Midland 91-1060-91-1110, Service Manual Addendum, Page: 12 / 62

Alignment Procedures
Low Current Base Tech 3.5
EXCITER (TX MAIN UNIT)
1) FVR201 Sub-Audible Modulation Balance
This potentiometer sets modulation balance below 300 Hz. Carefully align this potentiometer to obtain
flat deviation from the lowest to the highest frequency programmed in the transmitter.
2) FVR202 Sub-Audible Modulation Deviation
This potentiometer determines low frequency (below 300Hz) deviation. When POCSAG and DCS are
used, it may be necessary to readjust to have enough deviation and fidelity at lower frequencies.
FVR201 and FVR202 are used together to adjust amplitude and fidelity of square wave output of the
transmitter in Analog Mode.
3) FVR203 Carrier Frequency Trim
This potentiometer adjusts carrier frequency. Its range will allow for +/- 200 Hz adjustment from the
desired (programmed) frequency.
4) FVR204 Exciter Output Power
This potentiometer adjusts the exciter’s output power level. This is nominally 80 mW.
5) L303 VCO Alignment
The VCO has already been aligned at the factory. However, if you need to re-adjust VCO after a repair,
set the VCO voltage to 10.5 V at TP301 at the highest end of the sub band using L303.. This part can be
found beneath the cover. See Figure 2. Note that tuning slug may be glued and breakage could
occur.
FVR201
Sub-Audible
Balance
VCO L303
(under cover)
TP301)
FVR204
Output Power
FVR203
Frequency Trim
FVR202
Sub-Audible
Deviation
Figure 2: Exciter Module (TX Main Unit) Alignment Adjustments
© 2012 Midland Radio Corporation
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