Alpha Radio 87A, Operating Manual

Page: 21 / 54

Page 21
Alpha 87A User Manual Rev 2.0
Section
6
Installation
(Refer to Fig. 7, page 20)
6.1 Coaxial Cable Types & Connectors
Connect the transceiver RF output to the
ALPHA 87A RF INPUT with 50 ohm coaxial
cable – RG-58C/U or equivalent. A 6 ft. cable
is supplied for this purpose.
Coaxial cable from the Alpha 87A RF
OUTPUT to antenna should be RG-8A/U,
RG-213/U, or equivalent high quality type with
a PL-259 UHF-type plug on the amplifier end.
RG8X cable is not recommended.
6.2 T/R Control Cable
The 87A has a full break-in PIN diode QSK
system requiring only the normal
interconnection when used with a modern
QSK transceiver. The Alpha 87A requires a
contact closure (short circuit) on transmit from
its RELAY jack center pin to chassis. This
function is supplied by the transceiver, usually
from a dedicated relay that is open in receive
and closed in transmit. Shielded wire should
be used for the T/R control cable. The Alpha
87A end must be fitted with a common phono
(RCA-type) plug and the other end with a
connector suitable for the transceiver. See
transceiver manual for transceiver
connections. The voltage at the relay jack is
5V at 1mA; this is acceptable for most modern
transceivers.
The T/R relay contact must close before
application of RF drive. 87A protection
circuitry prevents “hot-switching” with RF drive
applied. Modern transceivers have the proper
time delay between key-up and the start of the
transmitted signal to allow the Alpha 87A to
follow the CW keying. If a T/R timing problem
is suspected, connect the CW keyer to the
RELAY jack on the 87A, and connect a cable
from KEY OUT on the 87A to the keying input
of the transmitter.
6.3 Antenna
Connect a nominal 50 ohm antenna of VSWR
<2:1 at the frequency to be used to the 87A
RF OUTPUT jack.
6.4 Ground Wire
Connect a heavy copper strap or braid from
the #10 ground stud & wing nut on the rear
panel of the 87A to the chassis of the
transceiver and other station equipment, and
to the main station RF ground.
6.5 Green Wire
Connect to A-C power consistent with tap
selected.
CAUTION: Be sure the 87A
green wire connects to A-C ground or
neutral.