MFJ-784B Instruction Manual
Installation Error! Main Document Only.-6
CW Sidetone Filter
The
less preferred
method for passing sidetone involves programming a
special internal CW sidetone filter. The CW sidetone filter is a totally separate,
jumper programmed, constant frequency filter. This option makes the DSP
function with two separate parallel filters. One filter is the standard adjustable
CW filter and the other is the fixed frequency CW sidetone filter. This method
has the advantage of not requiring a T/R connection, but the disadvantage of
allowing unwanted signals to feed through if they happen to be within 30 Hz of
the sidetone frequency. To enable the CW sidetone filter, internal jumpers
must be set to the sidetone frequency of your radio. Refer to page 4-10 for a
description of setting the sidetone filter. The center frequency of the sidetone
filter ranges from 300 Hz to 1000 Hz in 50 Hz increments. The bandwidth of
the sidetone filter is fixed at 50 Hz.
DSP to TNC Connections
When connecting to a TNC, MFJ suggests the use of the 5-pin ports. TNCs
need a PTT connection that is only available on these ports.
The MFJ-784B plugs directly into any MFJ/TAPR2 compatible TNC. Use a 5-
pin DIN-to-5-pin DIN cable, MFJ-5100, for connection to MFJ/TAPR2
compatible TNCs or the PK-12/96/900. MFJ offers pre-wired radio cables
(models MFJ-50xx) for connection to your radio and pre-wired TNC cables
(models MFJ-51xx) for connection to other TNCs. Refer to the appendix for
more information on these radio-to-TNC cables.
Pin To Radio Function To TNC Function
1 TNC Xmit Audio TNC Xmit Audio
2 Ground Ground
3 PTT PTT
4 Receive Audio In Filtered Audio Out
5 T/R No Connection
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