Narrative:

I relieved a controller that had cleared aircraft X off of dro airport and had rerouted that aircraft direct hct. The aircraft was not in radar when I assumed the radar position. I asked aircraft X numerous times to reset his transponder; make sure the transponder was turned on. I continually asked aircraft X his position from dro and his altitude. I updated the data block when I could. I entered a point out to sector 41 and told the RA; (radar assistant) controller; to point aircraft X out. Aircraft Y came over descending to FL270. The transmissions were hard to hear because of the radio congestion (diversity algorithms) and the aircraft's radio. I continued to try and radar aircraft X. I asked my RA controller if he did point out the data block to sector 41; he said yes. I finally got aircraft X in radar when he changed to his backup transponder about 65 miles northeast of dro at FL250-FL260. I noticed aircraft Y at FL262 and I told aircraft Y to maintain FL270. I was informed that aircraft X had an RA. I did not hear the pilot mention this on the frequency. There are frequency problems on this sector with diversity algorithms. Depending on the location of the aircraft; you do not hear any transmissions from the aircraft but you can see the receiver light up. You sometimes have to turn off some of you receivers in order to hear the aircraft. A fix to this problem would help out many situations.

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Original NASA ASRS Text

Title: ZDV controller described possible loss of separation event; noting ATC and aircraft equipment problems as possible causal factors.

Narrative: I relieved a controller that had cleared Aircraft X off of DRO Airport and had rerouted that aircraft direct HCT. The aircraft was not in RADAR when I assumed the RADAR position. I asked Aircraft X numerous times to reset his transponder; make sure the transponder was turned on. I continually asked Aircraft X his position from DRO and his altitude. I updated the data block when I could. I entered a point out to sector 41 and told the RA; (RADAR Assistant) Controller; to point Aircraft X out. Aircraft Y came over descending to FL270. The transmissions were hard to hear because of the radio congestion (diversity algorithms) and the aircraft's radio. I continued to try and RADAR Aircraft X. I asked my RA Controller if he did point out the data block to sector 41; he said yes. I finally got Aircraft X in RADAR when he changed to his backup transponder about 65 miles northeast of DRO at FL250-FL260. I noticed Aircraft Y at FL262 and I told Aircraft Y to maintain FL270. I was informed that Aircraft X had an RA. I did not hear the pilot mention this on the frequency. There are frequency problems on this sector with diversity algorithms. Depending on the location of the aircraft; you do not hear any transmissions from the aircraft but you can see the receiver light up. You sometimes have to turn off some of you receivers in order to hear the aircraft. A fix to this problem would help out many situations.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.