Go Kits

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KX3 Field Cases - July 5, 2020

I rearranged my HF go kit yet again. I sold my Yaesu FT-450D and now plan to use my Elecraft KX3 as much as possible in the field as well as at home. To maximize the usefulness of my KX3, I have put together a couple of field cases to keep everything protected during travel.

The first case has two different configurations: one using my Hardrock 50 watt amplifier, and a second with a Bioenno 6Ah lithium battery. The case is a Monoprice 22"x14"x8". After laying everything out and removing the foam to snugly fit my equipment I glued the layers together using spray adhesive and coated all the foam with two coats of Plasti-Dip. This reinforces the foam, making it much more durable and less prone to tearing and wear. The default configuration houses the KX3, PX3 panadapter, the HRD50 amplifier, and accessories (microphone, power cables, serial and RX I/Q cables). The alternate configuration swaps out the amplifier for the 6 Ah battery and a foam block to keep the battery from shifting in the case. To make use of the amplifier in the field I use my large battery box and its 40 Ah battery. In QRP mode I have a full featured low power station and enough battery power to run all day. With the amplifier the case weighs 16 lbs 10 oz, and with the battery it weighs 15 lbs 4 oz.

The second case is a more bare bones QRP setup with just the KX3, microphone, power cable, and a Bioenno 3Ah lithium battery. The case for this version is a Monoprice 13"x12"x6" and weighs 7lbs 15 oz. With this load-out I can significantly drop the size and weight of what I'm carrying while still having everything I need to setup a station other than an antenna.

Go Kit v4 - March 2, 2019

I’ve been building and rebuilding my go kit for a couple of years now and every time I do it I learn something. What I learned since I built my last version is that I really value versatility. When building a go kit you should think about what you need the kit to do and how you will be using it. The two previous versions of my kit both used rack cases to contain the radios and other equipment in one complete package. This works great for multiple reasons: it provides a lot of protection, with the covers on the cases are dust proof and water resistant, the cases are stack-able and the operator has easy access to all the radio’s ports. There are two big negatives that go along with rack cases as well: they are bulky and they add a lot of weight.

For my new go kit build I wanted to cut the bulk and weight of my kit substantially (I did some math and found that for my previous VHF case the rack case itself weighed more than the radios inside it). I also wanted to divide the kit into more versatile modules so that I only have to carry what I need in a given scenario. This is a similar idea to what I did when I rebuilt my battery box; going smaller and simpler instead of all out.

To achieve this goal I decided to use Tac-Comm tactical radio carriers. These carriers are made of aluminum, are lightweight, they stack on top of one another, tilt bales & handles are included and they offer a lot of flexibility for how you can mount equipment. On their website they emphasize the use of nylon webbing straps to secure radios, power supplies, etc. That’s fine, but I prefer to bolt things solidly in place. These carriers are not weather tight, so in the event that I need to expose them to inclement weather I will keep them inside a plastic bin to prevent equipment damage. In the end I used three carriers: two standard size (for power supply & VHF/UHF) and one large (for HF).

The power supply module uses the same Powerwerx power supply I have used on all the previous builds. It works great, is compact and doesn’t put out RFI. I mounted it in the standard carrier using the same brackets as previously and added two Anderson powerpole ports to the back of the case. It’s a very straightforward build. I thought about putting a top on the carrier, but leaving it off gives me an easy way to store the power cord and radio power jumper wires. I removed the standard tilt bale to allow for stacking on top of the larger carrier. Including cables the power supply module weighs 5.6 lbs.

The VHF/UHF module uses the same Kenwood TM-V71a and SignaLink USB combo I’ve used in the past. The radio is mounted in the carrier using the standard mobile mount. I added an ABS plastic plate in the back of the carrier to allow a place to mount a USB pass-through port and a powerpole. This provides a convenient place to hookup when in the field and gives every internal cable a place to land so nothing is loose and flopping around. The layout I chose leaves space on the side to mount the microphone inside the carrier for easy transport. Tac-Comm also sells covers to protect the front and rear of the carrier and I used a front cover with an ABS plastic extension to protect the radio’s display & knobs as well as keep the microphone cable inside the carrier. To top it off I used Tac-Comm’s steel top cover which is magnetic and allows for the use of a small mag-mount antenna for instant field deployment. The VHF/UHF module weighs 7.9 lbs.

