Elecraft XV Transverter Owner's Manual - Manual (Page 29)

- 25 -
Control Circuits
Power Control: The DC power control circuit is configured with jumpers
to allow it to work with an Elecraft K2, K3 or any other suitable rig.
When used with a rig other than an Elecraft K2 or K3, a jumper is placed
at JP5 to bypass Q5 and D16. The transverter power is then controlled by
front panel power switch S2. Closing S2 enables relay K3, applying +12
volts to the transverter circuits.
When the transverter is used with an Elecraft K2 or K3, the control circuit
automatically turns the transverter power off whenever the K2 or K3 is
turned off. No jumper is used at JP7. As long as the K2 or K3 power is on,
+12 volts is supplied via pin 8 of the DB-9 connector to Q5, which
grounds the return side of power switch S2 through D19. When the K2 or
K3 power is turned off, Q5 will turn the transverter off automatically.
Of course, power switch S2 on the transverter must be on. If desired, a
jumper may be placed at JP8 to disable the transverter power switch. The
transverter power then is controlled only by the K2 or K3 transceiver.
Controller U1 on the front panel PCB enables the three-diode light bar
D11 through Q6 whenever the transverter is active. If the transverter is
used with an Elecraft K2 or K3, it is active whenever DC power is applied
at J2 and it is selected by the K2 or K3 as described below. If the
transverter is not used with a K2 or K3, light bar D11 is enabled whenever
DC power is applied at J2 and power switch S2 is on.
Fan Control: The XV432 has an internal cooling fan that operates
whenever +12 vdc is present at the transverter power connector.
Transmit-Receive Switching: Switching between receive mode and
transmit mode is by a ground at the KEY IN connector or, if an Elecraft
K2 or K3 is used, when the 8R signal at pin 9 of the DB-9 interface goes
to a logic low.
When used with an Elecraft K2 or K3, the transverter is enabled
automatically by the BAND switch on the K2 or K3. A K2 identifies the
transverters as TRN1, TRN2 or TRN3. A K3 identifies the transverter as
XV1, XV2 or XV3. Switch SW1 associates the transverter with the
corresponding number at the K2 or K3. SW1 selects an analog voltage
level depending upon the position of the switches. This voltage is sent as
the ID signal to controller U1. Controller U1 monitors the AuxBus signal
from the K2 or K3 and enables transmit/receive switching when the
transverter ID corresponding to the setting of SW1 is received.
When the transverter is used with rigs other than an Elecraft K2 or K3, all
the switches are off. The transverter is enabled whenever the transverter
power switch is on.
When a transmit mode command is received via the KEY IN connector or
by the 8R line from a K2 or K3, controller U1 provides a ground return to
close relay K5. Relay K5 provides +12 volts to relays K1, K2, K6 and K7
and supplies bias voltage to RF power module U7.
I.F. Port Enable: Relays K8 and K9 must be energized to connect the
external rig to the transverter circuits. These relays are energized by
controller U1 by providing a ground return on the IF EN command line.
When the transverter is used with an Elecraft K2 or K3, the controller
enables the I.F. port only when the transverter is selected by the K2 or K3
band switch as described above. This feature allows several transverters to
be “daisy-chained” together through the 28 MHz TX/RX and 28 MHz RX
connectors.
When the transverter is used with other rigs, the I.F. port is enabled
whenever power switch S2 is on. If several transverters are “daisy-
chained” together, the desired transverter selected by turning its power
switch on and leaving any other transverters off.
I.F. Overload Protection: If the transverter is not switched to transmit
mode before a high-level I.F. signal is applied to the 28 MHz TX/RX
input, mixer Z1 might be damaged. This will happen if the external rig
does not supply a ground the KEY IN connector or, if a K2 or K3 is used,
the 8R signal at the DB-9 connector does not go low to change the
transverter into transmit mode. To prevent damage to the mixer, a
protection system will automatically disconnect the external rig from the
transverter circuits and limit the signal level at the mixer I.F. port.
Diodes D6 and D12 in the overload detector circuit rectify a sample of the
transmit RF and produce a DC level that will cause the control circuits to
open relays K8 and K9. This voltage is supplied as the ODET (overload
detect) signal to controller U1 on the front panel PCB. Also, when an
overload is detected controller U1 flashes the front panel LEDs at about a
1 Hz rate to alert the operator. The transverter will remain disconnected
with the LEDs flashing until the controller is reset by turning the power
switch off, then on again.