Another new one for me. Hows the saying go, they always come in 3’s. Well this one must be the 3rd, though i hope to prove the saying wrong and work more 🙂
Got a new antenna up. Trapped vertical for 20, 15 and 10m. Seems to be getting out better than the station master did by some and some more.
Just a quick install of the radials for testing before the storm arrives.
Still needs some pruning on the radials to bring it into resonance. Particularly on 10m
Never been spotted in Peru before and EU this early is not something I could manage either. I think im putting out a lot more signal than before.
Ultimately when you break things down a receiver is not all that complicated. Sure in its entirety it can range from ultra simple to overly complex, but fundamentally they all share the exact same building blocks, switches, attenuators, amplifiers, mixers, filters and oscillators.
Within each of these individual building blocks there are many different variations of circuit topology that can be used. For sometime I have been thinking of writing a series of posts looking at each of these fundamental building blocks in some detail and offer some typical circuit typologies that are often used in homebrew receivers.
The image above is a block diagram of the receiver that I have been building for what seems like forever. What I will probably do with each building block is take a look firstly at different typologies and then at the specific topology I used, why i used it and will more than likely add in LT Spice simulations as well just for good measure. Being able to test and compare different circuit typologies without murdering parts is certainly a good skill to have.
So I will approach things in this order, Filters, Mixers, Amplifiers, Oscillators and then a quick look at switches and attenuators.
I have built projects before with SMD components on them, but this is the first time that I have included SMD components on my own projects. Yeah i know, its nothing extraordinary, its a 5V regulator, but we all gotta start somewhere. Which got me to thinking, perhaps I should do more with larger SMD components and be able to fit more on a board. We will see LOL 🙂
Oh and for anyone who is interested, this is a respin of my band pass filter board using these variable inductors i got. Anyway, all i have done at the moment is build one filter for testing. Testing which still needs to be done, but I will get to that soon enough and post up some results.
Slowly integrating all these bits together in software and currently all the relays are clicking in sequence when I change bands on the control board. If you look closely on the upper right, you will see an updated version of the Band Pass Filter board that uses different inductors and filter topology. I need to populate and test one filter to ensure its right and then build the entire board.
Something that I did not notice was that when I changed Ecad software my mounting hole pattern has changed slightly, so neither of the old filter board designs will stack with the other boards. So i have to redo the low pass filter board and I am going to redo the rf frond end board as well and move things around to make it a little more usable and to make sure the 3.3v regulator has a heatsink on it. With bugger all current running though it, it still gets burn your finger hot and that is not right. I am starting to wonder if these ebay parts are actually dodgy or something.