How Long Can One Operate on Emergency Power

I have seen many a set-up in YouTube and other SHTF Preparedness web sites of amateur radio gear, with go boxes, batteries, solar power backup, but I have seen very little of what I think is a well thought out set-up which addresses maximum utilization of meager energy resources should such a situation arise.  For example, I have seen go boxes which employ high current draw rigs – even on receive.  For an objective look at the comparison between various rigs, I have collected data over the years on how HF and VHF radios consume  power on receive and transmit. Based  on this data, one can put together a set of expectations on how long such a set-up will be operable on back-up or emergency power.

Several variable are at play
Receive current draw – the amount of current a system consumes in amperes or milliamperes while just listening
Transmit current draw – the amount of current a system consumes in amperes or milliamperes while transmitting – key down carrier
Duty cycle – the percentage of time the mode is in full key-down (100% duty)

Let us consider some common modes of transmission
SSB – 25% Duty Cycle (Source QST)
CW – 33% Duty Cycle (Source QST)
PSK31 – 100% Duty Cycle
RTTY – 100% Duty Cycle

What one needs is an instrument that measures current draw during receive only and during key-down (100% duty cycle).  I have put together operating time expectations using a 14 ampere-hour depletion to 50% capacity – the maximum depletion one would want to push a deep cycle battery to without severely affecting longevity of the battery.

As one can plainly see, operation at 20 watts greatly reduces the operating time.  Not all rig / amplifier combinations are ideal.  Some are quite power hogs.  The most miserly of the transceivers are also amongst the most limited in terms of operating mode - but the rigs can practically operate "forever" with solar power.  For example, the Elecraft KX1 only consumes 55 milliamps on receive and less than 1 amp on TX.   It is a CW only rig and the version I had was a 4 bander 10,20,30 and 40m.  There are now several of this type of radio on the market.   This will just about double the operating time at 30% duty cycle to 11 hours.  The most versatile ones are the Elecraft K2, KX3, and Yaesu FT817.  The power output on the latter is limited to 5 watts.  Operation of the Elecraft rigs greater than 10W will require an external amplifier.  External amplifiers for QRP radios are manufactured by several sources and can be purchased as kits,

Elecraft KXPA100 and KPA100 (K2 only)

Juma PA100 

Ten Tec Model 418

HFPacker

Worked Country #243 Ghana 9G5ZZ

These days new countries are hard to come by and new ones are always cause for excitement.  No LOTW here so will have to send away for this one

#231DXCC Clipperton Island Confirmed

The last one  took a while..... the QSO was in March of 2013 and only confirmed just now.  It was no fault of the DX.  I had the wrong QSO information in my log.

#231 TX5K Clipperton Island LOTW
#230 FT5ZM Amsterdam Island LOTW
#229 TJ3SN Cameroon LOTW
#228 3C0BYP Annobon Islands CARD
#227 VQ9JC Chagos Islands LOTW
#226 A65CA United Arab Emirates - LOTW
#225 8R1Z Guyana CARD
#224 VK9MT Mellish Reef LOTW
#223 S9TF Sao Tome and Principe Island LOTW
#222 T8CW Palau Card
#221 PY0F/PP1CZ Fernando de Noronha Card
#220 5Z4T Kenya  Card
#219 DU3/N0QM Philippines LOTW
#218 T77C San Marino LOTW
#217 3A2MW Monaco LOTW
#216 HS0ZKX Thailand LOTW
#215 J28NC Djibouti Card
#214 VR2UW Hong Kong Card
#213 TZ6BB Mali LOTW
#212 EX2B Kryzgystan  Card
#211 4S7VG Sri Lanka Card
#210 C31CT Andorra Card
#209 UN7QX Kazakhstan Card
#208 3V8BB Tunisia LOTW
#207 JD1BHA Ogasawara LOTW
#206 V73MW Marshall Islands LOTW
#205 JT1CS  Mongolia LOTW
#204 TO7CC Reunion Island LOTW

Surprise Visit from M1GRY and G7FBD

A special thanks to Mat G7FBD and Gary M1GRY who dropped by on their way from Atlanta to Dayton.  They're taking the opportunity to see more of the U.S. and several members gave them pointers on seeing the mountains and driving a bit of the Blue Ridge Parkway before making their way to Dayton late on Wednesday.  They joined a good group of members for pizza and beverages at Wild Aces after the meeting.

DXCC #230 FT5ZM Amsterdam Island Confirmed

Got notice at the club meeting fromW4FC Paul Greaves that FT5ZM uploaded their logs to LOTW

New Look for the Shack

The shack now incorporates the SCRaGGs concept.  The heart of the system is the StationPro2 which controls the RF switching between rigs.  The antennas are connected by a 3 position antenna switch.  Not seen is the Drake L4B underneath the desk along with its power supply.

SCRaGGs Project - Self Contained Radio Grab and Go System

• Have you ever wanted to have a radio system that will stay on in the event of a power outage? And can operate for long periods on standby or emergency power?
• Have you ever wanted a radio system that seamlessly transfers power from commercial mains to backup power?
• Have you ever wanted a radio system where you have the means to recharge the backup system using either generator or photovoltaic  system?
• Have you ever wanted to have a radio that you can deploy for field day or an ARES deployment without needing to assemble all the needed gear?
• Have you ever wanted a radio system that can provide total RFI shielding  in the event of EMP burst or very strong RF fields?

If the answer to all of the above is “YES” then welcome the SCRaGGs concept (Self Contained Radio Grab and Go System) where backup power, power switching, charging system, power distribution, antenna tuner, transmitter and receiver are all contained in a durable & portable case.

Ready to Go - All Components Inside

In the Operating Position

Backside showing openings and SO239

The back of the unit now shows to HF bulkhead SO239 connectors and an opening for the power supply AC cord.   The power supply is a Gamma Research HPS-1A which weighs only 1.5 lb and is only slightly bigger than a cigarette pack.  The Low Loss Powergate by KI0BK (a device is used to seamlessly transfer power from commercial mains to back-up or battery power without interrupting the transmission.  The solar charge controller (also by KI0BK) takes care of any external charging of the battery using solar panels.  All of the above items are all contained within the unit.  The ultimate in integration is achieved by using the KXPA100 amplifier shown in the photo below.  The RF shielding is provided by an aluminum foil wrapper behind a thin liner that is tacked on within the enclosure.

KX3/PX3/KXPA100 Combination

SCRaGGs with a K2

The SCRaGGs system can be ordered from jacalawoodworks.com.