Great Time to Update the Hamshack

From Keith, W1KES

Last month, we repainted our bonus room, A.K.A. dad’s shack after 17 years. Additionally, we added new furniture and shelves. I have spent the last several weeks organizing and optimizing the space. My shack also serves as my home office, which has received more use this past week than the previous year. With kids out of school until mid-May, I plan to spend many hours working and “hamming” in my recently renovated space.

Before

After

 

From the Land of Magic – Solar Panel Load Controller

From the Land of Magic! a high tech solar panel load controller, built for son Pete. You can see that the latest components and construction methods are employed.

There’s a differential amp that drives an Ebay PWM speed controller ($11) to load the panels to their max power voltage, regardless of the insolaton* level. A sample of the panel voltage is compared to a Zener reference to generate the control signal to the PWM unit.The load is a 4500W water heater element in a tank in front of his regular water heater. There are three 235W panels with 29.4 V max power voltage.

I had a great talk with a dealer recently. It seems that PV power is now cheaper than heating water directly with wet panels. Cheaper panels and good inverters seem to have made a big difference.

Wilson, W4BOH

insolation* No that’s not a mispillin’  Insolation‘ is the solar radiation (power/Unit Area) that reaches the earth’s surface, which average high sun is close to 1KW/square meter.

Controller Schematic

A Better Mouse Trap or is that a CW Key?

Well I’m quite familar snap! with the Victor mouse trap after a recent bout of mice invading the garage and building nice little nests in the heater air intakes of not just one but two cars.. little buggers!

But, Ken AC4RD’s use of said device plus a couple Fender guitar picks and a wine bottle cork brings a whole new meaning to home brew! Always thought those wine bottle corks had another great use.

Click here for more !  https://kuzenski.org/mousetrap-paddles

Thanks, Ken!

Sheltering in Place due to the Coronavirus?

Featured

and want to stay in touch with your ham friends?

Show your friends your latest pride and joy project or any field of interest you would like to share with your ham friends.

How? Send an email to orange.county.radio.amateurs@gmail.com with attached photos, or a link to the photos you wish to share,  a brief description and I’ll post it on the OCRA website.

Dan, KR4UB

What is it?

Well lets see… a large open field, complete with shadow of another tower with 2 large beams (and climber down below)  A top-hat loaded 100′ tower for the 160m band that the owner plows in sixty-six 90 foot long radials for maximum performance.

Who else? Of course its the new N1LN 160m band antenna setup.

Kubota tractor with an attitude..

Plan to use an Inverter Generator or run your Field Day station from a generator?

Variable speed inverter based generators offer significant reduction in audible noise and fuel consumption. Most consumer quality, constant speed generators that typically run at 3600 rpm are noisy and consume much more fuel.

  • The small inverter generators are well suited for Field Day due to their lower acoustic noise profile, provided their AC output is filtered to eliminate RF noise typically occuring in the 80m band.
  • Using short AC cords with no filter on an inverter based generator still presents unacceptable noise on 80M.
  • With no filter, detectable noise on the 40m through 10m bands was not found with the Honda generator shown in the next article below.
  • The RF noise filter in the next article using 3 large 4″ OD Fair-rite mix 31 toroid cores has been proven in a series of EMI test configurations to be effective in eliminating inverter generator noise. The complete, enclosed filter including a GFCI outlet with in-use rated cover for outdoor use, costs around $150 to build.

The degree of interferenence to an 80m station from an inverter based generator & attached cord radiated RF noise coupling into the Field Day antenna will vary somewhat based on the station physical arrangement. The graphs below are the received signal into an 80M station antenna located up 55 feet in the air, with a 50 foot drop cord lying on the ground underneath a portion of the antenna that connects the generator to the load.

Thinking about running your Field Day station directly off a generator and not using batteries?

There has been discussion of eliminating batteries all together (as the Field Day rules permit) and run the station on a small generator. Tests should be done before Field Day with the specific AC to DC power supply and generator to be used to determine if the fluctuating loads of a CW/SSB transmitter is going to cause deep fluctuations in generator engine speed.

