Editor’s note: This is a guest article written by fmdxing, an WTFDA member from Australia’s east coast who has a DX blog at http://fmdxing.wordpress.com/. Additionally, the editor of this website has modified his Denon TU-1500RD radio with 110 KHz filters in the ‘narrow’ tuning mode in 2006 and saw a marked improvement in reception.
By fmdxing
DXers have modified the Intermediate Frequency (IF) ceramic filters in their radios for years. Scroll down any DXing website (this one included) and it is likely there are notes about radios being modified. Why would DXers take apart their radios and replace small, seemingly unimportant components? One damaging reason is bleedthrough or adjacent channel interference.
Bleedthrough is a radio condition where a strong, local radio signal can be heard on a neighboring frequency (i.e. a local 105.9 MHz signal booming in on 106.1 MHz). Strong bleedthrough on any frequency can make it difficult to pick up other signals — something that can ultimately make DXing impossible.
Turning a stock radio (which can only satisfactorily receive local FM stations) into a DXing ‘powerhouse’ can often be achieved by simply swapping out the wide factory IF filters (i.e. 230 or 180 kHz) for narrower filters (i.e. 150, 110 or 80 kHz). The writer of this article suggests a common solution to the problem: 110 kHz filters.
This writer prefers to use conventional component FM tuners rather
FM Radio DX 