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Iowa High Altitude Balloon Launch #4

The iHAB-4 launch last Saturday was oddly enough close enough to my QTH (51 miles away– in Oxford, IA just east of Iowa City, IA) to justify taking the kids to.  It also happened to be sponsored by the Marion Home School Assistance program (Marion, IA) that my children happened to be open enrolled in. Yes, on top of everything else (having four, young, non-genetically related South Korean adoptees) we homeschool our children.

This was a great way of trying to interest kids in Amateur Radio. I’ve been taking my oldest two boys (9 and 10) to a Technician Class with the hopes that eventually between that class and me teaching them the material that at least one of them would get a Technician license. Yes, they are a little young, but I think they could do it. (After all, they are homeschooled.)   Unfortunately, they have been very antsy.. I think I will get at least one to pass.. but maybe that will take months more.. maybe years more?

They like hamfests… but they LOVED this launch…

It is difficult to keep kids interested in DXing, Contesting, building antennas, etc. But launching a balloon is a different story.

This should remind us all that Amateur Radio is a very diverse hobby with many aspects. Marshall Dias, W0OTM of Ottumwa, IA I believe became a ham to fly the types of communications payloads that he does fly on the iHAB missions.

You can see what this leads to:

iHAB communitcations trailer

Serious hardware for the balloon experiments

And, you can see a “Serious ham’s” equipment inside of the trailer:

Inside of the iHAB Communications Trailer

Of course, the payload boxes are even more interesting than the trailer.  Again, this shows how serious even this unusual aspect of the hobby can be technically!

iHAB-4 Top Payload

iHAB-4 Top most payload - APRS 2m Beacon and 20m CW Beacon

As you can tell, Marshall W0OTM is an extremely positive guy and one could genuinely tell he enjoyed the involvement of the children.  My kids, with the important task of keeping the payload boxes from blowing away in the 25 MPH (with gusts over 30) Iowa nasty spring winds we thrilled to have the task.

The picture above showed my 9 year old son helping steady the top payload from blowing away.. the picture below shows my 10 year old (yes he’s shorter and smaller) doing the same with the bottom payload.  One of the experiments on this launch were separating the two payloads and running the antennas vertical between the two payloads.  It was probably a success on 20m, but it proved to be a bad idea on the parrot repeater (and maybe the APRS?) because when the balloon was above about 10,000 ft. the stations on the ground in Iowa were in the antennas deep null!

iHAB-4 Bottom Payload

The payloads are a clever version of simple technology:  Here is an example:

iHAB-4 20m CW Beacon inside the payload box

The equipment inside the payload is decidedly low-tech.  I actually decided to show the 20m beacon as it is probably the most custom piece of hardware in the whole balloon.  The repeaters and APRS transmitters are literally Alinco small Handi-Talkies.

Marshall is not an electrical engineer.  He’s willing to fly payloads that the ham community provides.  (So build something for him!)  Personally, if I had time (which I don’t) I’d like to do a SDR ARISSat-1 style linear transponder with the APRS beacon as the transponder beacon.  Marshall also said that he has most or all of the equipment to do a crossband FM repeater.  But he believes the “parrot” repeater is more accessible to hams.  I think it’s rather awkward to operate through.  Maybe the community can convince him not to fear 70cm.  I worked the parrot repeater with a $99 TYT dual band HT.  Dual band FM rigs are cheap now!

The main point, though is the science and the “WOW!” factor of the event for the kids.  Actually the iHAB-4 launch was probably the least technically successful launches that he did– really.. almost nothing on it worked fully correctly!  But the specific involvement of the children on this launch made the event really special.  Marshall, W0OTM should be lauded for his willingness to cooperate with the homeschool assistance program and his utter excitement and positive energy was an inspiration to my kids– and all of the kids at the event.

He also reminded me, now 25 years into the hobby and — even though I am only 42 years old– I am definitely a curmudgeon and a OF…   the excitement I had early in my ham radio experience.  I suppose I need to try to recapture some of that.

The event was covered by the local newspaper (the Cedar Rapids Gazette) and their associated TV station KCRG-TV (Channel 9) in Cedar Rapids.  So there was very good positive advertising for the hobby with this event.

KCRG-TV 9 report on iHAB-4 launch — video on You Tube

Yes, my children and I seriously get our 15 seconds of fame here.

There are a lot of primary source info about this event on the website at the following link:

Of course who are these goofy people posed by the fully inflated and ready to go:

The Motley Balloon Observation crewe

The Motley Balloon Observation crewe

4/6 of the Spinner clan.  My youngest son and my wife stayed home to be the remote “mission control” for us!

On the Shoulders of Giants

I really can’t believe I was invited to post here on   I tend to be brutally honest and not very politically correct or savvy and I figured it was more likely I’d upset someone here than be invited to post.

I do already have a website (a bit out of date, albeit) and a blog (which I will reserve for lengthy and very technical posts or ones I don’t think are of general interest).  But I will try to post here first.  Lets make the best of it regardless, shouldn’t we?

Spring is very rough for me in the free time department.  I have to “un-winterize” everything and do “honey-dos” and the antenna projects, and then other ham projects/operating which always seems to come last  :(.  So likely with my other ‘blog, you’ll see more in the winter than in the summer from me!

