More Fun with Iron Donuts Part 3: Bigger is Better?

Is bigger better?
When talking about icecream and chocolate bars, I'm going with yes!
When talking camping gear and portable radio options, I'm thinking no...

 

Big Happy Iron Donut

I do own 2 QRO radios, only one of which works, the Swan 100-MX. Because I seem to be digging this EFHW design, I decided to up the ante so to speak, and try my hand at making a setup that was a little more robust, capable of handling 100+ watts.  When it comes to Transformers, that means bigger wire and bigger cores. The largest wire I have on hand is 22 gauge, which is big enough to handle 100w, if the match is good, and there's not a lot of core heating. At least I think it is, that's why we give things the ol' trial by fire so to speak. My thoughts were, get it right at QRP levels, and then go QRO.

I wound up the same transformer as The Micro-Matcher, only bigger. it has a 1:9 turns ratio, and is wound on an FT113-43 core. Poking around in the junque baggie of NP0 caps, I found another 150pf cap.

After wiring up the toroid, I hooked up the half wave 20m wire, and got portable. Well, battery powered at least:

OP ready to go, Rig is SW-20+ rated at around 1 watt on battery output.

We have a match!

Since the match looked pretty good, I figured I would go ahead and call CQ a few times to see if I could quickly scare up a QSO. No luck then, but I checked the RBN and there I was!

Notice the one entry from Nov 2? 

I moved the rig back inside, and hooked up to the bench power supply to give me that little extra bit of RF. Life intervened and I had to wait until my wife got home before really testing out the setup from inside the shack. Tuning around 20m I came across a CQ that lead to a QSO. Noticing a hike in the SWR when going through my tuner (even in Bypass mode), I began to suspect either a problem in the tuner or in the antenna switch.  I looked out the window, and discovered my problem. I was a little pressed for time (had to get ready for work) so I apologize for the brevity:

Funniest thing about it was that the SWR was still less than 2:1.

Testing at QRO levels is still ongoing. Things are promising, especially on 20m so far, but the jury is still out, and I need to buy some connectors, coax and PVC to check some things out.

73,
GB Hoyt
KG4GVL

World's Ugliest Dummy Load Part 2 (Caution Pic Heavy)

Only one of these is a Dummy Load

This is Part 2, Part 1 is HERE.
So I completed my Dummy load late Saturday Nite, early Sunday Morning. Here's how it went down.

All the parts.

I started with the dummy load, and added two wires to it. I decided to keep traditional colors to indicate which side goes where, think red positive, black negative, red goes to the center pin of the UHF connector, black to the ground side. In the picture on the left, the parts are (left to right) dummy load, UHF connector on jar lid, and Jar. Some folks put theirs in a paint can, but I put mine in a glass jar so as to see my handiwork. The jar is "recycled" (repurposed?) from our pantry. Coconut oil came in it originally.

Here are some closeups of the dummy load itself. They are as good as my phone camera could take :D

Purdy ain't she?

The underbelly is equally attractive. You can't really tell, but the pads are jumpered together using the resistor leads. I would pull the lead through one side and thread it through a hole two pads down to give the resistors up top space.















I attached the UHF connector to the top of the lid by drilling a hole in it, and rolling a lip onto the edge. It felt pretty snug once I got the connector fully seated on top. It was easy to hold the connector in place and use a 1/8 inch drill bit to drill out two of the holes for mounting screws. I searched in my junque drawer for the hardware, and settled for some bugle headed machine screws that fit down in the screwhole for the connecter. I also drilled out a hole for the ground wire to come up through. I wanted to be able to solder the wire to the top of the connector. Here's how it looked:

Ready for connection!



In the jar, but Dry.



After threading the ground wire through the hole to the top of the connector, and soldering it down, I soldered the red wire to the center pin of the connector on the underside. Before I put mineral oil in it, I wanted to make sure it was a 50 ohm resistive load. So I grabbed my trust $4 Volt Ohm Meter and started poking it.





It Works!


Yep, it works! I put mineral oil in the jar and sealed as tight as I could. Rechecked resistance, and it works!



Of course the real proof was in the measurement of forward and reflected power. The only accurate and calibrated meter I currently have is my trusty NoGAwatt QRP SWR/Reflectometer. I grabbed it, and powered up the SW-20 and the Killer Watt Radio. At 20m, there is no reflected power, neither does it reflect power at 40m. When I hooked it up to the 2m radio, though, there was beaucoup reflected power, my lil' Diawa crossed needle setup on that band indicated an SWR of 5:1. I wonder how much of that is due to poor construction technique.







This is 1.25 watts at 14.06ish MHz



Behold the Final Product in all Her fullsized glory!

Beautiful!

All that's missiing now is a label that says "World's Ugliest Dummyload" or something.

