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.

OTHER NEWS:
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.

73!
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