The HF module uses the same Yaesu FT-450D transceiver I have used before, but this time I changed my digital interface. Instead of a SignaLink USB I decided to use an inexpensive USB soundcard wired directly to the radio’s data port and I key the radio via it’s serial port using rig control. I chose this soundcard because I know from previous experience that it has a low noise floor and works well for digital communications. This new arrangement saves a lot of space and allows me to reduce the carrier to its minimum height without sacrificing any functionality. The transceiver is mounted to the carrier using the same angle brackets as previous builds, only the hole placement is different. Similar to the VHF/UHF module I used another ABS plastic plate for USB & powerpole connectivity and another optional front plate for protection. I also was able to mount the microphone internally for transport. The HF module weighs 15 lbs.

The end result of all this is that I now have a very versatile and vastly lighter go kit. Since each radio and power source are separated from one another, I no longer have to carry anything I don’t need when going to the field; if I’m going to run on battery, I can leave the power supply module and vice versa. Even as a complete kit I reduced the volume of equipment by at least 50%. All together this new kit weighs 28.5 lbs, compared to 40.5 lbs for v2 and 52.25 lbs for v3, a reduction of 30% and 45% respectively. Needless to say I am very happy with the end result. Any protection I have sacrificed is more than made up for by the additional versatility and reduced weight.

Go Kit v3 - March 28, 2018

This third version of my go kit is more of a revision than a compete rebuild. After using my previous build for about a year I realized that while it is nice to have everything in one box, it is also a lot of extra weight and bulk that I don’t necessarily need. For the most part, when I operate a portable radio station I don’t use both HF and VHF/UHF, so carrying both is excessive. The solution for this is something I considered while planning my previous build, splitting the kit into a HF unit and a VHF/UHF unit.

HF Case

In order to keep this revision simple I tried to keep the shelf layouts as similar to the previous build as possible. The HF case reuses the lower shelf of my previous kit with only small modifications. The shelf was mounted in a 3 unit shallow rack case. The removal of the upper shelf from above the HF radio necessitated moving its SignaLink to the top of the power supply where it was attached using heavy duty velcro. This arrangement led me to remove the HF radio’s external speaker since there is now unobstructed space above the radio which allows for decent sound projection. The power wiring is also very simple. I kept the power supply output powerpoles as they were and added another powerpole connection for the HF transceiver. This allows for easy access to either connection. I also changed the power supply’s power cord to be removable; the previous build had it wire tied in place which turned out to be an awkward arrangement. Finally I added a new rack panel with a USB pass-through for the SignaLink. The HF case ended up weighing 29.5 lbs (including lids, microphone, and cables).

VHF/UHF Case

The VHF/UHF case reuses the top shelf from my previous build and includes several modifications. The shelf was mounted in a 2 unit shallow rack case. The biggest change was the addition of a dedicated power supply (Astron SS-12). In order to hang the power supply from the shelf I removed the top cover of the device and mounted it to the shelf using #8 hardware and fender washers. Then the power supply was reassembled. The bolt locations were chosen to avoid the internal electronics of the power supply while still distributing the weight of the device. The SignaLink and microphone connection had to be re-positioned to make room for the power supply. The separation of the radios also necessitated eliminating the powered USB hub. As in the other case the power supply output and radio power input were pulled out to the back of the case for easy interconnection. Finally I reused the rack panel from my previous build to provide access to the dual-band transceiver’s antenna and the SignaLink’s USB connection. The VHF/UHF case weighed in at 22.75 lbs (including lids, microphone, and cables).

Operation

Each case can be used by itself or as a pair. When used independently a jumper can be used to power the radio from its associated power supply, or an external power source can be used. When stacked I can use the HF case power supply or other sources (like my Power Box) to feed a RIGrunner which distributes power to both radios.

Either single case configuration results in me saving at least 10 lbs compared to my previous kit. If I do need both, the total weight is more (52.25 lbs vs 40.5 lbs), but since it is split between two cases it actually makes it easier to move. This also has the benefit of not physically tying both stations together. I can deploy somewhere and one person can operate the V/U station and another the HF and they don’t have to be sitting on top of one another. In the end I think this is a much more versatile and useful setup than my previous go kit.

