)
Clock Accuracy
+/- 20 ppm (+/- 1.7 seconds per day) at 25 degrees C
Date Formats
MM-DD-YY or DD-MM-YY; handles all calendar months and leap years
Current Drain
Approx. 10 mA
Size
1.5" (L) x 1.5" (D) x 0.5" (H) (3.8 x 3.8 x 12 cm)
i
Caution: Some parts in this kit can be damaged by static discharge. Before handling any
transistors or ICs, put on an anti-static wrist strap, or touch a grounded, unpainted metal surface.