Why would one care?  Most hams know that with synchronous (aka constant speed) generators the frequency output is determined by the speed the armature is rotating, and the number of poles in the armature.  What may not be known is that the raw voltage output of the generator winding varies proportionally with speed at which it passes through the magnetic field (aka armature rpm). That’s why all synchronous generators have a voltage regulator circuit that adjusts the other variable affecting voltage output, the strength of the magnetic field.  The question is how well in a consumer quality generator does the voltage regulator and, the mechanical engine speed governor handle wild fluctuations in electrical load.

Rather than using mechnical speed governors, commercial large scale generators use electronic throttle control systems for more precise control of engine speed by comparing generator output frequency to the throttle controller’s internal 60Hz frequency standard.

Rather than expose expensive radios and DC power supplies to such effects,  one fix could be to still use a battery or two in the 12VDC circuit to buffer the generator from the wildly fluctuating loads such as a CW transmitter.

A Power Line Filter for an Inverter Generator

Dan, KR4UB

After viewing a recent ARRL youtube video regarding RF noise that can be generated by inverter based generators, I decided to do some testing of my Honda eu2200i inverter generator, a later model, slightly higher capacity unit compared to the Honda generator in the ARRL youtube video.

First Impressions

The RF noise characteristics of the eu2200i unit do not seem as pronounced as demonstrated in the ARRL video, although that could be due to test configuration differences. It was noticed in the video that their antenna was very low and close to the generators. The horizontal loop and dipole antennas at home used in this testing are at an approximate 55 foot height over the test area.

  • The only amateur band that had generator noise was 80 meters and was loud enough to be an issue for Field Day.
  • Reducing the generator load helps reduce radiated RF noise.
  • Using a shorter drop cord can help, but not enough to eliminate generator inverter radiated noise.

Line Filter Project

Given the club’s Field Day plans to run in a higher RF power output class with the associated higher battery draw, the two transmitters of the combined 10m/6m stations I help set up and operate will be especially demanding on the batteries. If the Honda inverter generator is to be used to recharge this station’s batteries, a fix is needed to eliminate the possibility of RF interference to nearby field day stations.

The first step of the project began with a conversation with Howie, WA4PSC ProAudio Engineering who stocks the Fair-Rite toroid cores, regarding the best choice of ferrite toroids. His recommendation was the Fair-Rite 4.0” OD x 1″ H mix 31 units, given the frequency range at issue and will permit larger spacing between turns for less capacitive coupling.

The test configuration consists of the Honda inverter generator, drop cord and the power load placed beneath my HF horizontal loop antenna located approximately 55’ overhead. It was also in the vicinity of a dipole antenna also at 55’ above ground. Noise was observed on an Elecraft K3s and a SDRPlay 1a SDR receiver both using the same antenna. All displays of received noise below are from the SDRPlay 1a SDRuno application.

The generator test load is a 1500 watt electric heater, connected to the generator by a 50’ long drop cord. Several orientations of the drop cord were tried and as expected, there is an observable difference in received radiated noise based on drop cord orientation.

Two filter configurations were tested using different toroid winding configurations, both using three of the Fair-Rite 4″ OD x 3″ ID x 1″ L 2631814002 toroids.

Toroid Configuration #1

Not knowing whether the preponderance of the Honda inverter generator noise was common mode or differential mode, the first test was with toroid #1 wound with both neutral and the hot lead in a common mode attenuation configuration and then toroids #2 & #3 used as follows. Toroid #2 was for neutral & ground, wound for differential mode attenuation and toroid #3 for the hot lead similarly wound for differential mode attenuation. This configuration was not very effective in reducing the observed noise.

Toroid Configuration #2

Not satisfied with the above result, the toroids were all rewound for common mode attenuation as shown below:

The hot and neutral lines are wound on two toroids “in series” and the ground wire which can also be driven by common mode noise is on a separate toroid.

The “missing” (or more widely spaced turns you see in the photo below (at the top & bottom of each toroid) were required for these 4″ OD toroids to fit in the 4″ deep box and permit the cover to go back on. As shown the larger 4” OD toroids permit wider spacing between the turns and thus reduce capacitive through coupling across the turns.

One detail on the unfinished design above will be to bring out a ground wire stud for connection to a ground rod to be located near the generator.

