2018 CQ WW DX Contest

Almost missed the CQ WW DX contest this weekend. As usual I joined in as a casual search and pounce operator. Interesting results being at the low part of the solar cycle as compared to 2017. This year Solar flux was 68 and there were no sunspots. Even with these conditions the bandscope on the IC-7300 was full of activity. I started operating on Friday evening so my initial contacts were on 40m. Picked it up again on Saturday afternoon expecting 20m to be the main band. Indeed there was quite a bit of activity on 20m but conditions were difficult and it was hard to break through pile-ups. I switched to 15m and had much better luck there. 15m was the key band for me on this contest during daylight hours. late in the afternoon I tried 10m and was able to make quite a few contacts to South America.

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Last year my final score was 28,028 points with 121 QSO’s, 35 Zones and 63 Cty. My unofficial score this year was 33,936 points with 114 QSO’s, 42 zones and 70 Cty.

Europe was heard but very difficult to work. Japan was pretty consistent on both 20m and 40m. I could hear China (weakly) & Indonesia for the first time. The bulk of contacts were to central & South America and around the Caribbean.

So not a bad weekend considering I worked the contest for fewer hours and made fewer QSO’s. 20m continues to be somewhat disappointing performance but 15m was hot. ARRL SSB Sweepstakes is coming up in a few weeks and I plan to setup a 20m Inverted V with feedpoint at 10m for daylight work.

 

 

 

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Sense Antenna Mount

I have been using a rabbit ear antenna as a sense antenna for the Timewave ANC-4 Noise canceller. I printed a simple clip-on antenna mount for this as it kept falling off. Simple little gizmo.

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Case for uBITX

Printed a case for the uBITX transciever in White PLA. This was by far the largest and longest prints I have ever run. It is in three parts and took about 24 hours total time to print:

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A microphone case is currently printing and will be followed by 3D printed knobs for volume and the VFO encoder. I am looking forward to building this upand playing with the new rig.

3D Printed Power Pole Block

I printed a stackable Power Pole breakout box for use in portable operations. This is likely one of the cleanest prints I have done thus far. My print quality has improved dramatically since I switched to Simply3D software. Here are some pictures of the build:

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This is a really nice design and results in a really useful gadget for portable operations.

Hard Drive Gives Up the Ghost

I had mentioned some time back that the hard drive on my HP Z400 workstation was warning of read errors and would likely fail soon. I bought a new WD drive and had it on standby and backed up the old drive. The drive finally failed completely and I was forced to make the system swaps I had planned. Due to the nature of my desk, which I use as a ham shack, workbench and work desk, I had to spend almost an entire Saturday to move, disconnect & clean just to get the old PC out from behind the desk. I pulled out the HP Z400 (dang things weigh over 30 pounds!) and replaced it with the used HP Z620 I had bought a couple of months ago. This is a Xeon machine with 8 cores, 16BG RAM, and RAID 1 drives. Once everything was put back in place I had to reconfigure all my software. There were some instabilities at first but they seems ed to be related to the SDRPlay RP1 driver. Haven’t figured that out yet.

I opened up the Z400 cleaned the dust bunnies out and replaced the drive with the new one then reinstalled Windows 7 and loaded it up with 3D printing applications. This is now running the Creality CR-10S. The old Emachines PC I used on this before will go on ice until such time as I have a CNC machine to drive.

Had some problems with some of the software I run on these machines. Fusion 360 would not install properly. Autodesk help forum found a solution within 24 hours. So long story short, My workstations are back up and with better performance.

First 3D Printed Capacitor Experiment

Here is a 3D printed test piece to evaluate the dielectric properties of 3D printed PLA:

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I set this up with 1″ of engagement and read 12.5pF. When fully disengaged I was reading around 3pF. This is comparable with the properties of PE The dielectric test piece was printed with 30% infill. Next I’ll try this again with 100% infill and see if there is a difference.

UPDATE: Printed the dielectric part with 100% infill and remeasured. The capacitance went up to 14pF with 1″ of engagement. This would suggest a dielectric constant of about 2.6. This is somewhat lower than the only reference I found PLA with a dielectric constant of 3.1. I have not been able to find much literature on dielectric strength of PLA but given it’s dielectric constant would suggest it would be enough to support the voltages of a mag loop operating at 100W (~4.5kV).

With this data in hand, I will proceed to refine my capacitor design and print a functional prototype for my existing Magnetic Loop Antenna.

 

Redesigned Capacitor and Experiments Planned

As I mentioned in the last post, I believe it is possible to 3D print the dielectric used in my cylindrical variable capacitor such that it becomes part of the structure. The only concern I have with this is that the dielectric constant is likely to change depending on the amount of infill I use when printing. Infill is a percentage specification of how much plastic will be used in each layer. Typically I use anywhere from 15% to about 60% depending on the strength I need for the part. In this case, I am not after strength, I am after maintaining  a constant dielectric constant and voltage breakdown. I will likely buy some copper and print some test pieces this weekend to test things out with various infills.

I have a preliminary design to show what the 3D printed capacitor would look like including a stepper motor mounted to provide remote tuning:

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As you can see this is very similar in layout to the PVC pipe prototype made last year.

Rethinking the Cylindrical HV Variable Capacitor

I have been doing quite a bit of 3D printing lately and have been making various gadgets for the Office/Shack. I just completed a set of mounting brackets that mount an old Ipad 2 to my workstation just below the PC monitor. I can use this as a secondary screen or as a TV to monitor news etc.

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The¬† red “Whale tail” is a stand for my phone. Both of these items have opened up a lot of space on my physical desktop and were fun to build. I have also built adapters to mount the mag loop and homebrew buddistick to a camera tripod:

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Building these has allowed me to practice with Fusion 360 and I am feeling more confident in using it for design work.

These projects have got me to thinking on how the 3D printer could improve on my cylindrical HV capacitor design I previously discussed:

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I am thinking of designing custom 3D printed components for this design and possibly adding motorized control. I am also considering the possibility of replacing the PE sheet as a dielectric with a printed sleeve of PLA material. Looking up the dielectric constants and see how it would work out.

Summer Season Officially Over…Sort of…

Labor day is now behind us marking the “official” end of the 2018 summer. The temperatures outside, while still hot, are starting to come down slowly and there is actually a good chance of rain in the forecast. The weather will start getting good for antenna projects.

So I have some projects on the back burner that I am going to start working on soon. First up is trying a satellite contact with the arrow antenna and a Baofeng HT.  I just need to get my HT programmed to start trying this out.

I have also ordered a uBITX board from HFsignals.org. The uBITX is a SSB/CW transceiver for 160m – 10m at a 10W level. Nice homebrew and tinker project that hopefully will allow me to make contacts at places I would not normally take by FT-817ND (i.e., the beach).

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I plan to 3D print a custom case for this rig.

Also can report that I have updated the programming of the TYT MD-380 DMR HT this weekend. This adds coverage for most of the valley on DMR now.

Back on the Air for NA QSO Party

Unbelievable that I have been so busy as to not make a QSO in a month. Wow! That life thing….

Did some casual operating today on 20m for the North Americao QSO party. Nice to see everything was still working! I probably should take down the S9 vertical for some routine maintenance but it is just to darn hot! The canicula ends on the 24th so I expect the weather should be more reasonable after that. I continue to 3D print some radio components and have a big project in mind for a portable hexbeam. More to come.