EFHW QRP Antenna

Wanted to make some EFHW antenna for portable use.  I really should use a larger toroid, but the largest I had was an FT50-43, so thought I'd try with that.  I printed this from thingiverse, but used the smaller toroid.  Cut the wire for 20M and trimmed it while measuring with the NanoVNA.  Tried FT8 and WSPR with 5W.  Seemed to work pretty well.  The only thing I found is that scanning the SWR with the G90, sometimes I would get this thing where the SWR was super low, and then would jump up super high.  Not sure if that was something having to do with the tuner in the G90 or what.  Also, at one point I had it tuned and tried a higher power (to see if the toroid would get hot), and the SWR jumped up while transmitting.  Don't know if that is some sort of common mode current or what.

Overall though, pleased with this antenna.  The wire winds up nicely on the form, and was able to get out.  I'm not sure if it is particularly better than the DS-1 vertical, though.  Will need to make this again using a larger toroid and do some side-by-side experiments.  

Loving 20M

 Hitting all the continents with WSPR.  Loving this new dipole!

New Antenna Day

 I've been dealing with a lot of noise at my QTH.  I suspect it is power line noise, but it seems to be worst on 40m.  My little DS-1, while cute and while it works, I'm not sure how *well* it actually works.  So finally broke down and built another dipole, this time taller and for 20m.

I somehow ended up with an extendable painter's pole, and thought that would work nicely.  I 3d printed an end-cap to screw onto it, and 3d printed a little dipole middle piece to hold those parts.  Didn't use any balun or anything.  Oversized the wire a good bit and then folded it back while measuring with the NanoVNA until I had a decent SWR in the middle of the 20m band.  Am using the umbrella hole in our little iron garden table (also something we ended up with for free) to hold it up.

I don't know if it was the higher dipole or band conditions, but achieved a goal of getting to both Australia and the UK! Woohoo!

Edit: Also was heard in Japan on FT8!!!  (Didn't manage to work anyone on FT8, but was picked up a bunch of places)

Edit 2: But I did manage an FT8 QSO with XE2AFL in Mexico!  Woohoo!

New Radio Day - Xiegu G90

 After only using self-built rigs all this time, I finally broke down and bought one.

Called CQ with it last night after the kids were in bed, and managed to have a nice QSO with KE6HCE, who is actually in the same town.  :)

Today I made an audio cable for the CE-19 adapter.  Followed instructions here, though I seemed to have gotten the headphone/mike backwards.  No worries on that, just had to reverse the labels.  Managed to decode off the bat, but the StarTech audio interface I was using wouldn't put out sound.  (Probably need to install a driver, since it has multiple output options).  Switched to another USB interface I had, but couldn't get the VOX to work (following directions here).  Finally found I needed to adjust the VOX gain up to 5, then it worked.

Tried FT8 first, but wasn't getting anyone.  Also, needed to turn my power down to 2W, because it was taking more than my bench supply was able to give.  (Need to look at getting proper supply for this.)  Moved over to WSPR, and got some nice results on 20m using my QRPGuys DS1.

Baby's First PCB

 Along the lines of making an SSB, I thought using bi-directional amplifiers would simplify things (as in the BitX).  I decided to make them termination-insensitive as in W7ZOI's design.  As I would end up making several of these, and they seem pretty useful building blocks, I decided to dip my toe into PCBs for the first time.

I decided to try JLCPCB, as they have very inexpensive prices *and* I could get them manufactured there, which would allow me to make them smaller and use small SMT parts that I wouldn't normally use (as by the time in the day I can work on my projects, my eyes do not like that...)

I got some really great advice on the EEVBlog forums.  For one, I found searching through the available parts *really* hard, and someone suggested this project that scrapes JLCPCB's parts list and presents a *much* nicer search interface.  One of the main things is it is much easier to find "basic" parts, which don't cost you more to add ("extended" parts cost $5/part since someone has to manually load them).

I used EasyEDA and followed one of Electronoobs YouTube tutorials.  After some back and forth on the design based on feedback from the forums, I ended up with this:

Ordered it, and a week later I had this

Very pleased.  Hooking it up and measuring it on the oscilloscope (into a 50 ohm load), it looks like I am getting 12-13dB voltage gain at 7Mhz from around 10mV up to 272mV without distortion.  I need to go back and look at my notes - seems lower than I was expecting.  Also want to measure with the NanoVNA (for bandwidth) and the TinySA (for harmonics).  But that will probably need to wait for another day.  Here are a bunch of pictures:

Baby's First Crystal Filter

 I've decided I want to make an SSB, along the lines of the BitX or something.  Along those lines, I decided I should make a crystal filter for use in it.  I'll be following the directions from W7ZOI.