Go Kit v2 - January 15, 2017

Last year I put together both VHF/UHF and HF go kits. While functional, they were very basic, and neither was as capable or robust as I ultimately wanted my go kit to be.

Design

If you look around the internet you will see a lot of people building go kits in rack cases. I always liked the sturdiness and modularity of this type of case, but not the bulk. Most builders us a full size 6 unit case, which is not compact (roughly 24″ square and 13″ tall) nor lightweight (over 18lbs). After evaluating the equipment I planned to use in the kit I realized that I did not need a full depth case. Using a shallow case saves me 8″ of depth and cuts the weight as well. I laid out several possible equipment arrangements in CAD and found that if I kept the kit fairly barebones (no SWR meters or external antenna tuners, only one external speaker) I could also move from a 6 unit case to a 4 unit and still fit everything I needed. The 4 unit shallow case I used is 22.4″ x 16.2″ x 9.1″ and weighs 12.8lbs.

The general design philosophy for this project was to have all of the equipment mounted to two shelves (one on the bottom and one at the top). After my experiments in CAD I found that a good organizational layout was achieved with the power supply, power distribution, and HF transceiver mounted on the bottom. As part of the power distribution system I wanted to incorporate an automatic backup power switch. This allows the power system to seamlessly change from AC wall/generator power to battery power. While not necessary, this is a nice feature to have because it prevents your radio from turning off while operating if there is an interruption of power (which can easily happen in emergency and field operations).

This left the VHF/UHF transceiver, speaker, and two SignaLinks for the top shelf. The SignaLinks are separated by the speaker to easily differentiate which unit is connected to which radio. I went with multiple digital interfaces because while I will most likely never be transmitting on both V/U and HF simultaneously, it can be very handy to be able to monitor both at the same time or to monitor one while transmitting on the other. Having two units also allows me to never worry about changing radio and SignaLink wiring to operate on the band I need to.

In order to simplify the cabling between the SignaLinks and my laptop I decided to us a powered USB hub and to make the USB hub accessible on the back of the case. This makes it very convenient when in the field since I don’t have to reach into the case to plug in the interface cables. The addition of a rear mounting plate gave me a place to pull out the V/U transceiver’s antenna connection for easier access as well.

I decided one external speaker would be adequate based on the layout I settled on. In this layout there is a fair amount of space below the V/U radio’s speaker to allow for sufficient sound output. The HF radio, however, has much less space above its top mounted speaker. Another consideration I made was that FM audio on V/U is generally very clean, especially compared to SSB audio on HF. Based on this I chose to use the speaker with the HF radio.

Parts

Construction

The Powerwerx power supply is perfect for go kits. It is very compact (6″ x 5″ x 2″), has convenient Anderson powerpole connections on the front (in addition to terminals on the back), and can be secured with mounting brackets.

The Yaesu 450D offers a lot of bang-for-your-buck and is relatively compact and lightweight as well (9lbs). The built-in automatic antenna tuner does not have the widest range (3:1), but I don’t plan to use it with non-resonant antennas so it should be more than adequate. Making use of the internal tuner also allowed me to eliminate an external tuner from the design, which was one of the key reasons I was able to fit everything inside a 4 unit case. The 450D was mounted using 2.5″ steel brackets along with M4 machine screws and 1/8″ nylon spacers to prevent the brackets from rubbing against the radio’s enclosure. I had originally intended to use Yaesu’s mobile mount for the 450D, however, it took up too much space and would have affected my layout. This arrangement lifts the radio about 1/2″ off of the shelf which should provide plenty of ventilation.

In the preliminary layouts I had planned to use a West Mountain Radio PWRgate and Rigrunner for backup power switching and power distribution. This plan proved impractical due to space restrictions, however, I found the perfect substitution in the Low Loss PWRgate. It is about half the size of the other backup power switch and it provides 3 output powerpoles which eliminates the need for a Rigrunner or other distribution block. While the LLPG is rated for 25 amps vs the 40 amps of the other unit, this should still be adequate for my purposes. The LLPG is very lightweight and was mounted using heavy duty double stick tape.

