My Kraken Installation... Let's Go!

When I took delivery of my Land Rover Discovery mid COVID era,  I thought I looked at every "radio hobbyist" related important thing to help in antenna, power cable and radio placement. One thing I overlooked was that this vehicle had an aluminum roof.

If I ever wanted to use magnet mount antenna this would not be good. I was also not planning to drill holes in the roof like in my last vehicle. After experimenting with hood and lip NMO mounts for VHF/UHF communications it was clear that performance from all locations was not as good as I had wanted, so I needed to try something different on this vehicle since I like omni directional patterns as much as possible.

After changing out the OEM roof rails for aftermarket ones plus getting some higher cross pieces with T slot centers,  this opened up more antenna options after a tip from a local ham about using carriage bolts instead of over price T-slot posts to help mount things. Thanks Jim! 

Now. before I get to the Kraken,  just to explain the vehicle roof further in the photo above, the rear most cross bar antenna mount I fabricated from  1 1/2 steel stock drilled out to accept 2 NMO mounts plus one 3/8 24 thread mount for different antenna needs.  This mount was then elevated using 1/2 inch spacers to give clearance for the underside of the mount and the coaxial cables.  This should be visible towards the rear of the Kraken array. 

The antenna shown is a 17 inch dual band NMO whip that is the perfect height for garage parking.  The high radiation take off angle works well in the Hudson Valley known for its geographic features which make for challenging communications at times.  

When I go on longer trips I add on a much taller tri band 144/220/440 whip and then run the 17 inch whip for an auxiliary radio.  My mount rail has proven to give me much flexibility while at the same time being low profile to the general public.

As example, I can screw on a ham stick for HF operation or use a 70 inch whip with a tie down while mobile for HF via an antenna tuner and balun. This antenna mount bar was a quick project and has proven to work well.

Currently my daily driver radio is the Yaesu FTM-300 for VHF/UHF plus Civ/Mil air band monitoring while in motion.  For HF, I sometimes use the Icom IC-705 or Xeigu G90. Perhaps a Yaesu FT-891 may find a home in the car eventually, we shall see.

Now to the Kraken!

You came here based on the photo right?  When it came time to figure out how to use the Kraken in this vehicle on a "when needed basis" , I used the same type of steel stock from my antenna mount for the five Kraken antenna arms and I came up with the perfect removable mount for it in the process.

Parts Required

One 3/4 inch flange mount has a pair of 1/4 inch spacers which some carriage bolts pass through along with two washers.  One wing nut on each bolts allows me to tighten the mount to the roof quickly and easy via the T-slot. It is easy to unlock my cross bar, loosen the wing nuts and slide the mount in or out.

The spacers were needed so I could pass the five coaxial cables through a 3/4 inch diameter coupling which connect the two flange mounts together.  This allows the coax to pass through the bottom and up to the top to each antenna arm easily.

The actual "list" of materials for those that like it that way is as follows:

• 2 - 3/4 Inch Flange Mount Pipe Fittings
• 1 -  3/4 Inch threaded black steel MPT Nipple - 1 Inch length
• 3 - 1 1/2 Inch wide plain steel. Each is 48 inch and cut down as needed
• 10 - Matching #10-32 3/4 Inch screws and matching steel nylon lock nuts
• 1 - 1/4 Inch 3/4 Inch carriage bolt and matching lock washer and nut
• 2 - 1/2 Inch Carriage bolts, washers and wing nuts.
• 1 - Package of 50 reusable velcro ties. (HD Item # 90924HD/202261940)

Assembly should be easy to visualize. I did not make plans for legality reasons as I can not control how well people can build things strapped to a roof and potentially driving at highway speeds. All hardware can be found at most any decent or general hardware retailer.

Testing in phases

Driving around with just this center mount with no antenna arms for about a week whistled a little while in motion so a velcro wrap is put around the two spacers to deflect the wind. This cleaned up the whistle between the roof rail and the antenna hub mount and its near silent. The coax fed through the NPT nipple is not affected with the velcro 

Each of the antenna arms made from 40 inches each of 1 1/2 steel was needed to space the antennae out in a pentagram for frequencies as low as 120 MHz.   Some velcro wire ties are used to keep the cables from flopping around in the wind.   

Each antenna is magnetic and easily stays attached on the arms at highway speeds. No whistling is heard so the aerodynamics must be pretty good.  Each end of the antenna arms were rounded off and both edges sanded down prior to painting in flat black paint to create better aesthetics. 

Antenna arm zero faces directly ahead with element one being to its approximate 2 O'clock position and the opposite side at about 10 O'clock is element four.   These three elements are each held in place with a pair of machine bolts secured with nylon insert lock nuts.  This makes for quick disassembly or maintenance as needed.

The rear two most elements roughly at the 4 O'clock and 7 O'clock positions are  cold welded together along with a short cross piece of steal stock that has a single carriage bolt and nut to hold it down with some precision against the other antenna arms.   Removing this single bolt allows for smaller storage space when the system is not on place and the front three elements stay in place.

Each of the coax lines have thoughtful cable markers on them to make it easy to known which coax goes to which receiver port on the Kraken.

