Boafeng UV5R USB Soundcard Interface

I recently purchased a Baofeng UV5R5 to throw in my Go Kit as a backup handheld and I decided to build an interface to be able to send and receive digital signals. The interface was intended to be as simple and inexpensive as possible, much like the radio itself.

VHF/UHF digital EMCOMM transmissions in my area typically use the MT63 mode which is very robust and can work quite well using only acoustical coupling. While this technique works surprisingly well, it has limitations. If the area you are operating in is too noisy, your audio is too weak, etc. the data transmission can have issues getting through correctly. It also doesn’t work very well for modes other than MT63.

USB soundcard interfaces are very common, I have multiple SignaLink USBs myself, but they are definitely overkill for this application. After some experimentation, I built this simple interface for under $20.

Parts

Construction

The main idea for this project was to replace the external speaker microphone functionality with that of the USB soundcard. In order to do this I used the speaker mic cable and wired it to two 3.5mm stereo audio cables such that the speaker output from the radio connects to the microphone input of the soundcard and vice versa. Each splice was soldered and insulated with heat-shrink tubing. The entire joint between the three cables was then secured with more heat-shrink tubing. Each 3.5mm plug was marked with colored electrical tape to make it easy identify which cable plugs into which port of the soundcard (red for microphone, green for speaker).

Operation

To operate, I plug simply plug in the cables and connect the USB soundcard to my computer (a big advantage of this model of soundcard is that it does not require special drivers for Windows 10 or Linux, it is truly a plug-and-play device). When I am ready to send data I simply key the radio using the PTT switch on the side and click the transmit button in the digital software. When the transmission is finished I unkey the radio. I had originally played around with an external VOX circuit as well as the UV5R’s internal VOX feature, however, neither of them would reliably key the radio and stay keyed throughout an entire data transmission and I decided they were unnecessary. Using manual keying is actually somewhat of an advantage since it simplifies the interface, reduces complexity, and doesn’t require changing the radio’s configuration.

Calibration

I used FLDIGI to test the interface over simplex to another radio. After some experimentation I found that with the radio’s speaker volume set at a comfortable level (about 1/4 turn) a setting of 50% for the soundcard’s microphone gain was a good audio level for receiving data. For transmitting, I found that a setting of 1% from the soundcard’s speaker produced the cleanest output.

If I was going to build more of these I think I would add a 10K ohm resistor at the connection between the soundcard’s speaker output and the radio’s microphone input. This would attenuate the signal somewhat and allow for finer control over the transmit audio level. Even so, as it stands now the audio is clean and data transmission worked flawlessly. I have used this interface on my local digital net and it performs very well. This has definitely found a place in my Go Kit.

Ham Radio EMCOMM Go Kit – Version 2

Last year I put together both VHF/UHF and HF go kits. While functional, neither of these was as capable or robust as I ultimately wanted my go kit to be. My new goal was to build an all-in-one station in a box that was not overly bulky or heavy.

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.

QRP Go Kit

After assembling a solid set of QRP gear this year I wanted to put everything into an easy to transport package. To house and protect the kit I used a Monoprice 13″ x 12″ x 6″ Weatherproof Hard Case. This case is the perfect size to fit my mcHF transceiver, and Elecraft T1 autotuner, along with a 3″ external speaker, hand microphone, and power cable. All together the case and equipment weigh a little under 7.5lbs.

With this kit, all I need is 12VDC power and an antenna and I am on-the-air. This should pair perfectly with a small battery and either my random wire or end fed half wave antennas that I built recently.

Elecraft T1 QRP Autotuner Kit

img_0841In the months since I completed my mcHF SDR transceiver kit, I have thought about building a QRP antenna tuner to go along with it. After some investigating I came across the Elecraft T1 which is available assembled or as a kit and can handle 10W of continuous power. While I have never owned any Elecraft gear, they have a very good reputation and several people in my ham radio club swear by their equipment. The kit looked like a fun project and a perfect match for my QRP gear so I decided to order one.

img_0842The kit took about a 4.5 hours to complete. The included instructions are very detailed and do a good job of emphasizing critical parts of the build. The biggest issues arise in regard to several components that need to be mounted in a very specific way in order for the case to fit properly. The circuit boards are fairly tightly packed, but anyone with good soldering experience should have no problem assembling this kit.

img_0844img_0843The finished product is very compact and incredibly simple to operate. I really appreciate that the instructions are printed on the front label in case you forget. So far I have used it to tune a couple different antennas of various designs and it performs very well. It finds matches quickly and the relays aren’t annoyingly loud like some autotuners. I look forward to getting a lot of use out of this and my mcHF.