The Kenwood V71A was mounted using it’s mobile mounting bracket. The voltage converter for the USB hub was screwed to the shelf using its mounting tabs. The other equipment on the upper shelf was mounted using either heavy duty velcro (SignaLinks, USB hub) or double stick tape (speaker). I also added some rubber strips to the bottom of the speaker because I found in test fittings that the clearance between the speaker and the HF radio was only about 1/8″ and I didn’t want any inadvertent contact between them when the case is moved.

Cable Management

Part of eliminating the Rigrunner from my build meant that I had to provide some protection for the power wiring and radios. This was done using inline fuse holders with ATC style fuses. I also had a fair amount of radio interface and USB cables to manage. The shelves I chose are vented which makes them perfect for using wire ties to secure everything in place. I also wanted to make the go kit as straightforward as possible to assemble and disassemble. Part of this goal was limiting the wire tying of cables to individual shelves. This means that if I want to remove a shelf, I only need to disconnect the handful of cables that are connected between the two shelves (two power, one speaker audio, one SignaLink), then unscrew the shelf and pull it out. No cutting of wire ties is necessary.

I really wanted to be able to stow the radio microphones inside the go kit and I found that I could velcro the V/U radio’s mic to one of the HF radio’s mounting brackets and the microphone’s cable would then fit nicely between the power supply and HF radio. This is especially convenient since the microphone jack is in a position that makes disconnecting it a bit of a pain.

The HF radio’s mic is stowed using velcro and a strap to the inside of the front case lid. The lid has enough depth that the mic can fit without contacting the front of the power supply. The power supply AC power cord is stowed using a similar strap method as the HF mic, except it is in the rear case lid.

Weight

Part of the goal of using a smaller rack case was to cut down on weight as well as bulk. I had estimated that I could build the go kit and keep the weight around 35lbs. In the end the kit weighs 40.5lbs. I think the lesson I took from this is that wire and mounting hardware add up to more weight than you might realize.

Operation

The kit is very straightforward to setup. Once the lids are off I simply unstrap the microphones and power cord. Then I can either plug in AC power or a battery, hook up my antennas, connect USB to my laptop, and I’m on the air. I am very happy with how little bulk this kit has; with the lids removed the case is only 12″ deep and easily fits on a small table. The kit is small enough to integrate perfectly into my home station, which makes it very convenient to make sure everything is fully functional for field operations. I am very pleased with how this kit turned out and I learned a lot of along the way, especially about case layout and parts fitment.

Update – Microphone Connector (February 2017)

After using my Go Kit for a few weeks I realized that the Kenwood V71’s microphone connector was not in the best location. It is on the side of the radio and when the mic is being used it twists and otherwise stresses the microphone’s connector. To improve this situation I decided to extend the radio’s mic connection to the front of the Go Kit. I accomplished this using a 1 foot ethernet patch cable and a RJ45 Inline Coupler. The coupler was mounted on the top of the power supply with heavy duty double stick tape. This new arrangement makes the microphone connection much more accessible and greatly reduces the stress on the connectors.

Update – Integration with New Power Box (November 2017)

Part of building my new Power Box involved modifying the power circuitry for my go kit. Because the battery switching components are now off board I no longer needed the Low Loss PWRgate. In its place I installed a Powerwerx PD-4 distribution block. I also used a powerpole mounting clamp and a piece of ABS plastic to create a mount for the output of my power supply. This gives me two solid points of connection from which I can wire to my power box. Or if I am running exclusively off of the power supply I can use a simple jumper for self contained operation.

Go Kit Antennas - July 19, 2016

Mast System

My first priority was to have a good VHF/UHF antenna system. A magmount on the roof of your car is OK, but for local line-of-sight communications the gain and height of your antenna are very important. I also wanted something that I could easily transport and erect by myself.

