AmateurRadio.com

G1KQH has found some very low cost TDA2003 ICs.  I use one of these in my VLF beacon shown in my RSGB RadCom article and on my website. Best range is just short of 6km by “utilities assisted” earth-mode.  When fitter again (currently I am not allowed to drive and I am still too clumsy when on my feet and moving because of my brain bleed last year) I intend to continue my VLF experiments. I have used these ICs at 8.97kHz, twice, and sub-multiples of that frequency.  Beyond 20kHz would be outside their spec limits, but they may still work?

G3XBM 5W VLFearth-mode CW/QRSS beacon

Evening Roger,

Used in your LF PA 10p each nuts!

http://www.banggood.com/100pcs-TDA2003-10W-IC-Car-Radio-Audio-Amplifier-Integrated-Circuit-p-944202.html

Or you can buy in 10s @ 16p each inc delivery!

http://www.banggood.com/10pcs-TDA2003-10W-IC-Car-Radio-Audio-Amplifier-Integrated-Circuit-p-922620.html

Banggood sounds Chinese. I have no idea if these are genuine parts or not. They are advertised as 10W car radio audio parts.