Manual Antenna Tuner

Manual Tuner (10)Manual Tuner (9) Automatic antenna tuners are incredibly convenient devices. They also require power, interface cables, and many have a limited impedance matching range. Manual tuners, on the other hand, feature a simple design and can have a very wide matching range.

Manual Tuner (6)Manual Tuner (4)After deciding that I wanted to build a T-match type of tuner, I needed to find some high voltage air variable capacitors. I looked around at what was available and found this great pre-made assembly that features two 22-360pF variable capacitors (rated for 1kV) and a 12 position rotary switch (rated for 5A). This should be able to handle 100W when properly matched. After deciding on this component I selected an 8″ x 6″ x 3.5″ aluminum enclosure for the tuner.

Manual Tuner (2)The next part of the tuner is the inductor. In order to make use of the 12 position rotary switch I needed to make a coil with taps. I also had to keep the coil relatively small so that it would fit in the enclosure I was using. After doing some research I found that an inductance of 30-40uH is typical for a T match antenna tuner and should be able to match a good range of impedances from 160M – 10M. K7MEM has a great single layer air core inductor calculator that uses common PVC pipe as a coil form. For the coil I decided to use 18AWG teflon insulated wire since it should be large enough to handle 100W and the teflon insulation is both easy to work with and very heat resistant. Using the calculator I found that 46 turns of wire on a 1.25 inch PVC pipe resulted in a 35uH inductor that would fit nicely in the enclosure.

Manual Tuner (5)To wind the coil I used a ring terminal to secure the starting end and started winding. At every tap point I separated the insulation and soldered a jumper to the exposed wire. Then I continued winding until the next tap point and so on until I finished the coil with another ring terminal. I tapped the coil at turns 2, 4, 6, 8, 12, 16, 20, 24, 30, 36, and 42. The finished coil was then bolted on top of nylon spacers to the enclosure.

Manual Tuner (3)Manual Tuner (1)To finish the tuner I wired the taps in the order they were wound to the rotary switch. The start of the coil should be wired to the point where the variable capacitor rotors are connected together. The end of the coil should be grounded to the enclosure along with the common point on the rotary switch. Each variable capacitor stator is wired directly to the center of a SO-239 connector, one to the input and one to the output of the tuner. Finally, I added a ground stud to the enclosure.

Manual Tuner (8)Manual Tuner (7)When using a tuner of this design it is good to keep in mind that the most efficient match occurs when the capacitance is at a maximum and the inductance is at a minimum. Therefore when adjusting the tuner I always start with the capacitors at close to their maximum setting (fully meshed) and the inductor on the first tap. I then click through the inductor taps until I see a dip on the SWR meter and adjust the capacitors to achieve the lowest SWR I can.

I have used this tuner with a couple different antenna designs and it performs fairly well. When used with various dipoles and other wire antennas I have been able to achieve matches the majority of the time. However, I may need to adjust the design of the coil since it seems that I never make use of the later taps and may not require such a large coil.

Ham Radio EMCOMM Go Kit – HF

HF Kit (1)After some thought I decided that I wanted to treat this as more of a HF Field Kit than a true Go Kit. I had heard good things about the Yaesu FT-450D and after seeing sale prices and mail-in rebates drop the price to $600 I decided to buy one. The Yaesu (9”W x 3.3”H x 8.5”D, 8.8 lbs) is not as compact as some HF rigs, but it is nowhere near as unwieldy as my Kenwood TS-590SG  (10.6″W × 3.8″H × 11.5″D, 16.3 lbs) which serves as my main HF transceiver in my station. For such a compact radio it contains many comparable features to my larger and considerably more expensive Kenwood.

Features

The Yaesu 450D is an entry level transceiver, however, it includes a lot of features that give you considerable bang for your buck.

  • HF/6M Coverage
  • 100W Transmitter
  • IF DSP Filtering (Width, Shift, Contour, Notch, Noise Reduction, etc.)
  • Backlit Buttons (perfect for field use at night)
  • Voice Keyer (perfect for contesting and Field Day)
  • Built-in Antenna Tuner

Field Case

HF Kit (2)To house the Yaesu I used a Monoprice 22″ x 14″ x 8″ Weatherproof Hard Case. This should keep the radio, SignaLink, and microphone secure. Less damage prone items like the power cable can be transported in my backpack. For additional capability I decided to add a second case to the kit.

