74hc4060 freq. counter problem

hello I have made a one chip 74hc4060 frequency counter and I am having problems of reading the accurate frequency. I cannot get accuracy better than 1000Hz and between some measurement times the frequency may be completely out of range.

I cave coupled the counter to a 100mW transmitter using a single loop wire (inductively coupled).

the project I made is this
http://www.qsl.net/pa2ohh/pccnt.htm
running the program in pure DOS

I have placed the counter inside the little transmitter box, maybe it receives other frequencies too and gets "confused"?

what could it be the problem from inaccurate results?

(I use a 100MHz oscilloscope embedded frequency counter for comparison, maybe this is inaccurate?)