The Continuation of the Transverting Conundrum

Well,

I've been fiddling some more with my experimental 4M Transverter project.

I've built the RX converter:

This is fairly simple in that it takes the 70MHz signals from the antenna, amplifies them and then mixes them with the 60MHz local oscillator we developed last time:

http://g0mgx.blogspot.co.uk/2014/09/to-transvert-or-not-to-transvert.html

and results in a 10MHz signal at the output. I've done some initial tests on this down converter and it seems to work as expected.

The transmit side is still work in progress:

On the right you can see part of a traditional doubly balanced mixer - I've used BAT85 diodes this time for a change.

The mixer mixes the 10MHz drive signal with the 60MHz local oscillator to make the 70MHz (plus all the harmonics and also the difference). This is fed through a band pass filter, which sweeps like this:

and then amplified and passed through another filter. The second filter is also a band pass at the moment, but I expect I will swap it for an identical low pass filter I made for the RX side - the second band pass filter is no way near as good as the first for some reason.

I then need to make a linear amplifier to increase the output to about 10W to drive my linear.

Good, egh?

To Transvert or not to Transvert

Well,

Been thinking more about my antics on 2M & 4M Meteor Scatter:

http://g0mgx.blogspot.co.uk/2014/06/cq-on-them-there-meteor-trails.html

And wondering how my TS-990 would perform with transverters for 2M and 4M.

There are many designs out there for transverters, one of the best I have found are here:

www.g4ddk.com

Sam does a transverter for 2M and 4M; I have decided to join his waiting list....

In the meantime, you may recall we had a bash at some 4M kit a while ago, so I thought I would build on that experience and have a go at making a 4M transverter myself:

http://g0mgx.blogspot.co.uk/2012/06/even-more-4m-or-70mhz.html

So here is what we have so far, the "traditional" approach would be to build an oscillator for 42MHz and then mix it with 28MHz IF. Well, I don't have such a crystal so I have started with a 20MHz crystal oscillator and a frequency tripler to give me a LO of 60MHz. This mixed with a 10MHz (30M) IF will get us to 70MHz.

Here's the LO:

It's output looks like this:

and its harmonics like this:

So I need to feed this through a low pass filter, which inits simplest of forms, looks like this:

The one I have made above sweeps like this:

So this is looking like a reasonable start.

I need to make the down converter next, this will be made with some dual gate mosfets - I've ordered some BS981s which should perform well at these frequencies. Hopefully they will drop through the letterbox any day soon.

Cat's not been helping much at all today:

Good egh?