First, I ordered a lot of 100 9MHz crystals off of Aliexpress:

I plan to match them using the NanoVNA.  The Windows software for that has instructions on making a test jig (basically 4:1 matching transformers and 3db pads on either side of the crystal) and apparently has a mode to let you match crystals in batch.  But I got impatient and wanted to see what it would look like to just make one with the first four crystals I pulled.  The result is here

And the sweep on the NanoVNA as follows

The best I can tell, it is centered at 8.9978MHz with a 1.8KHz bandwidth (to the -3dB point), with a 2.48dB insertion loss.  Which isn't far off what I want (was aiming for a 2KHz bandwidth).  So all in all, a pretty good result I think?  I want to try again with NanoVNA Saver when I get a chance (to get better numbers/pictures) and I really should actually calibrate it :)  But it was a quick test when I had a few minutes between things. 

Edit: Got NanoVNA going, and calibrated.  I was pretty spot on before.

New Antenna - QRPGuys DS1

 I put together a QRPGuys DS1 antenna today.  Went together pretty well.  Really the only hard part was screwing in one of the BNC connectors (because I didn't have anything that was the right tool for holding one of the bolts).  I had to order a tap, and needed to pick up a few things at Home Depot.

Haven't had a chance to do much with it yet - just measured the SWR on 40m.  

Can't really see the NanoVNA screen here.  The SWR seemed to move a bit - probably because I was using a short coax and my body was affecting things.  When stable, it seemed to be about 1.1:1 at 7.058, and went up to 2:1 at 7.118.  So, overall a bit narrower than I would like, and possibly centered a bit low.  Will hopefully get to try WSPR on it soon.

Got a few minutes to fire it up in the backyard:

Not getting as far as I'm used to, but this is also not the best time of day (5pm in the afternoon).  

And I am definitely getting farther on my dipole

On the air

 Wanted to take my new paddle out for a spin, so broke out the QCX.  Tried calling for a while, but no takers.  The only people I was hearing were *really* fast or they were far away.  Ho hum.

I got three spots on reverse beacon network.  Had hoped I'd get more.  So broke out the GPS board and tried to see who could see me on WSPR.

Amp success!

 Playing around with the amp again from the other day, but this time *with* power to the driver...

And I'm getting a solid 5w out!  Exciting result!  Now, mind you, in LT Spice it was showing like 17W out, but I'm still excited with the result.  

Board is extremely messy, and wires are all over the place.  Need to decide if I want to clean this up and make it more permanent or not.  Also want to wind the QRP Labs LPF (as opposed to using the cwaz one I made years ago).

Also, isn't the red LED fun!

New paddle

 I 3d printed a new paddle.  Am pleased with it.

Here is the old/new together.

I am trying to make an ESP32 interface so I can do BLE to my iPhone so I can use it when I'm practicing on Morse-It, but so far it hasn't worked.  I managed to get it to be recognized on the wife's Windows laptop, but not on the iPhone/Mac.  I finally downloaded a program called "BLE Scanner", at which point I managed to get it to pair, but still can't get it to work with the morse program.  :/

UPDATE!

Is working now!  Still not sure why it wasn't showing up initially.  But the issue with sending seemed to be the 'delay' I had in there.  A longer one let it work, but then wasn't response enough.  (Only had the delay due to the example in the library I was using.)  Ended up rewriting using the debounce2 library, and am happy with the result.

Code is here

Now just need to design a box to print, etc.  May try to use a rechargeable battery I have to make it more portable.  (The Adafruit Huzzah32 has a built in LiPo charger with undervoltage protection).  All in all, result!

Playing around with a different irf510 setup

 Just wanted to get back to building again, so threw together something from a couple of sources.  Basically trying to bring up the Si5351 voltage to something, then put into a totem pole driver, and then into an IRF510.  In LTSpice it is working great (17w), but on the bench, not so much (1.5w).  The first driver section gives me what I want by itself, but when I put the totem pole on, it drops, so the transistor isn't turning on/off as hard and wasting power in between.  Might try to poke some more later, but may try a different approach.

EDIT: the whole "sleep on it" thing wins again.  Woke up early the next morning with my first thought being "you totally didn't connect Vcc to your driver".  Sure enough, I was so focused on triple checking the IRF510, I missed the power to the totem pole!  So I'm surprised I was getting anything at all out of it, much less 1.5w!  :)

I also was driving with a sine wave instead of a square wave like I intended.  Will need to go over my build and test again when I'm able to focus better...

Gate Driver Woes

 So, my current theory is that I blew both sides of one of my drivers and one side of the other.  I had the suggestion on the QRZ forum to look at the waveform output without any transistors attached.  On one of them I don't see anything on either output.  On the other I see on the "top" output only.  So guessing I blew something up.  Hm.

Homebrewed FT8 - Success!

