FT-920 Operating Manual
85
Overview
Phone patch operation allows linking your FT-920 to
the public telephone system to provide two-way sim-
plex communications on behalf of third parties. The
FT-920 may be used with the LL-7 phone patch unit
installed in the optional SP-8 external loudspeaker,
or with phone patch units from other manufacturers.
The diagram at the bottom of the page shows inter-
connection for the SP-8/LL-7 combination; be sure
to consult the documentation provided with units of
non-Yaesu manufacture for installation instructions.
Operation
Phone patch Tx/Rx switching may be done manually
using the PTT method, or automatically using the
VOX circuitry of the transceiver. While the manual
(“PTT”) method does not require careful balancing
of the LL-7’s bridge circuit, it
does require more work
by the operator (you must manually switch the PTT
or MOX switch every time someone in the patched
conversation says “Over”). Therefore, most opera-
tors prefer to use the VOX method whenever the
telephone signal-to-noise ratio permits. If the tele-
phone line noise level is high, however, the PTT
method may still be necessary, so you should be-
come familiar with both methods.
p
Note
You may need to contact your telephone com-
pany for permission to connect an external de-
vice, such as a phone patch, to the telephone
system’s lines. Also, you should procure and
use a suitable 600
Ω
, three-way transformer if
connecting the LL-7
and a telephone handset
to the same telephone line.
Regardless of which patch Tx/Rx control method is
used, you may need to instruct the person on the
telephone to speak slowly in a clear, steady voice
level, and to say “Over” when a response is expected
from the other party. This will serve as a notice to you
(if you are using PTT control) to switch to receive
while signaling the other station to go ahead and trans-
mit, so as to avoid “doubling” with the other station.
During all phone patch operation, you should moni-
tor both sides of the conversation at all times (this
may be required by law); this will, of course, require
a telephone at the operating position.
Summary of Contents for FT-920
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