Monday, February 11, 2013

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


Friday, February 8, 2013

Twin Tube Operational Update

Been a while since I posted on the NoGA Twin Tube 80 (link opens the first article in the series, see Ham Radio Masterlinks for a list of all the articles), figured I'd post an update, and talk about some project ideas I have for this set up.
Not long after successfully using the transmitter, I ran into a difficulty. The next time I tried to use it, I powered the radio up, I got sparks when I keyed down! Hmmm, that's not right! I also was getting no power out.
I decided to give the rig a break for a lil' while, and focused my efforts elsewhere. Since I was going to be up, I took the transmitter back out, and began poking about.
2 months hadn't improved the situation, it still didn't work.
Power supply was good,
I suspected the transmitter had shorted something out when I tried to go poking about the last time I successfully used it, I wiggled wires, and mushed down parts. Still no dice.
I replaced the three 33pf capacitors and checked the 100microhenry inductor for continuity.
I then inspected the pins on the tube sockets, and sighed when I saw that pin 6 had a loose hookup wire.
hmmm, soldered that puppy down, made sure everything is bent to not short out, and closed the case back up. I think that the use of an Altoids tin in this situation is a mild gamble. It works decent enough, but there have been several times when I've come dangerously close to knocking something seriously out because the tin is somewhat flimsy when you begin poking holes in it.
I plugged the transmitter in, and things began to glow.
no Smoke, and no fires. That's a good sign.
Glow in the tube, antenna is a dummy load, DVM on, and keydown.
20V on the meter!
that's 1 watt folks.
we back in business!
The Thermionic Energy is Astounding!
These two glowing eyes
Voltage amplification
This is hollow state.

Of course, now I need to find someone to QSO with late at night on about 3582 KHz. The crystal is 3579.4 KHz, nominally, but it pulls a little higher in this circuit, I'm guessing that I need to add some capacitance somewhere to pull it back down. That gets me to my next point.
Back when I was building this thing, several suggestions for experiments were made to me, but it's not easy to swap parts out of this altoids tin. I've got a couple extra tubes that will work in this getup, and I'm thinking of building a breadboard that I can plug parts in and out of. I need some more tube bases first though.
The schematic is availble for view HERE. KL7H has done a great job of documenting this and Mike's 12 v regen project.
Any suggestions for substitutions?
Should I attempt to wire one tube as an oscillator and the other as an amplifier? (MOPA esque?)
Suggestions for boosting power?

Thursday, February 7, 2013

World's Ugliest Dummy Load Pt 1

In the last post I mentioned making a dummy load, and things not going quite as expected.
Things are turning out down right UGLY! LOL!
Pretty Is as Pretty Does
So far, it's going well, but when I got the leads prepped for adding a UHF connector, I found the Junque box fresh out! hmmm, I have plenty of BNC's but no UHF. Time for a trip to RadioSnack I guess.
I figured out what I'm doing wrong with this, and the solution. I tried adapting K4EAA's methodology, he uses a drilled brass plate to hold things together, I thought I was being slick using circuit boards. My problem came when I tried to line up the resistors to insert into the second board. Dadgum thing refused to go together!

I forgot this part in K4EAA's article:
Note on easy assembly - Solder all 20 resistors to one plate, and then, starting at one corner, and working toward the opposite corner, cut the lead lengths starting from your minimum length, to progressively longer as you work towards the opposite corner.  This will allow you to insert a few leads at a time as you combine the two plates.   If they are all the same length, it will be very hard indeed to thread the 20 resistor leads into the bottom plate!

My Daddy told me once that "Common sense isn't", and boy I relearn that lesson about every week, hi hi! In reality, I should have been listening to my inner voice that said "4 resistors on strips, like they come in bulk". I dismissed it as a dream, I don't have Dremel (generic or for real) so making strips out of PCB is tough. I tried cutting a double side PCB to make some paddles out of it, and it takes a LONG TIME with a hacksaw. I need to get a Dremel to finish that project. This morning I had my epiphany though. Being a QRP operator, I have an Altoids addiction. I claim I use them for the tins, but in reality, I just like munching the things down. As a result, I have a container that has nothing but Altoids tins in it.

Don't Judge, chances are you have one too.

