KOB was one of my better DX catches from Minnesota. Their 50,000 watt signal was directional at night, protecting New York City’s WABC. In the process, they nulled me as well. In addition, we had a local station (KUOM) on 770AM. KUOM was a daytimer since KOB and WABC were the only U.S. stations with nighttime authorization on this frequency at the time. But since Albuquerque was further west than Minneapolis, local sunset and therefore the time of KOB’s pattern change was later than KUOM’s sign off time. I had a 15 minute “window” each day when I could hear and aircheck KOB.
To pull this off, I used a Pioneer SX-3900 receiver with horizontal longwire antenna. The antenna was oriented so as to null out WABC. I recorded this onto a Technics stereo cassette deck with Scotch Dynarange tape.