TM2000 Technical Tips

TM2000 Power Supply Latching
It has recently come to our attention that in the event of a power brown-out, the TM2000 transmodulator power supply may switch off and fail to power up again when the voltage returns to normal. This is rare and requires that the voltage drops to less than 70VAC but recovers before going off completely. To restore operation it is necessary to power down (unplug or switch off) the TM2000 completely for about 5 seconds, and power it up again. We would like to assure you that the engineering team at WaveCom Electronics is aware of this possibility and is working on a solution.

In any event, evsl recommends that you use a UPS with the TM2000 to not only prevent this situation from causing a disruption to your service but to protect your headend investment in digital headend equipment that is providing dozens of signals to your subscribers. evsl has tested two low-cost UPS models, the APC BK350 and the Tripp-Lite BC PERS450. Both function satisfactorily in protecting a loaded TM2000 chassis. evsl stocks the APC BK350, selling for $169. It can also be purchased on-line at www.microwarehouse.ca.

TM2020B Transmodulator Card F-Connector
If the F-Connectors protruding through the rear of the TM2000 chassis are over-tightened, the connector can be pulled off the board causing a failure. WaveCom is working on a solution to this problem. For current models, the connectors should not be over-tightened.

RF Output Level
evsl recommends setting the Output Level of the TM2000 cards to nearly full level output (+40 to +45dBmV for the current TM2020B and +45 to +50dBmV for the soon-to-be released TM2020C). It is best to then pad down (if necessary) the combined output to achieve the levels at which the QAM signals are combined with analog signals. The rationale behind the new TM2020C model at +50 dBmV is that many analog modulators have a maximum output level of +60dBmV, and QAM signals are operated typically 7 to 10 dB lower than analog signals.