This weekend was typical Iowa in that the weather was actually very nice, but the threat of very violent weather and actually too strong of winds to do much productive work hurt the schedule a bit– pushed everything out another weekend… sigh…

Anyway, I digress.. I was asked by Matt W1MST to try to have some microwave, 1+ GHz plus material here.  I have to be honest, I am a VHF+er by heart and most of my 25 years licensed, but only in the last year did I get decent HF antennas, so lately my interest is in HF and (even though I said I never would) contesting and paper chasing.  I figure it’s time I tried it.  So if any DX wants to work me or ND (ZERO in the ND QSO party, dudes, what’s up with that?  I worked a bunch of rare DX that weekend but no ND?  huh?),  SD, MN, NV, WY.. e-mail me and set up a sked!  🙂  But I suspect that I’ll post mostly HF stuff for awhile.  Help me get WAS and DXCC if you want to see more microwave stuff!  (I’m sure VUCC would be next.  Like I said “cocaine” would likely be a cheaper hobby!)

But for my first post I’m going to document something not invented by me nor even yet built by me.

  Especially in Engineering, good engineers “engineer”, great ones “steal”.  There are many “giants” in amateur radio.. the best thing we can do is build on their legacy.

Here is probably the least expensive way to get a couple of watts on 10 GHz.  This amplifier was designed and built by Jerry Seefeld, WA9O who builds his own solid state QRO station on VHF/UHF and Microwave– several hundred of watts combined on each band, and runs it from the trunk of his car as a QRO rover! I’m not there and wasn’t when I roved.  What can I say.. his stuff is seriously hard core and really, really good…

This is his 10 GHz amplifier:  It turns out that the “FET” that is used in the Down East Microwave 10 GHz amp, is really a MMIC and has internal matching in it.   The part is available from DEMI currently for $110, the part number is FMM5061VF, it’s a Eudyna (formally Fujitsu Semiconductor) part.  It turns out that this device’s width is the same size as the width of two SMA’s mounted close together.  Since the device is a MMIC with internal input/output matching, only biasing and simple grounding is needed to complete the amplifier.

With some very careful machining and a breadboarded negative bias circuit, this device can be used without a printed circuit board.

This is the view of the device mounted between two SMAs.  Bypassing and grounding of the device is accomplished by “bubbles” in the copper tape and convenient soldering points.

Here is a view of the “top” of the amp:

WA9O 10 GHz Amplifer NO PCB, connector side

Here is a view of the bias circuit schematic.  Comments from WA9O on this will be posted at the end of this blog post.

And finally the business side of the amplifier with the bias board installed:

Here are Jerry’s comments about this circuit.

The P channel IRF9530 has a 27K resistor not labeled in diag. This keeps the IRF9530 turned off when not grounded to xmit. The LT1054 has a voltage divider of two resistors to set the output to -5V. Kinda neat to have something to produce a neg supply and regulate it too. It’s good for 100mA but only 25mA is needed. The LT1085 is a 3 amp unit and if the power is applied by accident with the T/R in xmt then only 3 amps should hit the 5061 until the -5V builds up a milisecond later. It should be Fred-proof. The 5061 draws just under 2 amps regardless of B+ voltage. DEMI runs it at less then my 8.5V and they have been run as high as 10V but I don’t have the guts to run it above 9.0V.


See the “Fred-proof” comment, he must know me.  It’s a very simple design… and I posted this for the first post for a reason.  First off, Jerry WA9O and I would like to say that all of the old “you can’t do microwave if you can’t machine to the thousandth” was never correct and is even less so with our modern, internally matched, broadband components.  (Jerry has told me in the past I could forward on the design of this amplifier if I gave him credit!  I’m giving him credit!  It’s NEAT!  I will build it someday when I get off the HF “high”).

All I can say is that idea, that things had to be built to commercial tolerances to work at microwaves– did more damage to that part of the hobby than anything else possibly could have.. thanks ARRL.

It’s like (exactly) being told you can’t work DX with your HF vertical and crappy ground system, you need a 70′ tower and a beam, so don’t bother with anything less.  Well that’s nice but a lousy antenna is infinitely dB better than nothing.    In most cases, your best tolerance machine work will work on VHF+ and it will just keep getting better with experience!

In this case, that 10 GHz amp, a DBS/DSS dish and a drilled out feed or a W1GHZ horn will put you into the “big boy league” on 10 GHz for as little as $200 for the amp, nothing for the dish if you are a good dumpster diver like I am, and maybe $300-$400 for a transverter, which, of course you will build yourself, right?  And the bragging rights are always fun.. only you and the others who have done it will realize that the equipment is almost easy with modern components.  Now working DX at 10 GHz is harder but it’s a really fun challenge and there are others out there who would LOVE to help you do some.

I’d like to encourage microwaves.  And IMHO, 10 GHz is where it really becomes fun.  There are so many cool things to do on ham radio.. and this is one of the more “cutting edge” aspects of the hobby.

Probably my next post will be another “giant” post (at HF though).. but this one I am building and hopefully will test.  Check back here in a week or two for that!

73 de W0FMS


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  • Matt W1MST, Managing Editor