portable 140 / 440 mhz field radio box (revised)

© 2016, G. K. Lee. All rights reserved.

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Grassroots Emergency Communications Operations

Portable 140 / 440 MHz Field Radio Box (Revised)

© 2016, G. K. Lee (KI6GIG). All rights reserved.

http://www.neighborhoodlink.com/RTC-TH_Tech/pages Email: [email protected]

You may post questions / comments about this paper to the Discussion are of our website.

The portable field radio box enables radio operations away from our base station. This includes conducting field testing of radios, antennas, as well as supporting ARRL Field Day and other local ham radio demonstrations. Most demonstration activities would end before battery recharging is actually necessary. GECO portable operations the radio use battery power. Solar recharging of the battery is the preferred sustainable option to demonstrate extended field operation capabilities (especially for emergency situations). The radio is a QYT KT8900 Dual Band (144/440 MHz). Echolink demonstrations can be conducted by connecting to the GECO Echolink node 584695 at 439.640 MHz (if in simplex range of our base station). It would be necessary to coordinate with other radio operators to connect to the same Echolink node from their stations to facilitate the Echolink demonstration. Other uses for this portable unit: Away from vehicle mobile unit

Use this radio when more transmission power needed than available with the HTs (handi-

talkies).

Readily transported or configured for backpack operations

Can be mounted for bicycle mobile

Emergency radio communications

The guidelines used to design this field radio box included:

Self-contained

Compactness Ruggedness

Water and dust proof EM shielding

We used a surplus .50 caliber ammo can for the project box. When closed, it is sealed against water,

dust, and the all metal body is a Faraday cage to protect the equipment from EMP effects.

http://www.neighborhoodlink.com/RTC-TH_Tech/pages

mailto:[email protected]

Portable 144/440 MHz Field Radio Box Grassroots Emergency Communications Operations


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GECO Portable Field Radio Box Schema The main components of the radio box are the QYT KT8900 dual band radio, the sealed lead acid 12 VDC, 7.2 AH batter, a cooling fan, the

solar panel charge controller with 3, 6, 12 VDC sockets and a usb charging port.

Optional equipment that can be used with the radio box include a 150 w solar

panel, a 12 VDC/AC inverter.

The GECO 2m/440 MHz field radio box:

Radio: 2m/440 MHz

Cooling fan

Battery (12 vdc 7.2 AH)

Solar Panel Charge controller (w/ 3, 6, 12 vdc socket, usb sockets)

Optional items used with the field radio box:

Solar PV panel

Optional 12 VDC/AC inverter

12 vdc lights

External bank (1 or 2 12 vdc 16 AH batteries)

Deltran battery charger (if line power available) Solid green outlines indicate item is on-hand and installed in the current version of the radio box. Dashed green

outline = items are on hand but do not fit in the radio box. We have yet to acquire the solar PV panel.

Step 1: First in are the Solar Charge controller and sealed lead acid battery. Attached cables for the

Solar panel and battery are placed for easy access and fitted with Anderson PowerPole connectors.

Step 2: The QYT KT8900 dual band radio (with an extra cooling fan) is attached to the side of the can using Velcro so it can be used in or out of the can. Fused power cord plugs into the 12 VDC accessory socket.

There is ample space for a rolled up J-pole or Slim Jim antenna and some coax. This means the complete radio system fits in the box and can be protected from adverse EMP conditions. We used Anderson PowerPole connectors to maintain interoperability with our other radio gear and accessories. The permits mixing and matching radio and power supplies between our base and vehicle / bicycle / pedestrian radio operating systems. This improves the resilience for our emergency communications operations which is a fundamental guiding principle for GECO (Grassroots Emergency Communications Operations).



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Specifically, the power cord from the Solar Charge Controller to the battery has ring terminals on the posts of the charge controller and Anderson PowerPole connections on the end going to the battery. There is another short lead on the battery with Anderson PowerPole connectors. When running on the battery in the box, the battery lead connects to the solar charge controller. If solar recharging isn’t available, Anderson PowerPole jumper leads from the battery charger can connect to the battery jumper.

Step 3: If needed, the 12 VDC/AC inverter can be stowed inside the box.

Step 4: There is space for the microphone and a rolled up J-pole or Slim Jim antenna.

We installed a small 12 VC cooling fan on top of the QYT KT8900 under the mounting bracket. Zip ties allow the fan to be adjustable to center it over the radio’s housing/heat sink We left the bracket in place as an extension of the heat sink. It also serves as a fan guard.

The fan power cord connects to the radio power cord. The radio would only be connected to power when it would be used. The fan runs whenever the radio is connected to power.

