I designed and assembled a case for my Pi Pico/Si5351 VFO that makes it a lot easier and safer to move around on the bench. Good learning for my 3D printer skills. I am working on a knob design but for now using one that’s a little short. That OLED is blue/yellow and looks good. #HamRadio #AmateurRadio

I finally assembled my Soldersmoke DC Receiver last weekend but it was not working well. I spent the week debugging. I could receive CW well but not SSB. It is very garbled. I swapped around some parts and tracked the problem to mixer build!

Today, I built a drop-in ADE-1 based mixer to test... and 💥 beautiful SSB. So I have to debug my mixer. I have a little oscillation in the audio amp, but here's a video showing how good it sounds when right #HamRadio #AmateurRadio https://youtu.be/Rvzcj72Q8lc

If you’ve seen my toots about the Soldersmoke direct conversion receiver and wondered what that was about, the Soldersmoke podcast guys put out this video this week that gives a great summary. You might like it #HamRadio #AmateurRadio https://youtu.be/5pLHBWkNxmM?si=r5xWiVFbFRDQBOge

I finished the last board of the Soldersmoke direct conversion receiver today: the 40m band pass filter. Only, I didn’t have the specified type 6 toroids. I had T68-2s, though. In the end I ended up designing my own 40m band pass filter with totally different values. Took me all afternoon, but I ended up with a very solid result! Very low loss, acceptable match.

Look at those big Soviet trimmers in there. Tested them with the NanoVNA and they are very close to spec. #AmateurRadio #HamRadio

I had an idea… I saw 3D printable coil formers for antenna coils. VU2ESE used printed forms for the Daylight transceiver.

I started to think about the tiny PITA coils I made for my VHF amplifiers. So, I designed and printed a few of these little guys and am going to test these out tomorrow with the NanoVNA! These will be nanohenry ranges.

I may do one that lays down and has blocks on both ends as 2nd trial. These might seriously improve my life for small inductors.

#HamRadio #AmateurRadio

That actually worked pretty well. Self-made card edge adapter for HP ham shack power supply. Soldering down those slots a little tough but was able to get a good solder joint along about an inch of wire on each side. Fits nice and tight so it won’t come off. Need a little more clearance for the resistor soldered on the left. Otherwise good. #electronics #HamRadio #AmateurRadio

My first self-designed 3D print worked out awesome. It’s a case to mount the speaker I bought for the Soldersmoke direct conversion receiver project. Very happy with this. That’s the audio amplifier board and soldering supplies in the background. #HamRadio #AmateurRadio

Mixer and audio amp work! Don’t have the rest of the Soldersmoke direct conversion receiver done yet. But I used the digital VFO for my 2m radio homebrew project to feed the LO port on the mixer. Used my 2m FM HT to give some signal toward the exposed end of the coax. At first I heard just screeching. Then realized one side of one toroid was backward phase. Fixed that and could hear myself on the speaker! 🔊 #HamRadio #AmateurRadio

At IRTS Hamfest in Mullingar yesterday, I picked up these two (working) Yaesu 80s era linear amps for €15 ea. They do 10W with maximum 1.5W in. The 2m version is all discrete components inside while the 70cm uses a Mitsubishi RF module. The 2m will be perfect to run as the power stage for my 2m homebrew project if I get that completed. Had never seen these before and think they’re pretty cool. Seemed like a great price. #HamRadio #AmateurRadio.

This is my version of the Soldersmoke direct conversion receiver mixer and audio diplexer board. Missing an inductor that arrives tomorrow and then I can test it. Still have two boards to go. Not going to win any beauty awards with mine, but I’ll be happy if it works! This was about 4 hours of work, mostly spent laying out the board and then fiddling with trifilar windings. Learned some stuff though. #HamRadio #AmateurRadio

I built a second amplifier yesterday, with a better matching design. And got a worse result!

I eventually figured out that there is a fair bit of parasitic capacitance in my layout. I removed the 12pF capacitor in the input matching network, replaced it with a 1pF and rewound inductors to add enough inductance. It now looks close-ish to the Qucs-S simulation. No such problem on the output network. Not sure yet what the extra capacitance is on the input. #HamRadio #AmateurRadio

After a little more tuning and some really valuable help from @n8dmt (!) I have a working self-designed antenna amplifier. I learned a lot. I will make a second version that has better wideband matching and is better constructed (I hope), given what I've learned. Here's the amplifier showing FM broadcast and APRS signals before and after. #HamRadio #AmateurRadio

I tested gain through a 23dB pad I made so as not to run over the TinySA. Bandwidth I will try to test with the VFO/TinySA.

None of it is exactly what I got from Qucs-S but I expected that! #HamRadio #AmateurRadio

Well the amplifier I soldered up last weekend that didn’t work has been fixed and seems to do what it’s supposed to. The soldering job is not going to win any awards for sure. But with the amount of rework I did, and my surface mount experience level, I think this is fine. It’s hard to tell here but the whole circuit (not the board) is smaller than the first two joints on my little finger. #HamRadio #AmateurRadio

This is my 2m band #HamRadio antenna amp I designed. It's quite different from my experiments a week ago. This one is a cascode layout with two BFR193s, a nearly perfect 50 ohm match on both sides across the whole band, and just shy of 18 dB of gain. Tuned with S-Params.

In theory! Now to build it and see how close I can get.

If you are looking at learning RF circuit design, take it from me: skip LTSpice and download Qucs-S. This is a really nice piece of software. #AmateurRadio

Soldered up the audio amplifier from the Soldersmoke Direct Conversion Receiver. Built it in my old construction style but next parts will use Manhattan style, which looks even easier. Sadly could not test and just went ahead and built it in hopes that it works because I can’t find my speaker. Ordered another one and will test this week. It has a lot of junk box parts (hence those huge caps and the parallel caps, series resistors). Fun project. Hope it works 😀 #HamRadio #AmateurRadio

I designed a small signal 2m RF amplifier around the transistors that I bought. I didn't want to reuse someone else's entire circuit because I wanted to understand how it works. I maybe 10% understand it now (this is a complex topic!), but that is enough to make something that looks like it should work. Simulated in LTSpice, but I will attempt to build.

Built around the BFR193 which is a really low noise transistor and is like €0.16/ea. #HamRadio #AmateurRadio

Messing around with making inductors for a 2m band pass filter and measuring them with the NanoVNA. I made an OK-ish fixture with some RG-316, SMA connector, and alligator clips, and calibrated it with the fixture attached. Getting pretty close to the 100nH I need for these! #HamRadio #AmateurRadio

Beginnings of an (I hope) SSB direct conversion receiver for the 2M band. This is just the VFO. And I’m very much learning here.

It uses an SI5351 with two signals 90 degrees out of phase. Controlled by a Pi Pico. While the code works, I’ll need to make it more efficient to handle the other duties that I plan for the Pico. This is my first Pico project, too. I’m using the Arduino IDE. #HamRadio #AmateurRadio

Finally got my new (to me) Kenwood TK-760H ex-commercial rig on the air today! Had a chat with a guy on the local 2m repeater who confirmed good audio from the replacement mic I bought. Radio is capable of 45W but I’m running 25W into the local repeater through my copper tape/duct tape J-pole. Very happy with this setup! #HamRadio #AmateurRadio