Receiver Front End: Pt_2

http://robs-blog.net/2018/12/22/receiver-rf-front-end/ To see where things have come from, here is a link to the original post:

So between the first iteration and the 2nd, I have changed from using Sprint Layout to using Diptrace. I have tried a few different programs from Kicad to the free version of Altium and I just could never get the hang of how to make components and footprints in either of them

Diptrace on the other hand I find to be much more intuative and straight forward to use and I can make components and footprints in it with easy, as will be seen later when i get the latest batched of board back from china and write a blog post. So many new parts all created by me in the one library so i can find all my parts easily.

Anyway, to the board at hand. Its still got a couple of minor mistakes on it, the cap footprints were in 2.54mm not 5mm which the caps I use mostly are, the 5v regulator and caps are in the way of the right angled SMA connector and I am not sure that the variable RF preamp is actually varying. Circuit wise it should work, but the spectrum analyzer was not showing any gain change.

Anyway, the design will not be changing now, its built, tested and it works. And i can stay like that :

The gerbers can be downloaded from HERE: http://robs-blog.net/Files/rf-frontend.rar

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Radio Bebek RF PreAmp

Radio Bebek RF Preamp
Powered Up and Testing
100mV in and 500mV out

So the RF preamp has about 5x gain. On 40m its probably not really needed unless there is a lot of loss in the filters. Which in this case might actually be the case as the RF path from the antenna goes through the LPF, into the Relay and then into the BPF. So a little gain ahead of the mixer might be a good thing.

One thing that I left out for now were the back to back clipping diodes. I am only building this as a receiver pretty much to begin with and I am not sure clipping diodes are really necessary. Next I will be working on the LPF and BPF. Need to do some LTSpice here to make sure my values are correct.

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