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Sunday, April 29, 2018

IC-R8600's Digital Twin Passband Tuning

There is a handful of nearby AM radio stations that are very strong here and sometimes make it difficult to hear stations on adjacent frequencies, for example, WPRX on 1120 kHz running 1000 watts 2 miles away, WNTY on 990 kHz running 2500 watts 5 miles away and WLAT on 910 kHz running 5000 watts 8 miles away. But by far, the worst is WTIC on 1080 running 50,000 watts line-of-sight 16 miles away. Its 50 kilowatts are bad enough, but it also uses IBOC, which dumps hash on 1070 and 1090 that is 20 over 9.

Despite the hash, I have managed to bag seven stations on 1070 by rotating my radios and/or antennas to null WTIC's signal.

I wondered if my new whiz-bang ICOM IC-R8600 could handle WTIC's IBOC hash. Studying the IC-R8600 manual, I thought that the radio's "Digital Twin PBT" might solve the problem.
"The Digital Twin PBT (Passband Tuning) electronically narrows the IF passband width by over wrapping the passband frequency ranges of 2 PBT filters (PBT1 and PBT2), to reject interference."
So I saddled up to the radio last night around 2330 local time, powered up the IC-R8600 and found Radio Havana loud and clear on 530 kHz, so conditions were very good and WTIC's IBOC hash would be very strong. Tuning to 1070, all I could hear was the IBOC hash.

I selected the Twin PBT option and began adjusting the two PBT filters (see figure above). In less than a minute, the IBOC hash gave way to The Eagles singing "Already Gone" on CHOK in Sarnia, Ontario!

Twin PBT did the trick!

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