I added some marker points on each antenna arm at key frequency ranges to aid in changing use cases such as for 2m Fox Hunts and other RDF related interests across the VHF and UHF spectrum.

A few more velcro ties secure the five cable bundle to the cross rail and then are all carefully pulled flat against each other before closing the car door so as to not pinch the thin coax.

With each of the five coax connected to the right ports, the only other connections to the Kraken are minimal.  If you wish to learn more about the Kraken SDR,  please use Google. This is just about my implementation and not a review.

The "Non-Antenna" Stuff. 

A nice orange hard case from you know where was pressed into use to keep the Kraken safe but I am still deciding how to make it a permanent home inside.

The red colored 1 foot length USB-C cable is used for data transfer and is connected between the Raspberry Pi 4B and the Kraken.   Both the Kraken and RPI4 have grey USB-C USB cables for power only and plug in to a USB power hub which offers the 2.5A amps needed per device.  

The power hub also has the ability to be powered from a range of 8-20 Volts which is nice to provide the 5V and 2.5A needed to each of the devices. Two ports on the USB power hub are not used.   This is the power hub used if you are interested on Amazon. https://www.amazon.com/dp/B08MCZNYZN 

Finally, the USB power hub which originally came with alligator clips were removed and replaced with power pole connectors as shown.  An easy and useful upgrade for USB power!!

Shown in the photo is a Westinghouse power station which supplies 12V power to the USB hub but is easily changed to other power sources such as vehicle power or some other battery if desired. I like using the power station since it can monitor current draw and wattage.

During use, the Kraken plus Raspberry Pi seem to draw an average of about 10W which is not too bad.  With intermittent use for a whole day plus forgetting to turn it off overnight, the power station still was at 40% capacity.

The photo of the Raspberry Pi,  Kraken and USB power hub and its minimal cables should be easy to understand.  The row of blue lights on the Kraken show each receiver is in use and the five coaxial cables lead out the window topside.

So how does the Kraken work?

A few comments to share is that the Kraken is sensitive. Do not transmit near to it. For a recent Fox Hunt where we used 146.565 MHz as the target frequency, I used the Yaesu FTM-300 on low power only on a local UHF repeater.  I did not see to have any issues but was still careful to not overload the Kraken while doing RDF.

The antenna elements were all extended for about five hours and driving for about two of those.  Everything held up just fine.

I paired the Kraken/RPI4 to my mobile phone using the Android App, but also monitored the spectrum and DOA via the web server on an iPad Mini. This worked out well but even though the Raspberry Pi 4B is overclocked, I really need to upgrade to a Raspberry Pi 5 when it is reasonable.

Some experimentation with the ability to track more than one signal on the same frequency was interesting. I tried it with two after making the adjustment in settings.  Technically up to six signals can be tracked but I was not able to try that.

After a few earlier uses of the Kraken on my past vehicle, everything worked well at the 20.7db gain setting for VHF.   Using this new mount, I found overload easily and backed the gain down to below 10db.  

During our fox hunt, we had three search areas each 3 by 4 miles. I started out as a hider in the lower quad listed in FN31bp.  Driving up to where the "Charlie" fox was in FN31bs, the turn by turn directions after getting a fix roughly a mile away was fun.  However, this fox was hidden in a cemetery and I had to use normal eyeball navigation to reach my destination. Pretty much everyone was impressed with this setup and how fast I got to the fox. 

Also worth mentioning that the 17 inch VHF/UHF NMO whip did not seem to affect the Kraken array pattern which was a major added bonus!

During the hunt, I was also tracking the western fox via a different bearing the whole time which was cool to see on the map as I drove north.

I can not say enough great things about the Kraken. It is expensive, but it paid for itself well before this fox hunt via other missions where I needed to find transmission sources. My favorite test location was a local aviation VOR since it was ground level.   During that test I even used a separate SDR running with SDRangel to track its bearing, but that is best left for a different article.

Hope you enjoyed this overview and no, I do not plan to share my dimensions used in my build since you can use the calculator and details found in Kraken Forum where I drew inspiration from.  All I can say that the materials for my mount ended up costing around $100 in total and that does not include brainstorming and fabrication time.

If I had to build this again, I would make a few changes but nothing major as this has proven to be really nice so far for me.

Why United States amateur radio can not evolve?

 

The title of this post sounds a little like a "Jeopardy" answer in the category of "Famous son inventors".  Probably, the question was "Beyond silencers, this son of a different American pioneer was also known for the growth of which hobby, which involves shooting things other than bullets into the air?"

1ZT: Getting your attention!

Its always easy to poke fun at the love of all things high frequency and possibly even one of the important founders of the Amateur Radio Relay League (ARRL) who we have to credit, much like the National Rifle Association (NRA), for embedding certain hobbies and perceptions into the DNA of Americans.  

This is none other than the old man himself, Hiram Percy Maxim, who is not only one of the co-founders of the ARRL, but also one of the early inventors of the firearm silencer and son of the mastermind behind the Maxim machine gun.

Did you know there was a more legitimate co-founder of the ARRL named Clarence Tuska?  He was also the person behind the much loved QST magazine and likely would be more apt to read an article like this compared to Mr. Maxim.  

