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Olson Technology OTPN-2000C User Manual

Page 7

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INTERNAL TEST POINTS and ADJUSTMENTS

The OTPN-2000C receiver has an internal plug-in pad to allow the RF output level of the
node to be adjusted. There is also a plug-in equalizer to compensate for cable slope.
These adjustments are accessed by removing the nine thumbscrews that hold the top
cover on. The unit should not be operated for extended periods with the top cover
removed. This is because of RF ingress and potential thermal problems due to
unchanneled air flow. When replacing the top cover, be sure to firmly tighten all
thumbscrews. RF ingress or oscillation can be caused by loose screws.
The locations of the internal adjustments are shown in the following diagram.

The forward adjustments are at the left. The forward test point is at the right. The reverse
pad and test point in the center are used only when an OTPT-300 is attached. The
wavelength select jumper is used to compensate the received power test point for the
changes in responsivity of the photodiode with wavelength.

The OTPN-2000C has one external test point. It should be measured with a high
impedance voltmeter. The received power test point is calibrated at 1V per mW @ 1310
nm. This test point is for long-term monitoring purposes. The optical power should be
measured with a power meter at the time of installation. The input test point is calibrated
at the factory at 1310 nm. The value at 1550 nm may be off by 15% due to photodiode
responsivity variations. The input test point reading will be considerably in error if the
input wavelength is 1550 nm and the internal jumper has not been changed.

EXTERNAL TEST POINTS

WAVELENGTH SELECT

1550nm

1310nm

-20dB

REV

T.P.

-20dB

REV

T.P.

FWD

EQ

FWD

EQ

FWD

PAD

FWD

PAD

REV PAD

-20dB

FWD

T.P.

-20dB

FWD

T.P.

FLA

T

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