Accessory Case

This case is the same model used to house the Yaesu 450D. In this case it contains my Manual Antenna Tuner, a MFJ 4125P 22A switching power supply, and a MFJ 822 cross-needle SWR Meter. This case greatly expands the capabilities of my HF kit. The manual tuner has a much wider tuning range than the autotuner inside the 450D, the switching power supply allows me to power the radio from line or generator power if available, and the small SWR meter is perfect for station monitoring in the field.

When line or generator power is not available I will rely on my Go Kit Battery Box. I think that this setup will prove to be versatile and the Yaesu 450D provides many modern conveniences as well as 100W output in a compact package.

mcHF SDR Transceiver Kit

A huge part of the history of ham radio involves people building their own equipment. In fact that is how things started since at the beginnings of radio no commercial hardware was available. Over the years various companies and organizations have sold transceiver kits, but in recent years most of these have consisted of basic morse code only or single frequency single side band devices intended for digital communications. With the increased development of software defined radio (SDR), however, this is changing. Earlier this year I came across the mcHF SDR transceiver project and decided to purchase one of the kits. Unlike other basic transceiver kits the mcHF is a full featured radio with 80M-10M coverage, multi-mode support, variable bandwidth filtering, DSP (noise reduction, notch filtering, etc.), sound card interface, rig control, and band scope / waterfall capability. Not bad for a $388 kit.

mcHF (1)mcHF (2)The project was originated by Chris, M0NKA in the UK about 2 years ago and the design has gone through a number of revisions resulting in the current v0.5, which is what I purchased. One of the major reasons I was willing to undertake this project was that the kit offered by Chris includes the circuit boards already populated with about 95% of the surface-mount parts, including all of the tricky to solder chips and super tiny resistors and capacitors. The only remaining parts to install are larger, and therefore easier to solder, surface-mount parts and standard through-hole components. The builder also has to hand wind several toroid inductors and transformers. You also have to provide your own final power amplifier MOSFETs, shielding plate between the boards, and case for the radio. These requirements go along with the way this kit is sold, which is to say bare bones. The kit includes zero instructions. The builder is responsible for sorting through the mcHF downloads page, the mcHF Yahoo group, and the Github Wiki to find the details regarding how to wind the toroids and transformers as well as details on any recommended mods and instructions for how to use the radio.

Since this project is open source, both the hardware and firmware have undergone considerable development. In fact, from the time I started building the board to when when I completed the project a large firmware update was released which revised the main screen and menu layout as well as added a number of fixes and features, including the ability to control the transceiver via the USB port and detect the transceiver as a sound card device with a PC.

mcHF (3)The mcHF consists of two circuit boards called the UI board and the RF board. I built the UI board first, and then built the power supply section of the RF board so that I could power up and test the UI board. Chris has a very helpful document on the mcHF webpage that steps through the process of installing the bootloader and uploading firmware to the CPU on the UI board. So after only about 4 hours of work I had a functional UI board.

mcHF (7)Next I completed the remainder of the RF board, which was fairly time consuming since winding toroids and transformers is a tedious operation. Documentation exists for how to wind the transformers, however, the only information regarding the toroids is on the RF board schematic which details how many windings each core requires. Extra attention should be paid to stripping the enamel wire used for the toroids and transformers. Even though I diligently sanded off the outer coating and thought that I had solid solder connections to the board, I did not do a good enough job on two of the toroids which prevented the radio’s operation on the 80M band. After desoldering and re-sanding the wires I achieved a good electrical connection and consequently 80M functionality.

mcHF (10)mcHF (11)This portion of kit construction is somewhat confusing because there are a ton of possible mods for the various transformers that can improve performance of the final power amplifier. I decided to build mine in the default configuration which results in a solid 5W output on 80M-12M and about 4W on 10M. When modified, users report 10 or more watts of power output. The only modification I made was with regard to the SWR bridge where RG-178 coax is used in place of a single winding of enamel wire. Construction details for many of these mods are available in a document on the Yahoo group produced by Clint, KA7OEI who has done considerable work on both the hardware and software of the mcHF.