Both of these "OM" helped evolve the world of wireless communications for hobbyists like us, but we are now at a time where we need to prevent us from facing extinction.

As an engineer,  Mr. Tuska is who promoted the use of the higher 200m and above spectrum rather then the lower 600m band and was much more focused as an experimenter with radio technology.  I like Mr. Tuska and what he did for the hobby in the United States, thanks to his awareness to share information in written form. Lets now jump into something fresh and new! 

Why?

I write this after sharing notice of an important evolution within radio technology which has not yet really come into wide spread use across amateur radio yet.  

Today, we can not wait around for QST to learn about the latest innovations.  Its right here in the digital domain is where you will learn about something new. And, by the time most people get QST in the mail, its out of date and more time is spent trying to find who to give it to! 

The Future.....

What I am talking about is known as a software definable front end preselector.  Those I shared this latest Crowd Supply project with immediately needed to point out that something like this is useless, since it does not include capability for our much beloved "HF" spectrum allocations.  

At $419 USD, it is expected to cover spectrum much lower in order to appeal to the amateur radio hobbyist to make it a worth while purchase.

This preselector is a versatile, highly useful tool for providing programmable bandpass filtering for a software-defined radio, among other applications. 

In the receive path, that filtering can be used to mitigate the effect of strong blocking signals; in the transmit path, it can be used to help reduce out-of-band radiation. 

ATEK1001 aims to provide an affordable filter bank for radio enthusiasts and SDR users. More of the technical specifications concerning the 485MHz to 7.7 GHz can be read about here. 

Starting so high into UHF spectrum even limits its applications for most of the amateur radio community members interested in bands such as 70cm, 1.25m, 2m, 4m, 6m and of course the rest of the HF band.

What makes the ATEK101 interesting is how small it is. 

Who cares. More money for another HF CW/DIGI Kit!!

For those interested in Software Defined Radio (SDR), this is where the market software defined radio front end (SDRFE) is really targeted.  Not the HF only operator who only chases CW contacts in South Dakota.

The popular Lime SDR and Lime SDR Mini are joined by a branded product also available via Crowd Supply called the Lime RFE which does cover the important spectrum we care about and is only a mere $699 USD and covers up to 3.5 GHz plus all the important amateur radio bands in between. 

It is however a much larger product. There is even a $549 USD option for those who do not need the cellular filtering and this will appeal more to frugal amateur radio operators looking for something new. 

If you wanted to experiment with RF filtering, the Lime RFE or the ATAK1001 are what is available today.   

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SIDE NOTE:   Interested SDR for HF?   Get online for the QDX available October 11th at 2:00 PM EST until units sell out.   https://qrp-labs.com/qdx.html 

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Do I need a SDR Front End?

Reason here is to illustrate there are some interesting things taking place within the world of software "re-defined" radio worth keeping an eye on, but another area is the niche that the phase coherent software defined radio is filling.

We are jumping to a totally different topics here because I can not find anything about a dedicated HF only or even HF and VHF RFE to write about, but now I know I have your attention.  

A phase coherent SDR is a combination of multiple software defined radios which can act together or separate from each other to do interesting things.

Combining multiple receivers can act as a way to filter or combine signals and the RTL-SDR.com provided "Kerberos" product was the first low cost way to do this with its four receivers which are identical in performance to the popular RTL-SDR V3 most who are reading this probably own already.

Software for Software Defined Radio

A challenge when the Kerberos first came to market in early 2019 was little available software to use it with and it also needed a little more horse power from a computer to utilize its capabilities.

Things changed for Kerberos when the Raspberry Pi 4 became available and it was far easier to use the Kerberos for applications like radio direction finding or using its phase coherence capability. 

Software also improved since 2019, with applications like SDRangel being one of the first to offer easy to use multiple receivers at the same time in a visual application.   

Using something like a Kerberos and its 4 separate receivers capable to tune to any approximate 2.4 MHz chunk of spectrum at one time means you can monitor multiple bands at the same time or even the same frequency via different receivers and find ways to optimize reception by using different DSP filtering tools.  

By the time many people got excited about the capability of the Kerberos, it was already out of production or sold at lower cost, but there is a new model called the Kraken about to be unleashed which will include five independent receivers.  so,  its time to jump onboard now if you want to do amazing things with a phase coherent receiver. 

There is a more polished software program specific for the Kraken, which can also be used with the Kerberos if you have.  

Many more traditional SDR programs like those which Rick W1RHS let us know about recently also exist now which can be used with phase coherent hardware.

During the October 19th session of the popular Northstar Digital Net managed by Jim WA2UMP,  some discussion about both phase coherent receivers and possibly other SDR topics like RFE will be mentioned. 

Steve K2GOG of HVDN will be available to share more details and field questions on some other aspects about software defined radio that hopefully, will make the likes of Mr. Tuska and Mr. Maxim proud. 

Please be sure to join us Tuesday October 19th at 8:00 PM Eastern Time on Brandmeister Talk Group 31630 if you are interested in topics like this on the evolution of amateur radio by using the future to do so thanks to DMR.