RF Noise Test Results

Using a real world 80m antenna as the test reference for radiated RF generator noise is not ideal in determining any absolute noise level reduction by the filter given the typical high 80M noise floor. But it does reflect the real world of a typical Field Day station setup.

The unfiltered RF noise of the generator driving a 1500 watt load via a 50’ drop cord is shown below in the bandscope display of my SDR receiver connected to the horizontal loop antenna. The display shows the frequencies (the repeating blue bands) and correlating waves of increased noise across the noise floor of the 80m band. Using AM detector mode, the noise is audibly loud; however in LSB detection mode the noise is not audibly loud, just a higher background impulse type sound. While there were some signals on the band, only one (the orange line) was strong enough to show above the elevated noise floor.

Below is a sweep of the ambient 80m noise level without the generator running and, ironically during a widespread AC power outage that occurred February 07, 2020. The amateur radio station is powered directly by a large battery bank and the computer for this testing is on a high quality (and very low generated noise) UPS designed for the commercial market sector.

To illustrate the effect of generator load or lack of, on radiated noise, the 80m radiated noise shown below is with the same configuration as the first chart, i.e. the 50 foot cord attached, no filter, and no electrical load on the generator.

Finally, the noise filter effectiveness of Toroid Configuration #2 is shown below. The measurement below is with the same 1500 watt load, connected through the 50 foot drop cord, but with the filter inserted at the generator as shown on the next page. Compared to the first chart with no filtering, none of the repeating blue bands and correlating waves of increased noise are present across the 80m spectrum. No interference was found on the 40m – 10m ham bands or adjacent frequency bands. The multi colored traces are 80m stations active during the measurement.

Throughout the test, care was taken to keep all connected equipment and the drop cord in the same physical configuration. Earlier testing showed drop cord orientation (and of course length) can make a considerable difference in results.

Filter at the grounded generator & 50 foot cord connecting the 1500 watt load

Final filter design

Below is the final design using toroid configuration #2, with a GFCI outlet and stud bolt connection for ground included. The stud bolt ground is connected to the GFCI electrical outlet ground and goes to the generator electrical outlet via the plug connected cable green wire. Per Honda documentation the outlet ground is internally connected to the generator frame components.

While test results show this filter to provide effective RF noise reduction with the Honda eu2200i inverter generator, other similar style inverter generators may present a different situation due to possible different power transistor technology and inverter switching rise times.

PostScript
A postscript is an afterthought, thought of occurring after the letter has been written and signed.
In discussing this filter with a few folks the conversation tends to turn to why this or why not that. The first EMI solution that works may be expensive and may not be the only design solution. Such is the world of EMI. The filter I built works, but with the included GFCI and other parts, is a bit pricey, approaching $140.00.  Would the smaller less expensive 2.4″ OD ferrites do the job? Testing of a filter using 3 of the 2.4″ OD cores proved the smaller cores to be ineffective. This is most likely from capacitive coupling of the closer wire turn spacing forced by the smaller diameter cores, or perhaps the core cross sectional area yields a magnetic flux path just too small for the amount of RF energy to be absorbed at the lower HF frequencies. Perhaps using only two 4″ OD toroids (eliminating the separate green wire ground toroid) might work, but hasn’t been tested.

Time spent learning what others have learned is always a worthwhile endeavor. Howie, WA4PSC of  ProAudio Engineering also passed on some excellent references for further reading. Jim Brown K9YC’s 60 years in ham radio, vice chair of AES Standards Committee working group on EMC and extensive research in the pro audio world is an excellent reference source. Jim’s  59 page “summary” reference document is well worth spending the time on the details of rf filter design. The filter design in this article correllates well with information his document regarding filters for the lower HF bands; e.g.two cores “in series”… check! … seven or more turns per mix 31 core… check! and choking the green wire ground… check, no out of sequence turns on the core… check!  Jim’s other publications can be found here.

46 SDR frequency sweeps, involving a number of test configurations, variation in filter components & design and involving considerable time were performed on this project looking for a better magic bullet. It did confirm the filter design in this article performed superbly over a number of test configurations, but no magic bullets were found.