Although not technically a mod, I did add a resistor that is regarded as “optional” on the UI board schematic. This resistor provides power for when an electret microphone is used. Since I would be modifying an Icom HM-36 I had lying around to work with the mcHF, I needed to install this resistor in order for the microphone to function. For this I used a standard 1/4W resistor since I had on of the correct value in my junk box and just soldered it to the surface mount pads. In order to avoid shorting with nearby components I carefully shaped the resistor’s leads and used electrical tape to insulate between the parts.

mcHF (5)mcHF (6)After completing construction of the boards, I turned my attention to completing the radio as a whole. The first step of this was to construct the shield plate between the boards. For this I used a thin mcHF (12)sheet of aluminum that I hand cut, drilled and nibbled according to a pattern available on the mcHF website. I then test fit and assembled the board and shield sandwich to check for proper clearance. When I was satisfied I completed the assembly using 5mm standoffs.

mcHF (19)mcHF (17)If you look around the web you will see a lot of people who have built the mcHF using the same case. This case is sold by Artur, SP3OSJ from Poland for about $63. If you email him at asnieg@epf.pl he will give you the details for how to order. The case comes with all of the knobs and buttons as well as a small piece of acrylic to protect the LCD display. The front panel is pre-machined, however, the endplates are left to the builder to complete. I also had to file some of the button holes to allow smooth operation and I had to sand the acrylic to fit the opening in the case.

mcHF (8)mcHF (9)Since the case serves as the heatsink for the power supply circuitry as well as the final amplifier transistors, a good mechanical connection between the components and the case is necessary. To mcHF (13)mcHF (14)accomplish this I soldered brass #4-40 nuts to the heatsink fin on power supply and amplifier components. I then drilled holes in the case to match where these nuts line up when the case is mcHF (15)assembled. When bolts are inserted and tightened, the electrical components are pulled tight to the wall of the case. In order to achieve a properly aligned connection, I had to grind away a small amount of material where the final amp transistors contact the case (note the hole I drilled in the wrong location due to my inability to follow the old rule of measure twice drill once). The last step in construction was labeling the buttons and ports, which I did using vinyl self-adhesive labels and my laser printer.

The final adjustment before testing the transmitter involves setting the proper bias for the final amplifier and then setting the transmitter gain for each band of operation. Documentation for these adjustments is on the Github Wiki. Basically you set the bias in one of the mcHF’s menu settings while keying the transmitter with no audio present as you watch the current draw of the radio. The transmitter gain is also a menu setting. These adjustments can be accomplished with an ammeter and a RF power meter.

mcHF (16)Finally, after about 20 hours of work I put my mcHF on the air. After adjusting my microphone gain I made a contact on 40M SSB. I then plugged the transceiver into my PC and fired up WJST-X. Following the guide on the Github Wiki I was able to get rig control working and made a half dozen contacts using JT65 on the 30M band using nothing but the mcHF and my laptop. The next day I checked into my local 10M SSB net and received good signal and audio reports from the other regulars who are familiar with my voice.

Overall I have to say that I am incredibly happy with the mcHF kit. It has been a great learning experience and the radio itself is an incredibly capable and configurable device that offers a lot of bang for your buck. I plan to use the mcHF quite a bit in the future and look forward to any future firmware updates. I also hope that this kit leads to other similar kits in the future that can help get more hams back to building equipment.

I highly recommend this kit for anyone with some electronics experience. While the documentation has not been collected into one easily digestible package, the kit itself is actually very straightforward to put together and I was able to get it on the air with only a cheap multi-meter and an RF power meter. It is also an incredible bargain for such full featured radio; I spent under $500 total for the kit, case and other ancillary parts (not including the microphone) which is not bad at all when you compare this to what is available commercially.

Update – New Knobs, Bootloader & Firmware (August, 2016)

After using the mcHF for a few months I decided to look for some new knobs since the smaller ones included with the case I purchased aren’t ideal. I found some on Mouser that come in various colors and are designed to work with the “D” shaped shafts of the mcHF’s encoders. They have a nice soft rubber feel and the colors help to differentiate which knob is which. Each knob cost under $1, so this was a very economical upgrade.

Recently Andreas DF8OE, who is the main developer for the mcHF, released version 2.0 of the mcHF bootloader. The updated bootloader allows the use of the larger USB Type A port for firmware upgrades using only a USB Flash Drive. This eliminates the need for the proprietary software that was required to update the firmware in the past and solidifies the open source development of the mcHF going forward.

Andreas also released version 1.2 of the firmware for the mcHF. The new firmware has a number of feature improvements and bug fixes including better spectrum display performance and system responsiveness overall. Other future upgrades are in the works and I look forward to what the new features will bring.

