User Manual

from MX800. Connect PA RF output to RS power meter and PA RF input (CNi) to
RF signal generator.
2. Set signal generator to center frequency of PA under test and reduce RF drive level
(from signal generator) to zero. Switch DC power on and check that supply is present
on L9. Assert PTT (check that no output RF power is emitted from the PA) check that
the 13.8V supply is switched through to the Hybrid on pin adjacent to RF input and
that 5V is switched to the Hybrid on the next pin along (pins not numbered on
Hybrid).
Slowly increase RF drive level from signal generator until RF power output is
approximately 25W. Adjust trim caps CT1, CT2 and CT3 for maximum power
output. Adjust RF drive level so that RF power output is 50W and fine tune the trim
caps. Check during this process that supply current does not exceed 11A and that RF
output power does not exceed 65W.
With PA transmitting at 50W into 50fl load measure DC volts FWD power sense
CN4-8 and REFL power sense CN4-5. These voltages should be approx 2.8V and
<450mV respectively. Reduce RF drive until PA output is 10W and disconnect PA
RF output cable. Measure DC voltage on CN4-8 and CN4-5 again. These should now
both read approximately 1VDC. Remove PTT.
5.2.4. VCO Board
Test Equipment:
§ Tested MX800 with Exciter VCO removed
§ PC with MXTOOLS software
§ RF Communications test set
§ Multimeter
§ Oscilloscope
§ +13.8VDC power supply
Preliminaries:
¯ Program upper, middle and lower frequencies of band (refer section 5.4 for band
split details) into 3 channels in MXTOOLS channel screen. (Note that 'Continuous
Update Enabled' on the MXTOOLS channel screen should be ticked for these
tests)
¯ Remove top cover from Exciter module and fit VCO under test. As the TX and
RX VCOs are identical the RX VCO may also be tested in an exciter. As the
receiver VCO operates at Fp, x - 90MHz the frequencies
¯ Connect Exciter to working Micro Controller via 16-way ribbon cable.
¯ Disconnect Exciter RF drive output CN 1 from PA.