Morse Trainer Kit Build; What Happened, and What’s Next?

by Steve, KZ1X

At the OCRA meeting (14 Oct 2019) there was a group build session for assembling the K1EL Morse Tutor kit club project.

Of the 25 or so kits involved in the project, approximately 6 were completed prior to the meeting! Those are our eager builders, and we’re lucky to have folks like that here to learn from. So few areas have such a rich experienced resource these days.

Another approximately 13 kits were assembled at the event.

More than a few assemblers were first-time kit builders, so, they get a special shout-out, as do the several experienced mentors present whose help was invaluable.

Since the success rate for the kits was effectively 100%, we can move to discussion of an evaluation of the event, and some next steps.

To start … It did seem like the participants were fully engaged and either re-learning their assembly skills, or experiencing them for the first time. This is certainly a good thing!

It would be great to get some additional and candid feedback on what went well – and what could be improved for some possible future event like this. Please feel free to share here or via direct email.

Now that many people have these kits built and operating, what comes next?

Several things, in fact, come next.

Immediately, please try and familiarize yourself with the settings on the Morse Trainer units you built. Pay particular attention to the setting that lets you control the sound pitch (tone) of the sending. You will want/need to be able to change this.

Also, work on learning TO CLEARLY SEND the first four letters of the lessons: E, T, A and N. Don’t worry about speed, it’s the smoothness that’s important to get down pat.

If you need to hear what these letters should sound like, I will be ‘playing’ them on the air, just after the ARES nets on Saturday mornings.

Lastly, don’t forget to remove the power jumper on your Morse Tutor when not in use, since the battery will drain if left on. That would take a month or two, but, no sense in running the batteries down for no reason. Simply unplug the jumper from the two pins and then re-seat it on just one, so you won’t lose it.

After that …

    1. The intent has been all along to offer weekly Morse tutoring lessons over-the-air via the 442.150 repeater … and in fact these were originally intended to start around now. There have been several setbacks to this plan, delaying the rollout by multiple weeks. I ask forbearance, all successful ventures take more time than originally anticipated.
    2. Group study events … did anyone notice the special feature of this kit, which allows people to pair-off and send Morse to each other in small group settings? The kits have a common RCA type jack on them, and with a simple phono male-male cable (which the club has several of if you don’t) they can be connected directly together! The MOST productive way to learn Morse is to first master a handful of characters (that is the purpose of the over-the-air sessions), make up words using just those letters, then send the code to a partner for practice. Then, reverse the listener and sender. These study events can be as few as two people, or up to MANY, and should take about 20 minutes each. The only catch is that there needs to be someplace people can go and have a quiet place for the study session. We’re spread over a very wide geographic area so this becomes challenging to manage. In an ideal world, we’d all have a weekly lesson session, and nobody would miss one. More realistically, those sincerely interested in learning the code can work with a buddy, perhaps one closer by than further, and help each other out getting to learn all 26 letters, ten digits, and a few punctuation and prosign characters.
    3. Computer aided training … there is Morse tutorial available called G4FON (the call sign UK ham who originally came up with it) and it’s available for PC, Mac, tablets, phones, you name it.In the next week or two I will send more information about this software and how to set it up to complement the coming training sessions.

For now… here are some links, see if you can install this software in your favorite device, and please report all successes or any gotchas:

http://www.g4fon.net/CW%20Trainer.htm for Windows
https://apps.apple.com/us/app/morse-elmer/id414371107 Apple iOS
https://play.google.com/store/apps/details?id=net.iz2uuf.cwkoch&hl=en_US Android OS

73

Steve KZ1X

Fall 2019 OCRA Club Construction Project

by Steve KZ1X

A few months ago I conducted an email ‘straw poll’ to gauge the interest in a club construction project.

It has been quite some time since the last such project.

The target date proposed for this project is the October 14, 2019 OCRA meeting.

This year’s idea was to build a very simple, but great quality and low cost Morse tutor keyer kit, and to back it up with over-the-air Morse lessons at some later date.

Response

The interest level in the kit itself was rather high, approximately 21 persons, and then others responding in ways other than via email. Some persons responding are DFMA members, as the email went out on the joint mail reflector.

Perhaps half the responders expressed concern about their electronics assembly skills.

