
8 T800-32-0010 Fitting Instructions 419-83210-00 419-83210-00 T800-32-0010 Fitting Instructions 1
T800-32-0010 Paging Board
The T800-32-0010 PCB can be fitted to Tait T800 Series II transmitters to enable them to function as l ow-speed paging tran smitters. This pagin g board is
for transmitters that will be connected to an external frequency standard. It is
a DFSK Modulator, suitable for POCSAG or similar paging data formats. Reference frequency stability is determined by the stability of the external standard. The PCB is not designed for use with 66 to 88MHz equipment.
Newer T800 transmittters have a Micromatch connector in the audio processor compartment. This simplifies installation.
This fitting instruction describes how to fit the PCB into existing T800 transmitters. You need to be proficient in the soldering of SMD components. It
may be preferable to obtain a T800 transmitter already fitted with this board
from your Tait dealer or national sales office.
Parts Required
The T800-32-0010 kit should contain the following items:
1 x T800-32-0010 DFSK modulator board
1 x terminated coaxial cable
1 x T800-03-1000 auxiliary D-range kit
4 x M3 x 8 Taptite Pan To rx screws
1 x coaxial socket
1 x 47 ohm resistor SMD 0805
1 x terminated 8-way ribbon cable
1 x terminated 4-way ribbon cable
DATA
DATA
Lock detect
1
7
2
8
3
4
9
5
10
6
Figure 8 Pinouts for D-Range 2
Coaxial socket
(external
reference
frequency)
2004f_01
Installation
Caution:
1. Remove the TCXO module from the synthesiser compartment of the
2. Fit the miniature coaxial socket (=SK710) and 47 Ohm SMD resistor
The radio must be powered off for this modification. After modification, do not remove the co axial lead f rom the so cket unle ss the
radio is powered off.
T800 transmitter.
(=R705) to the PCB pads provided beneath the TCXO, as shown in Figure 1.

2 T800-32-0010 Fitting Instructions 419-83210-00 419-83210-00 T800-32-0010 Fitting Instructions 7
4. Using an AC-coupled oscilloscope set to 50 mV/div , observe the signal
at TP2. Adjust RV2 until the triangle wave amplitude has been minimised.
5. Apply 600 Hz to the DATA line. Use a modulation analyser to observe
the frequency deviation on the output of the transmitter . Adjust RV1 to
get 4.5 kHz deviation on the modulation analyser.
6. Observe the transmitter’s VCO control line using an AC-coupled oscilloscope set to at least 20 mV/div and 0.5ms/div. Vary the input frequency down to low frequencies (for example 100 Hz) and check that
the control line still has a good square wave.
You may have to re-adjust RV2 and RV1 alternately to achieve a square wave
Note:
on the VCO control line and a 4.5 kHz deviat ion. Fi gure 7 show s a typical 100
Hz VCO control line waveform with RV1 and RV2 set correctly.
Figure 1 Location Of Socket And SMD Resistor
Keep the angle of the coaxial socket steep to ensure that there is space for the
Note:
Micromatch cable as well as for the coaxial cable.
3. Remove the two screws and cover plate from the second D-range
mounting hole at the rear of the T800 chassis. (If the transmitter
already has a second D-range, this must be removed so that the Drange with a second Micromatch socket can be fitted.)
4. Remove R291, R289, and R296 from the audio processor
(shown in Figure 2).
Figure 7 100 Hz VCO Control Line Waveform
S5
S6
R291
S7
R289
R296
Figure 2 T800 Transmitter Audio Processor (older version without Micromatch connector) - Top Side
If the lower cut off frequency of an AC coupled oscilloscope is too high,
Note:
excessive distortion may be introduced which will result in 'sag' on the square
wave displayed. Determine if this is a problem by directly monitoring the
original square wave source and observe any sag.
If there is sag, switch the oscilloscope to DC and use a 10µF capacitor in
series with the scope probe (observing the correct polarity) to directly monitor
the VCO control line. Note that th e trace settling ti me will be ap proximately
one minute.