Wednesday, March 11, 2015

Double Conversion Frequency Upconverter

The 100 MHz upconverter I've built seems to work VERY well.  I don't have any complaints as it is right now.

For the sake of experimenting, and trying to learn I've decided to try to increase the distance between the LO and the Pass Band.

In the 100 MHz upconverter there's only 9 MHz between the LO and the final pass band.  I want to try to increase that distance to have as much reduction of the LO in the final pass band as possible.  (I don't think this is required to be honest, which is why I already mentioned this is for the sake of experimenting).

I enjoy working with RF Filters so I thought this would be a chance to build two of my own (and spend some more money on an already completed project LOL).

So the idea I'm going to try looks something like this block diagram below including the filter designs to reduce the LO(s) as much as possible.

This is all subject to change, but I just wanted to post the idea I'm playing around with at this point.  I will also have available a MK-3 by mini-circuits which is a frequency (doubler) Multiplier.  I may play around with that, and then rework the filters again.  But that's just something I was kicking around with.  I could (I think) use it at the 19 MHz Mixer on the 10 MHz LO and end up with 29 MHz out of that mixer (I think), which would make it even easier to build the second LO BPF since there would then be 29 MHz from the 100 MHz second LO and the final pass band.  That's just something I've been toying with in the back of my mind.  Again I don't really thing any of this is needed at this point.  My 100 MHz upconverter is working great (so far) even in the face of some very strong signals.  I just want to learn more is the bottom line.  

Parts for this modification have already been ordered.  So this is the next revision based on my 100 MHz up-converter noted previous on this blog.