They either were interested but felt it might be too complicated, many have never done anything like this before, they lacked the tools, were worried about success, or how to troubleshoot, needed help, and so forth.

Morse classes

The interest level in the Morse lessons was also high, higher than I expected. Some people wanted to get more proficient at their existing Morse skills and others wanted to learn from scratch. Still others already have Morse skills but just wanted to build the little kit!

Addressing the Concerns

To address the kit building concerns, at least two and possibly several more assembly workstations will be set up at the OCRA club meeting site, which for this session could start 30 minutes earlier than normal. The extra time would allow for everyone who wanted to, to get a chance to assemble and test his or her keyer.

Plenty of experienced builders are in the club and plan to attend this meeting, so there will not be any shortage of assistance.

To make sure the vendor can get the kits out in time, do not wait until just days before the event to order yours!

Project FAQ

  • Who makes this kit?

A small New Hampshire firm headed up by K1EL, a very well known ham whose call is almost synonymous with Morse keyer accessories.

  • How do you get a kit?

Order it from the link below.

  • How much does it cost?

The price currently is $22 plus shipping. The vendor is selling the kits quite near his raw parts cost, to assure it stays popular among newcomers to Morse. Another product sold by the same vendor, with similar functionality, costs almost 5 times this price.

  • How long does it take to get the kit?

About 4 or 5 days, here in NC. It comes USPS.

  • What else do you need to make the kit work?

Three AA size alkaline cells.

  • What tools do I need?

It is best to have needle nose pliers, a small flush cutter, solder, and a temperature-controlled soldering station. These links are just high-quality suggestions, for those wishing to equip one’s own new workbench. There will be tools available at the club meeting.

  • How long does it take to build?

Between 15 – 45 minutes, depending on skill level, equipment, pace, etc.

  • Are there any surface-mount type parts in the kit?

No.

  • What happens if it does not work?

That is not likely to happen, if you build yours at the club meeting there is a near zero chance to have this kit not work.

  • Can I get my kit and build it myself before the meeting?

Yes, of course, and then you can help others!

  • What do you get in the kit?

All the parts needed to make one complete keyer assembly, except for the AA cells.

The vendor also answers many of these questions, of course, including a complete description of what the keyer does.

Check out the kit web page at this URL:

https://www.hamcrafters2.com/K16tutor.html

Here is a picture of the box as it comes from the vendor, located in New Hampshire.

The keyboard and mouse are shown for scale.

Inside the small white box are the circuit board and a bag with the parts needed to assemble the unit.

Here is what the unpopulated circuit board looks like, as you get it. (Yes, the AA cell holder is already mechanically attached, but NOT soldered.)

The bottom side of this circuit board, where the soldering takes place, looks like this:

There are approximately 54 individual solder connections to make.

Here is the bag of parts:

and when assembled, it looks like this:

The assembly manual is available from the link above, and there is a button to click to place your order.

Please post any questions you may have to the OCRA-DFMA reflector.

Looking forward to the October 14, 2019 club meeting and the construction project.

Steve KZ1X

Point me in the right direction

Dan KR4UB accepted the satellite challenge for Field Day, a noble challenge indeed.  Aiding his effort, Dan reclaimed and repurposed available parts and materials to build an industrial strength satellite antenna boom…materials and instructions follow.  Nicely done Dan!

  • army surveyors tripod non magnetic construction, no ferrous metals added below to disturb compass reading.
  • left over 2″ PVC electrical conduit and elbow..
  • some ironwood strips inside the PVC to take the floppy/flexy out and balance out weight of antenna.
  • wood doweling, epoxy, brass screws to reinforce compass support elbow butt glue joint onto PVC elbow
  • good quality surveyor’s compass bought to rough out new boundaries when  purchasing adjoining land some years back
  • section of left over central vacuum cleaner return pipe (near perfect fit over PVC electrical pipe).. rotates for quick antenna polarization adjustment.
  • Brass  screws (where used) so no ferrous metal near compass
  • Arrow VHF/UHF gamma matched antenna. The foam covered handle fits perfectly inside the end of the 2″ dia PVC electrical conduit used as the boom.
  • powered by arm-strong…..