Tait T830 Series, Service Manual

Page: 132 / 284

31/01/96 Copyright TEL
3.5 Synthesiser Alignment
• Ensure that the EPROM (IC1) has been programmed with the required frequen-
cies using PGM800 software.
• Single Channel Select a channel on the EPROM PCB DIP switch.
Multichannel Select the middle channel via the EPROM PCB DIP switch.
• Connect a high impedance voltmeter to the junction of L1 and R1 in the VCO (this
measures the synthesiser loop voltage).
• Earth the Tx key line.
Single Channel Tune VCO trimmer VC1 for a synthesiser loop voltage of
9V.
Multichannel Tune VCO trimmer VC1 for a synthesiser loop voltage of
9V on the middle channel.
If there is no middle channel, tune VC1 so that the chan-
nels are symmetrically placed around a loop voltage of 9V.
All channels should lie within the upper and lower limits
of 15V and 5V respectively.
Do not attempt to programme channels with a greater fre-
quency separation than the specified switching range
(8MHz).
• Check that the exciter output power is:
T836 500mW +200, -100mW
T837 800mW +200, -100mW.
• Measure the exciter output frequency and adjust the TCXO (IC1) trimmer if
required.
Caution:
This trimmer is susceptible to physical damage. Do not exert a down-
ward force of more than 500g (1lb) when adjusting.