R.V.R. Elettronica VJ3000, Installation, Technical And Maintenance Manual

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R.V.R. ELETTRONICA S.r.l. (BO) Pag. 80
VJ3000 - Technical and Maintenance Manual
2) Select ST.BY. (4 Fig.6).
3) Perform SETUP 7 and connect a power supply, set to 0 V, across
R6, situated on the power supply module P1 (3 Fig.7A). The
correct polarity should cause a clockwise meter needle
deflection.
4) Increase the power supply voltage and check for a proportional
increase of Grid current on the VJ3000 meter and of the power supply
current.
5) Adjust trimmer R29, situated on the protection card for the correct
display on the VJ3000 meter.
6) Increase the current through R6 to 400mA.
7) Adjust trimmer R31, situated on the protection card, to trigger the
Ig proction. This is confirmed by the lighting of the IG indicator
(led 20 Fig.5 is red).
8) Reduce the current to 250 mA.
9) Wait for the protection module to automatically re-enable the unit
and repeat step 6 to check the right threshold (400 mA).
C) SWR PROTECTION ADJUSTMENT
To adjust the SWR protection circuit, first perform SETUP 8 Output
power should be set to about 10% of maximum power i.e. about 300W.
1) Connect a mis-matched dummy load (eg. 25 Ohm 3 KW) to the amplifier
output, in series with an in-line wattmeter (Bird mod.4715).
2) Having switched on the amplifier (note that the rear panel must be
in place) already calibrated for the exciter operating frequency,
from 0W, gradually increase output power until a reflected power
of 300 W is displayed on the external wattmeter. Ensure that the R.F.
probe fitted to the directional coupler is correctly orientated.
3) Adjust trimmer R56 to obtain the same reflected power reading on the
internal meter (9 Fig.3) as displayed on the external meter.
4) Adjust trimmer R58 to trigger the protection system. This will be
confirmed by the lighting of the V.S.W.R. led (16 Fig.5).
Note: This procedure may need to be repeated several times. The protection
circuit will disable the amplifier for at least 60 seconds.
D) POWER GOOD AND DIRECT POWER PROTECTION ADJUSTMENT
The threshold of this protection can be set according to the