After some investigations I decided to aim for a simple lightweight mast system that I could mount to the trailer hitch on my car. The base for this setup is a hitch mount flagpole mount. For the mast I chose the MFJ 1904H. This mast solves a lot of potential problems for a portable mast system: it is 5 feet long when collapsed making it easily transportable in my car, it is non conductive and will not interfere with any antennas mounted on it, and despite being made of fiberglass it is fairly sturdy (each tube wall is 1/8″ thick). I don’t intend to heavily load this mast so this should serve my needs well. In order to achieve a tight fit between the flagpole mount and the mast I used a section of 2″ PVC pipe as a spacer. When fully extended the top of the mast is about 21 feet high.

I also purchased a 33 foot version of this mast design from Max-Gain Systems. While this version requires some guying, the additional antenna height can greatly increase performance.

VHF/UHF

For the VHF/UHF antenna I chose the Two Way Electronix Dual Band Slim Jim. As someone who uses a J-Pole antenna as my base VHF antenna, I am very familiar with how well these antennas perform. The Slim Jim is a J-Pole made from 450 Ohm ladder line so that it can be rolled up for easy storage and transport. I mount the antenna to the mast using a nylon bolt and wingnut the passes through the insulation at the top of the antenna and a hole drilled in the top fiberglass section. This setup is very light weight and has virtually no wind loading which makes guying the mast unnecessary (under average wind conditions).

HF

For HF I did considerable research regarding what type of antenna is appropriate for emergency communications. A lot of ham radio is focused on making contacts at great distances (DX). This necessitates a low angle of radiation from the antennas being used. For a dipole this means that the antenna should be at least a half wavelength above ground. The most common HF bands used for EMCOMM are 40 & 80 meters (one half wavelength on 40 meters is about 66 feet, 132 feet for 80 meters). For EMCOMM purposes, however, we generally only need to communicate within a couple hundred mile radius of our location. This requires a Near Vertical Incident Skywave (NVIS) propagation path. It turns out that this makes our lives a lot easier since a dipole can be used for NVIS when it is mounted much lower than it would typically be. Instead of trying to get a dipole very high, mounting it at 15 to 20 feet is ideal for this application. Another benefit of this approach is that at this height the dipole loses almost all of its directionality and is essentially omnidirectional.

HF Antenna #1 – Loaded Dipole

My 80/40 Loaded Dipole was built specifically to be center supported by my 21 foot fiberglass mast. It is lightweight, only 76.5 feet long (59% of a typical 80 meter dipole), and resonant on both bands.

HF Antenna #2 – End Fed Half-Wave

Similar to the Loaded Dipole, my 80/40 End Fed Half-Wave antenna is resonant on the two most common EMCOMM bands. It is also only 76 feet long (58% of a typical 80 meter dipole) and is quick and easy to deploy in the field as a sloper when a single strong support is available.

HF Antenna #3 – Folded Skeleton Sleeve Dipole

When space and strong antenna supports are available my 75/40 meter Folded Skeleton Sleeve Dipole makes for an excellent EMCOMM antenna. It is resonant on both bands and is only 107 feet long (81% of a typical 80 meter dipole) making it somewhat more space efficient without reducing performance through the use of loading coils like my Loaded Dipole and End Fed Half-Wave.

HF Antenna #4 – Hamstick Dipoles

In an effort to maximize portability and reduce both setup time and the footprint of my antenna system I bought 80 and 40 meter versions of MFJ’s hamstick dipoles (MFJ-2240, MFJ-2275). These are heavily loaded antennas that use a base section consisting of a coil wound on a fiberglass rod with a stainless steel whip on the top. While a small loaded antenna will not have the efficiency or the bandwidth of a full size antenna, it is considerably smaller (15 foot span). The dipoles are lightweight and my fiberglass mast seems plenty strong enough to support them.

Performance (updated February 2017)

I have done 24 hour WSPR tests of both the Loaded Dipole and End Fed Half-Wave antennas and they perform similarly, which is to say they are quite effective antennas. I used the End Fed Half-Wave during Winter Field Day and was able to easily make contacts on both 40 and 80 meters using both SSB and PSK31.

To test the Folded Skeleton Sleeve Dipole my Ham Radio club used it during Field Day 2016 and made over 350 contacts. They even loaded it up on bands other than 80 and 40 meters and it performed well. I would say this is definitely the best antenna of the four, however, it is also the largest and heaviest.

I have yet to do much with the Hamstick Dipoles, but I plan to do some testing in the future.