I need a bit of advice please

[Telequipment]

Hello,  Firstly I need to build a wide range VFO, I have a feeling these are a bit of a black art, to get them right. Secondly I need to build a Noise source that quite rich in noise content, and do you shield these ?

[PA0PBZ]

What is a wide range, and what is the range?
Let's say you want 0-100Mhz, the normal way to do that is to mix 2 higher frequency sources to get what you want, so for instance a 500Mhz fixed source and a 500-600 Mhz VFO. You can't just make a VFO that goes from 0 -100Mhz...

[Telequipment]

What is a wide range, and what is the range?
Let's say you want 0-100Mhz, the normal way to do that is to mix 2 higher frequency sources to get what you want, so for instance a 500Mhz fixed source and a 500-600 Mhz VFO. You can't just make a VFO that goes from 0 -100Mhz...

That would do nicely, I thought it was more complicated There are parts of our hobby I just don't understand.

[vk6zgo]

A 500-600 MHz VFO is no pushover,either!

You're not going to make a  stable free running one,you are looking at a PLL or similar for that sort of frequency.
Oh,& its output should be within a dB or so over that range!

Maybe you can crystal lock the 500MHz fixed oscillator,but you will probably have to either multiply it up from a lower frequency,or use another PLL.

You are then stuck with designing a mixer & output stage which is flat from 0--100MHz!

Complicated?----No,but incredibly difficult to actually do!

This is why test equipment manufacturers charge big bucks!