Update – Serial EEPROM (November, 2016)

While checking some of the posts on the mcHF Yahoo Group, I came across one from Andreas that emphasized the importance of installing the optional EEPROM. If the EEPROM is not installed the radio saves settings to the CPU’s FLASH memory whenever the radio is turned off. All of this memory writing adds up and can lead to failure of the FLASH memory. Since I don’t want to worry about replacing the CPU in the future I ordered the recommended EEPROM (24LC1026) chip and installed it on the UI board. I also installed the required 0.1uF capacitor using the smallest through-hole component I could find. Upon booting up the transceiver the EEPROM was detected by the firmware and the radio seems to be working perfectly. This was an easy and worthwhile upgrade, especially since the EEPROM only costs about $3.50 and should protect the FLASH memory from being worn out in the future.

Update – New Tuning Knob (November, 2016)

After some extensive searching I finally found the perfect tuning knob for the mcHF. OKW makes a very nice line of knobs, part of which is a series designed for communications gear. To match my mcHF’s black enclosure I bought the A3140069 which is 40mm in diameter and mounts to the encoder’s 6mm shaft using a compression collet. This knob can take two different styles of cover (with or without finger dimple) in an assortment of colors. I went with the A3240109 cover which features a finger dimple for faster tuning. This is a huge upgrade over the tuning knob provided with my case and really improves both the looks and functionality of the mcHF. Not bad for under $5.

Ham Radio EMCOMM Go Kit – VHF/UHF

VHF Go Kit (7)Recently myself and others in my ham radio club have been getting more involved in emergency communications (EMCOMM) training and activities. As part of this effort to be better prepared for emergencies I decided to build a go kit or “station in a box” that could be used as a portable communications system.

VHF Go Kit (2)VHF Go Kit (1)Since VHF and UHF are the most used bands for EMCOMM I started with that. I already had a Kenwood TM-V71a dual band (2 Meter and 70cm) transceiver which is an ideal radio for this application. At full power it can output 50 watts and unlike many transceivers of this kind it features a data port on the back for easy connection to an external sound card (I use the SignaLink USB) for digital communications. It also has a detachable faceplate which allows for a lot of flexibility regarding where and how the transceiver body is mounted.

To house the electronics I chose the Monoprice 14″ x 16″ x 8″ weatherproof hard case which is similar to Pelican cases at a fraction of the price.

VHF Go Kit (4)VHF Go Kit (3)For power, I chose to include a 10 amp switching power supply in the go kit. I used the Astron SS-12 since its dimensions were such that it fit perfectly in the case when mounted next to the transceiver. In case 120V is not available, I can simply unplug the transceiver’s powerpole connection from the power supply and plug it into my battery box.

In order to mount all of the equipment in the case I built a base of 1/2″ plywood. The base consists of a single sheet cut to fit in the case glued on top of a four 1/2″ spacer blocks which raise the sheet above the bottom of the case. This serves two purposes:  first it negates the need to round the bottom edges of the sheet to match the curve of the case and second it doubles the thickness of wood that the mounting screws have to grip when screwed in through the bottom of the case. An added bonus of raising the sheet is that it provides space to store excess cable from the faceplate separation kit in an out of the way location.

VHF Go Kit (6)VHF Go Kit (9)Mounting the transceiver to the plywood is done using the mobile mounting bracket for the radio. The power supply is mounted by removing the rubber feet from the bottom of the power supply and replacing them with spacers and screws for a strong connection to the plywood. The microphone mount is also simply screwed to the plywood. The faceplate is mounted to the lid of the case using the separation kit mount which uses very strong double stick tape. The SignaLink is mounted to the top of the power supply using industrial strength velcro which allows for easy removal of the unit if I want to use it in a different configuration while holding it very secure when I want to leave it in the case.

VHF Go Kit (5)Before I mounted anything to the plywood I applied a coat of clear polyurethane. This not only makes the oak veneer look a lot better, it also seals the wood and provides some protection. The equipment was then mounted to the board and it was mounted in the case using 4 wood screws driven through the bottom of the case. In order to help restore the weatherproofing of the case I used silicone caulking to seal around the screw heads.

Overall I am very pleased with how this go kit turned out. To get on the air all I have to do is open the case, hook up power (either 120V or 12V), hook up the coax to the antenna and plug in the USB cable to my laptop if I need to run digital. In all it’s a very capable VHF/UHF station that weighs about 17 lbs and isn’t much bigger than a shoe box.