Messed around with my antenna this morning.  It would look great, but pulling the feed line to the side a bit made the SWR go sad.  I brought it down and... just kind of messed with it.  Seems to be working now, but I'm not sure I could tell you what I did.  Tightening the N to BNC connection may have been it.

Anyway, had another go at it tonight, and managed to have a QSO!  WA6BJQ down south of me.  So exciting!  Also managed to get picked up all over.

Class D progress - April 10, 2021

 Based on some feedback from the QRZ forum, decided to move forward with a bifilar wound FT50-43 (six turns, 1:1).  Here is the result

Unfortunately, the smoke test let out smoke.  The bottom transistor (not pictured) blew.  I had wired the output transformer wrong, so thought that was the cause.  I put in another one, but it blew also.  My current theory is that I don't have enough decoupling capacitors in there, so the driver isn't able to drive the transistor well, so it is just staying partially on and burning up.  Will add some more and try again (though hopefully that works, because I only have one left!)

I wasn't sure about doing the IC adapters here (probably adds inductance and capacitance - hopefully not the problem I'm having), but being able to easily swap the chips is great.

April 9, 2021 - sort of progress

Someone on QRZ forum has been giving me advice on my Class D design I am working on.  I soldered the tiny, tiny parts onto their breakout boards - I should really avoid parts this small in the future...

I found in my design that the coefficient of mutual inductance plays a huge role in the performance, and I don't really know what that is reasonable to be.  So I decided to make a 1:1 toroid and measure it (based on a procedure in EMRFD).  However, I could not get my Banggood special inductance meter to work right.  It has in the past, but no love tonight.  So I decided to try the function generator/oscilloscope approach where I see where an inductor gives me half the voltage of a known resistor.  Worked well for the primary/secondary windings, but couldn't get it to work for the other connections the book has me do.  I assume the values are low and need to use a high frequency, and the frequency generator isn't very linear in its output over large ranges.  May try some other method here soon.

I tried FT8 again tonight, but didn't get picked up by many receivers.  I checked my signal into a dummy load afterwards (trying to figure out how much power I was putting out), and into a dummy load I was doing about a watt.  However, I see that I am drawing half the power into the dummy load than I am into the antenna, so I should check that again.  I might want to build a little matching network, even though the NanoVNA (the last I checked) seemed to show things fairly happy.

Homebrewed FT8 - Continued

 After having had success receiving and sending separately, today I put together the rest of the picture.  Printed a little box for the TR switch.  Quite pleased with how that turned out - first time I designed a box that closed.  Even chamfered the screw holes so the screws sat right.

Managed to get everything going (WSJT-X already had the patch the guy submitted, so was very easy to get up and running), but guess the conditions aren't as good as the other day.  Not getting a lot of spots, and definitely not making any contacts.  Will have to try a different night.  As an aside, I think my amp might trying to become an oscillator on occasion.  I keep an eye on the amperage of my bench power supply, and sometimes it isn't going back down to the quiescent current level.  Will have to revisit that.  As an aside, I am making great use of the cheap-o infrared thermometer I got for Christmas several years ago - way better than testing the transistors with my finger :)

FT8?

 I recently saw this post where the person made a cheap and cheerful FT8 setup using an Si5351/amplifier and an RTL-SDR.  I thought "hey, I have all those parts", so I thought I'd give it a go.

So far, I've done two parts.  After I got my dipole back up and tested it with the NanoVNA, I plugged my RTL-SDR in and got it working with WSJT-X.  I used a 40M bandpass filter I had built (because I had it), and got results right away.

For my later reference, my setup was

• CubicSDR on “direct sampling - Q"
• Tune to 7.074MHz *upper side band*, bandwidth ~3k
• Turn on Loopback, with the source being CubicSDR
• Turn on WSJT-X, pick “Loopback audio” as the input
• Set WSJT-X to be on 40M/7.074

Today I dug out the "Mighty Mike" amp I built some years back and verified it still worked.  Connected an Arduino to an Si5351 board, that into the amp, and that through a low-pass filter.

I used the software here and didn't use their other one that actually interfaced with WSJT-X yet, as that seems to need a patched version and didn't feel up for getting that to work yet.  As is, took me a bit to get it working, as there were a bunch of libraries I needed to install (wasn't clear which ones when I started), and I had trouble with the "weakmon" library it used (it was trying to load an ".so" file that it couldn't find.  Had to build that and then update the code to reference the exact path).  But after that saw their nice little terminal screen.

So just transmitted from there (not doing any receiving) and looked for myself on PSKReporter.  Bam.  Success!  I probably wasn't even putting out a watt, and my dipole is *really* low, so pretty stoked.

I need to build the relay TR they describe, and need to figure out how to get that patched version of WSJT-X working (as I really don't want to try to build that on my mac...), but that is a project for another day.