ELECRAFT K 2 Betriebsanleitung PDF herunterladen (Seite 21)

Circuit Details, KAT2 L-C Board

The L-C board provides eight series inductors and eight parallel capacitors, configured as an L-network. The

capacitance can be placed at the transmitter or antenna end of the network via a relay on the Control board (see next

page). Each inductor and capacitor has its own DPDT relay, with the individual sections of each relay placed in parallel

for reliability. The relays are selected under control of the ATU's microcontroller. Latching relays are used so that they

will not consume any power except when the operator is actually tuning. The relays are switched one at a time to keep

switching current low and to provide acoustically and electrically quiet operation. This results in somewhat longer tune

times.

For additional reliability, the connectors used between the L-C and control boards have gold-plated contacts, and

redundant pins are used for RF signals. Bypass capacitors are used on relay control lines to prevent RF signals from

reaching the microcontroller.

L-C Board Schematic

L8 is wound on T50-1 core (blue). All others are wound on T50-2 core (red).

= On bottom of PC board. All relays on the L-C board are on the bottom.

RELAY COMMON

W. Burdick

E. Swartz

L-NET OUT

Elecraft

L-NET IN

10.4 µH.64 µH 1.3 µH 2.6 µH 5.2 µH

Rev. Sht.

.08µH .16µH

.32µH

Date

1200

.001

.001 .001 .001

.001

C1_2

C3_4

C5_6 C7_8

C7_8

C3_4

C5_6

C1_2

K12 K15 K16

K13

K14

K10

K11

K10

K11

K12

K13

K14

K15

K16

150

300

620

C20

C23

C22

C21

C24

C25

C26

C27

C31

C32

C33

C34

C35

C36

C37

C38

C42

K5 K6 K7

10 10

10 11 12 13 14 15 16 10 11 12 13 14 15 16

L1 L2

L3 L4

L5 L6

L7 L8

C3 C4

39 82

K3 K5

1111

123456789 123456789

1 of 2

KAT2 ATU L-C Board

Pins 5 and 6 of each relay are used as tie points but are not internally connected.

NOTE: K1-K18 are single-coil latching relays, shown in the RESET position.

F 11/27/00

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