ELECRAFT K 2 Betriebsanleitung PDF herunterladen (Seite 22)

Circuit Details, KAT2 Control Board

T1, D1, D2 (etc.) form a directional coupler for SWR and power measurements. This type of bridge is much more

accurate than the K2's standard RF detector (D9) in the presence of non-50-ohm loads. The bridge output is buffered by

op-amp U4 and routed to the K2 control board, overriding the signal from D9. The bridge outputs are also connected to

A-to-D inputs on the microcontroller, U1. U1 measures these voltages and converts them to SWR or power readings,

using averaging and linearization techniques to improve accuracy. The EEPROM (U2) stores network and SWR data

for each band and antenna. K17 selects either a capacitor-in or capacitor-out network configuration, while K18 controls

the antenna switch. U1 "sleeps" at all times except during actually antenna tune-up, so it generates no receiver noise.

Control Board Schematic

= On bottom of PC board.

C TX/ANT Select

W. Burdick

CAP COMMON

E. Swartz

Antenna 1

Antenna 2

L-NET OUT

Elecraft

L-NET IN

GND POST

LM78L06

25LC320

5-30pF

4.0MHz

RELAY

COMMON

Rev. Sht.

1N5711

16C77

/HOLD

Date

REFL

.001

3.3K

MCLR

OSC1

OSC2

REFL

.001

C55

C54

C50

C51

100

.001

C52

C53

200

K18

FWD

0.1

OUT

C58

0.1

C59

C57

.001

100K

K17

K18

GND

K17

470

RA4

RC0

RC1

RA0

RA1

RA2

RA3

RA5

RE0

RE1

RE2

VDD

VSS

RC2

RC3

RD0

RD1 RD2

RD3

RC4

RC5

RD4

RD5

RD6

RD7

VSS

VDD

RB0

RB1

RB2

RB3

RB4

RB5

RB6

RB7

RC6

RC7

FWD

/CS

/WP

VSS

SCK

VCC

SDO

SDI

C45

C46

C47

.001

C60

10 11 12 13 14 15 16

10 10

123456789 1 23456789

nc nc

2 of 2

KAT2 ATU Control Board

54321

Aux I/O

(Sheet 1)

AUXBUS

12V

U4A

LM358

U4B

NOT USED

11/27/00

1 2 ... 17 18 19 20 21 22 23 24 25 26 27 ... 30 31

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