In cold field conditions, the radio is unlikely to overheat. In warmer conditions, the plan is to remove the radio from the box for better air circulation and cooling.



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The currently available antenna for use with this radio box is a Nagoya UT-108UV (mini mag mount dual band 15.6" whip high gain VHF/UHF (144/430 MHz). It is too long to fit in the radio box. It will be stowed externally, making it vulnerable to EMP effects. [Note: To mitigate this potential issue, we plan to get a roll-up J-pole or Slim Jim antenna to stow in the radio box

A PL-259 to SMA-Male coax adapter is

needed to use the Nagoya UT-108UV

mini-magmount dual band whip antenna

with the QYT-KT8900 radio.

Selections for all field radios is largely driven by the GECO base station operating frequencies. Since our field radio operations range from vehicle, bicycle, pedestrian mobile and field portable modes, appropriate antennas will be acquired that fit the relevant mode/parameters for compactness and transportability. With interoperability between operating modes as a priority, various adapters / connectors must also be included in the inventory. At this time, the radios in the GECO inventory have either SO-239 or SMA-male fittings. The table below shows the current GECO antenna inventory. Common range antenna coax connectors include PL-259, SO-239, and SMA-female. The GECO field antenna inventory will expand over time.

Radio / Frequency - Power / Ops Mode*

Antenna Fitting

on Radio

Nagoya UT-108UV

Comet SSB220

HH-9000 Dual Band

Beam JTD1

Discone SMA-f PL-259 PL-259 SO-239 SO-239

144/440 MHz

144/220/440 MHz

10,6 m/144, 440 MHz

144/440 MHz

25-1300 MHz

Bao Feng F8HP 144/440 MHz; 8W / 5W / 1W

VM, BM, PM, FP SMA-m

No adapter needed

Mount with SO-239 and coax with SMA-f.

Need coax with PL-259 /SMA-f Bao Feng UV-82X

144/220 MHz; 5W / 1W VM, BM, PM, FP

QTY KT8900 144/440 MHz; VHF 25/19W; UHF 20/10W

BM, PM, FP

SO-239 Need coax with SMA-m/ PL-259

Mount with SO-239 and coax with PL-259

Need coax with PL-259 / PL-259

TYT TH9800 2m/6m/144/440 MHz

29/50/144 MHz 50W/20W/10W/5W 440 MHz 40W/20W/10W/5W

BS, FP

TYT TH9800D 2m/6m/144/220/440 MHz

29/50/144 MHz 50W/20W/10W/5W 220/440 MHz 40W/20W/10W/5W

BS, VM, FP

*Operating mode codes: BS = Base Station, VM = Vehicle Mobile, BM = Bicycle Mobile, PM = Pedestrian Mobile, FP = Field Portable. Bold face indications primary GECO use; Italic type = preferred secondary use.

Optional Equipment 1. 12 VDC/AC Inverter: If there is a need to run 110 VAC equipment in the field (e.g. laptop

computer), we have a small unit available that fits in this radio box. The Recoton has a max power output of 220W. We added a cooling fan to the inverter. The power for the fan is wired to the 12 VDC automotive accessory plug. When the unit is plugged in, the fan runs. In cold field conditions, this unit is unlikely to overheat. In warmer conditions, the plan is to remove the inverter from the box for better air circulation and cooling.



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Zip ties hold the fan in place using wooden chopsticks as spacers and fan mount bracket. The power leads for the fan were wired directly to the 12 VDC accessorty plug. The 20 inch power cord is sufficient to allow removing the inverter from the radio box while plugged into the

socket. The inverter can be more likely be used with a larger field battery bank than the single battery in the radio box. Use with the radio box battery is deemed as an extreme emergency situation.

2. 12 VDC Lights: The two lights are part of the Solar Charge Controller set. They use two dedicated 12 VDC phono plug sockets on the Controller front panel. They each have a 12.5 foot cord with an inline switch. These are sufficient to illuminate our field station. The 5W 12 VDC bulbs draw 380 mA. In the future, we may replace these with LEDs to minimize power consumption. An alternative is to run the lights from a larger external battery pack. [Note: The lights are packed into a separate weatherized storage box. They do not fit into the radio box.]

3. 150 Watt Solar PV Panel (future buy): The future plan is to add a 150 W solar panel to this equipment set. Solar battery charging adds to the resilience and sustainability of the portable field radio box. Anderson PowerPole connectors will be used on the cords of the panel. This increases the flexibility and interoperability of the Solar Charging system to any and all small-sized GECO battery / battery bank system.

portable 140 / 440 mhz field radio box (revised)

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