Frequency sintetizer for heterodyning

Hi,
I have two very wonderful IFR signal generators but also quite
expensive. They are perfect but I want to test some cheap version of my
instrument that is an advanced microscope.
I know people replaced, in applications as mine, a signal generator with a
NE555... wow... I mean... I worked with NE555 14 years ago when I was 14
y.o.
At the moment I'm working at MHz region with two equal but tuneable
frequencies with a certain phase delay between them. Supposing to move in
the KHz region I think I could use NE555.
So the questions are:
1) does exist an easy way to use to coupled NE555 with the same frequency
but with a adjustable phase delay between them?
2) is it possible to use NE555 to have two slightly different frequencies,
in the way I can control the difference?
3) is there some chip easy to use as the NE555 but that work in the MHz
region?

Ok... I thank you anyway... hoping for some suggestion or references. Is
there some website with schematics?
Bye
Alessandro

 

I thought they were for giving to students to play with

 

in that case was not for heterodyning but homodyning and was a work in which
they didn't need do be very precise.
In my case I could try to "downgrade" all the system for particolar
application.
Anyway I got that for these reasons is impossibile to make heterodyning for
the intrinsic unstability.
Not a problem I think... there are a lot of low-cost possibility