PCS-Electronics

Your antena could be oxidised (corroded) especially if you live near the sea or any source of pollution
However it is more likely that your coaxial downled is damaged maybe rain has got in it a tiny amount of water can destroy a whole length of cable or ther is a bad connection of break in it

One of the problems with using a RF modulator for broadcasting is most of the cheap ones have no vestigal (lower) sideband filter which means your signal takes up two tv channels instead of one so If you broadcanst on Channel 25 youre putting out a signal on 24 as well

The reason there are so few ...

BTW does anyone know how TDA7000 circuits compare against portable radios for RF performance (Sensetivity/selectivity/overload) ?

A low cost 1watt AM PLL (not PC based) would be interesting
In the UK RSL (28 day) stations can use 1W on AM. At the moment most opt for FM instead but with a shotage of frequencies in some areas (London) AM could stage a comeback in the next few years !?!

Ideally an AM rig woud tune 520-1710 in ...

I think changing the value of L3 should enable you to tune out of band ?