So at some point in time in the nearer than the further future, I will be modifying this project.

1. I want to remake the dummy load with 3 watt resistors instead of 2 watts. That way I will have have a 100+ watt DRY Dummy load.  The nominal rating of this one is 88 watts (44 2 watt, 2.2KOhm resistors) I will probably order the resistors the same time I order some MV21's and binding posts to capture the Peak voltage of the circuit.  If I decide that the cost is too high, I may just reclaim the resistors off of this board. I don't think it will be too hard to get them all apart (famous last words, hi hi)

2. I will make it using strips of 4 resistors each (11 strips total). Airflow will be better, and appearance will be better. Fun to be had by all.

N8VCL has become a Kitbuilder!
See his excellent adventures assembling a NS-40. Note the lack of any iron donut winding. That's kitbuilding HERESY! :) Check out the video of his kit in action. I hope he QRVs and QSOs with it soon.
Looks to be a neat kit, and N8VCL (Scott) certainly did a better job than I did the first time I tried to assemble anything. He's been added to to the ham radio bloglist on the right panel.


Wednesday, February 6, 2013

Cliches and Operating

You that old saw, "It's not a failure if you Learn something"?
I've always hated that statement. I try to learn from my failures, but failure is failure, and for something to fail means that I wasted time doing something, and time is really my most precious commodity.
So here's what has failed, and here's what I've learned.
1. I wanted to build an antenna that would cover 10m, 20m, and 40m. I failed because I didn't understand the nature of what I was building. Instead of making it small wavelength to big wavelength, I needed to make the calculations for the whole antenna first, and build the whole thing, then tune from the smallest wavelength to the biggest wavelength.
2. I attempted to operate from the field (work parking lot) twice this last week, both times was a bust. My semi-success with the 4SQRP outing in October. I had to learn lessons there too, like, easy setup is more important than antenna efficiency in times of expediency. I think something like the St Louis vertical, or the St Louis Loop is a better choice for time sensitive ops, where the W3EDP is a better choice for times when you have time to set up. As an operational note, W1AW was 599 to my QTH on 40m Monday night.
3. Right now, I'm building a dummy load out of 2 watt resistors. 44 of them in parallel to be exact. Even that has had "Learning opportunities", namely when it comes to lining holes up. That has changed from being something pretty and elegant to downright ugly. I just want it to work.

Tonight, I think I might just go to bed, leave the soldering iron cold...
or maybe I won't...
stay tuned!

Saturday, February 2, 2013

Operating is the Trick

So my antenna woes continue at the home QTH. I've decided that the 10/20/40m dipole I'd been planning was a boondoggle, at least in the manner in which I had planned it out. I might be able to make something out of it but not before I get some more ladderline. I'm not cuttin' up what I have now because I can use it to depoly an all band no fuss "Double extended Zepp" type antler for 80m. I'll just run 450 ohm feedline for that sucker, and call it a day!
To get myself out of the ham radio doldrums, I decided to play radio from the field, well, kinda from the field at least, so it's time to operate KG4GVL from the work parking lot in the FYBO contest.
Ready to Deploy!

The antenna I decided to use is the W3EDP. I've featured  it several times on this blog, and it is my favorite antenna. I use a sister antenna to this one at home for my primary antenna right now. They are generally stealthy, simple to deploy, and tune well on all the bands, except 10 and 30. I've gotten them to tune there, but not without struggle. Getting it to deploy was a mild challenge, I arrived at work 15 minutes before I had to clock in just so that I could deploy the thing, and maybe even strike up a QSO or 2 before clocking in. Murphy struck a couple or three times, and I barely got the antenna up before clockin time.

Ready to Operate!

Notice the picture on the right? I'm using "The Killer Watt Radio", my trusty ZM-2 antenna tuner, battery power, and a straight key. I have the world's worst callsign for contests, but hey, I like it just fine for most of the hamming I do. In the middle of the lid is my "Highly Calibrated Whistle Thermometer." It will provide real time temperature readings, and serve as a handly emergency signalling device should the need arise.
Because I'm using "The Killer Watt Radio", I am stuck to 40m only. That's ok, but it's times like this I do miss having an FT-817.

Check out for KG4GVL when I get QRV!
Follow up Post to come later.