Tuneup
TOPA-SV-024 Test Unit
26
August 2004
© Tait Electronics Ltd
2.2
Operation
This section explains the function of the TOPA-SV-024 test unit controls.
The procedure for using the test unit is described in the section of the
TM8200 Service Manual covering test equipment.
2.2.1
TOP / TM8000 switch
This 2-way toggle switch is used to switch attenuation resistors (R4, R5, R6)
in and out of the line from the radio’s positive speaker output to the positive
receive audio/SINAD output of the test unit (before the isolating transformer).
■
When set to
TOP
, the attenuation resistors are switched out.
■
When set to
TM8000
, the attenuation resistors are switched in
(attenuation 10:1).
Important
Selecting the wrong switch position can result in incorrect
SINAD readings.
2.2.2
TOP Mod Audio / Off / Mic Audio switch
This 3-way toggle switch is used to switch between
Mod Audio
(Tait Orca
portables only),
Mic Audio
, and
Off
(no audio signal).
■
With the Tait Orca portables, this switch can be used for setting up dual
point modulation by applying modulation to different parts of the radio.
■
For normal transmit deviation tests (Tait Orca portables and TM8200),
this switch is set to
Mic Audio
.
2.2.3
Hook On / Hook Off switch
Important
When using the test unit with Tait Orca portables, the
Hook On
/
Hook Off
toggle switch
must
be set to
Hook Off
. Tait Orca portables do not have a hookswitch,
and if the switch is set to
Hook On
, the Tait Orca portable
F1 function is activated.
This 2-way toggle switch is used to simulate the microphone hookswitch
opening (“hook off”) and closing (“hook on”). This is done by switching a
12k
Ω
resistor (R3) in or out of the MIC_PTT line.
■
When set to
Hook Off
, the 12 k
Ω
resistor (R3) is switched out of the
MIC_PTT line. This simulates the microphone being removed from the
microphone clip.
■
When set to
Hook On
, a 12k
Ω
resistor (R3) is switched into the
MIC_PTT line. This simulates the microphone being placed on the
microphone clip.
