Tuning TOKO bandpass filters in Easy BITX

I was wondering which steady signal to use of tuning TOKO bandpass filters in Easy BITX. In my earlier stint on homebrewing about 4 decades back, I used to use signals from broadcast stations to help me tune the IF transformers in the L-board assembled radio which was very popular in those days. The Easy BITX VFO covers only the amateur band, but it went up to 7300 kHz on 40m to cover the larger band plan of some other countries like the United States of America. Our 40m band is only up to 7200 kHz. It was then that VU3IZD told me that there is a broadcast station on 7225 kHz, audible at night, useful for tuning TOKO band pass filters. That was a very useful information. I listened to that station at night and peaked up the audio by turning the inner core of 40m band pass filters.