73,

Walking the Dark Side

Don't tell anybody, but....
since the second week in November...
I've been operating QRO. Not always, but most of the time.
Seriously, the QRPrat has been QRO, 100 watts even.
Mostly on 40m.
So here's the full story: I had been saving some money for a KX3 when I realized that I will probably not be able to just up and save the dough to get one. All of a sudden, on QRP-L, there came listed for sale a Swan 100MX for the right price. I was still a little short, but no worries, the owner hadn't had any interest in the radio, so he would let me put a down payment on the radio to hold it, and pay the rest when I had it.
Awesome! I love this hobby!
In the middle of August, my new old radio came to me, I opened a somewhat damaged box to reveal a damaged radio.  Thank you post office! Specifically, the rear part was dinged, in a manner that looked like radio death. I read the manual and hooked it up to the powersupply without turning it on. No smoke, smells, flashes, or explosions. So far, so good, I hooked the radio up to the antenna tuner, and the antenna tuner up to the 40m dipole I have deployed in the trees. Plugging in the Mic, I turned the knob to click it on, and Behold! There was noise. Sweet glorious noise. The receiver receives.
Peaking the Preselector for max racket on 40m, and making sure the tuner was also at max racket and in power measurement mode, I found a clear frequency, turned the radio to CW Vox (thats how you operate semi-breakin on a Swan 100MX), and made sure the mic gain was set all the way down. I wanted to gently break the news to my tuner that there was going to be some "real RF" coming down the pipe, and not "The Killer Watt" it was used to seeing. I pushed the mic key to produce a sidetone. Tone present, no power out! Just what I was hoping for. If I had power out right now, there would have been problems with the mic gain knob. Hey, this is a QRO rig, but it can be QRP when I want it to be. I began increasing mic gain, hoping to see the power needle move on my tuner...

No Dice.
No transmit.
No cookie, no joy in Mudville.
No DX chasing, no nuthin'...
NO POWER OUT
I was heart broken. I had saved so much, said no to a lot of things I wanted to get just so that I could save for this radio. When I saw the picture of what they looked like, I knew I wanted this rig. There's a guy on the west coast who keeps these things running, and according to him, I'd probably be looking at paying what I paid for the radio to get it fixed (side benefit being a complete alignment from a guy who's job was aligning these things when they were built!), so that option was out of the question for the moment.
Fortunately, the Swan 100MX is a real radio.
Let me 'splain what I mean.
Most people own appliances, not real radios. An appliance is something you use without knowing what's going on inside it. Appliances come with a lot of bells, whistles, capability and performance.
Real radios can have some of this, but most don't. Real radios are about the operator, and what the operator can do both with and too the radio. I'm not downing appliances here, my 2m and up gear is just about garaunteed to always be an appliance.  It's hard to build that stuff well without a precision oriented set up. It's done all the time, but not by me. Appliances tend to be most useful when it's vitally important to transmit information, but when I'm wanting to play radio, I want a real radio.
Popping the top on the rig was a breeze, and I was confronted with a beautiful example of what happens when someone designs a piece of electronic equipment with the expectation that the user will be poking around a bit under the hood. That's another hallmark of a real radio, you can use the radio while poking around in it. Here's a picture of my radio:



The Swan

  Notice the simple layout of the radio, Everything does what you think, no menu settings about it. 
Simplicity is beautiful, but meaningless if the radio doesn't transmit. I don't have a license so I can listen, I have one so I can talk back! Fortunately, the radio came with a full set of service schematics as well as the owner's manual. each section has its own board, and servicing the radio is as simple as popping open the hood,  finding out where the board you want to work on is, and "fiddlin' until fixed".
Did I say that was simple? heh.
Once I understood the layout of the radio, it became simple, first clear and obvious problem was the large ding on the back of the radio, so I began looking for problems on boards that were somehow attached to the back side of the radio, and I needed to somehow restraighten the chassis a bit. I figured the main problem was that whatever board was attached to the rear chassis had cracked a circuit trace, or shorted a part. I was nervous though because the ding was next to a large heat sink, and large heat sinks usually mean "Final Amplifier Section." sure enough, when I got the covers off, I could see that the finals board was mashed conspicuously against the filtering section. Yikes! Not good. The final amp transistors in this radio are no longer in production, if something has gone wrong with them, I'm beat!
The first thing I decided to do was replace the antenna connector. It has the standard SO-239 on the back, and replacing it was not all that much of a challenge. Replacing it also didn't affect the powerout at all.
GRRRRRRRR.
It was time to take rear off the chassis, and get to the bottom of the finals board.
Getting it all apart was no small feat, I had wires to bend (and break, and then reattach), screws to keep track of (hehe, babyfood jars to the rescue!), and then a schematic to puzzle over.
Things looked a little hinky right where rf entered the finals board. There was a driver and buffer amplifier there that looked all twited up, I'm pretty sure those transistor legs shouldn't be like that....
I poked and prodded with an orange peeler I've modified for use on radios. It's nonconductive, and once upon a time I needed something that could turn shielded inductor slugs, so, I wound up with this thing!
After making sure everything was bent back into place as well as I could get it, and that nothing was shorting anything out that wasn't supposed to be, I applied power to the rig, with the rig wide open. No spoke, no smells, no worries!
Time to see if I can transmit, and......
IT WORKED!
weeeeee!
Having too much fun, I did a little dance!
Now I have a QRO radio in the mix. I wish I had a true power meter, that way I could tell when I am QRP and when I am QRO with the swan!
Time to have fun...