Trish's FT-817 QRP Page


Portable and Emergency Power Considerations for the FT-817

Beginning a discussion of the FT-817's power consumption and requirements for portable and emergency power use let's start out by quoting the FT-817ND's specifications as listed in the manual for reference.  For the sake of all of my discussions please assume the unit requires a negative ground and the stock MH-31 microphone is used.  Also a W4RT SSB filter is installed as well as a Hear-It DSP by W4RT Electronics.

If you are using this discussion to compare the FT-817ND to the Elecraft KX3 please remember to keep it fair. The KX3 can output a max of 10 watts and the FT-817ND a max of 5 watts.

The antenna was connected to a dummy load.  Non-squelched volume level set to 50% on internal speaker.  We chose 3.97Mhz as our test frequency as we most often operate voice in that area.  We chose PKT as the operating mode to represent maximum modulation.  The DSP is removed from the circuit for these tests. For reference it adds 30-40mA to the below values when enabled.

Yaesu Quoted Power Requirements
Normal Supply Voltage: 13.8 VDC
Operating Voltage: 8.0 to 16.0 VDC

Receive Current: 450mA
Receive Current Squelched: 250mA
Transmit Current: 2000mA (2 Amps)

Our Observations
Running from an external 13.4v LiFePO4 battery on 3.97Mhz PKT with back light and LED's enabled.
Receive Current: 350mA
Receive Current Squelched: 340mA
5w Transmit Current: 1790mA
2.5w Transmit Current: 1380mA
1.0w Transmit Current: 1040mA
0.5w Transmit Current: 889mA

Running from an external 13.4v LiFePO4 battery on 3.97Mhz Data with back light and LED's disabled.
Receive Current: 350mA
Receive Current Squelched: 307mA
5w Transmit Current: 1760mA
2.5w Transmit Current: 1350mA
1.0w Transmit Current: 1008mA
0.5w Transmit Current: 850mA

Running from an external 13.4v LiFePO4 battery on 52.525Mhz FM with back light and LED's disabled.
Receive Current: 360mA
Receive Current Squelched: 310mA
5w Transmit Current: 1700mA
2.5w Transmit Current: 1350mA
1.0w Transmit Current: 1029mA
0.5w Transmit Current: 890mA

Powered Down
Idle Current: 15.4mA

Now with all that said its pretty plain to see that the 817 requires a fairly substantial amount of current for a QRP rig, especially when compared to some of the typical home brew QRP rigs or Elecraft's K2 but one should keep in mind that this is a commercially designed rig that is microprocessor controlled  and covers from 160m thru 70cm (more or less) in all modes where a homebrew CW only radio can get by drawing significantly less current with out all the extra bells and whistles..

Internal Batteries
If you are planning to use your FT-817 in portable mode (hiking, biking, camping, etc...) We would highly recommend dumping the Yaesu supplied internal battery no matter if you own an original FT-817 or the FT-817ND as at best the factory supplied battery is only 1700mAh and there are significantly higher capacity batteries available that are completely compatible with the internal charging circuit. 

The most basic way to improve your internal battery capacity is to use the supplied "AA" battery holder with 2300mAh to 2700mAh AA cell NiMH batteries that are currently available.  If you wish to charge these cells with the radios' internal charger you will need to disconnect the battery trays green wire. (Warning, do not attempt to charge non-rechargeable batteries in the tray.  With the green wire disconnected the radio will try to charge any cell installed in the tray if you turn the charge timer on.)  The problem with using the internal charger to charge any battery is that it only supplies a few milliamps of current.  The supplied NiMH 9.6v 1400mAh pack requires 8 hours to charge, a 2300mAh pack requires two 8 hour cycles for a total of 16 hours.  Here's the problem with the internal charger, 16 hours of charge time for 3 to 4 hours of runtime, a terrible tradeoff in my opinion... 

The other option to charge when using the "AA" battery tray is to use one of the many 1-2 hour individual cell quick chargers that are available at most department and hardware stores.  The down fall of this approach is that you end up frequently opening the battery cover (which is somewhat difficult to operate).  Also you should be aware that wires and connectors for the battery tray are quite frail/delicate and could easily break or wear out with frequent swapping of the internal battery or cells.

The other option for the internal battery is to buy an after market battery pack which is the option we chose after quite a lot of deliberation.  Of the different after market packs available we decided on W4RT's "One-Plug Power" 9.6v 2500mAh NiMH battery pack for its' self resetting fuse, thermal and over current protection, external charging option, and the fact that it disconnects itself from the radio when the external quick charge jack is used.  We are quite capable of making our own battery packs and have made several external ones for for use with our 817 but in the interest of saving time and the fact that W4RT's battery pack is very reasonably priced (as compared to ordering all of the parts and making our own) we found it couldn't be beat. 

In the beginning we have been running the W4RT battery pack through multiple charge/discharge cycles using our radios internal charger to condition the cells but ultimately the 16 hours it takes to charge the pack is just to impractical.  Now W4RT does sell their "One Fast Charger" that connects to the packs external charging jack which will charge the pack in ~2 hours but the thing looks like a clumsy multiple piece hunk'o'junk (sorry W4RT, we like many of your products but this one just seems sub-standard) which would not lend itself easy to travel with, even more limiting is the price and the fact that it requires AC power to charge with.

After doing some research we discovered Maxims' MAX712 charge control IC chip on Maxims' website at Reviewing their white papers they even supply the perfect circuit/schematic to deploy it.  The thing that makes this option the one for us is that we are addicted to solar energy and solar panels for all of our amateur radio work and we can design this circuit to run off of the 12-16VDC that my solar panels typically supply so we can not only continue to keep our hobby independent from the grid but can charge our batteries anywhere we might be as long we have a partly sunny day or the 13.8v supplied by most cars these days.

External Power
The FT-817 is much more flexible when it comes to external power sources as can run on anything from 8 to 16VDC as long as it can supply a minimum of 500mA current (Note:  At 500mA external supply current we recommend having an internal battery installed if you are planning to transmit as the radio will fall back to the internal battery if it needs more than 500mA such as when transmitting)

Our 817 follows us around most of the time running off of one of our 13.4v LiFePO4 batteries which we charge with a pair of 28w of solar panels, by the time one is run down (about two days of monitoring with about 30 min talk time per day) the next has been recharged (even on cloudy days).   We also have a 300w solar panel array residing on our roof which is connected full time to our ham shack and base equipment.  The 10w portable cell is enough to run the radio in receive mode but does not supply enough current for transmit but it does a nice job of trickle charging our 13.4v LiFePO4 batteries or the internal batteries.  The 10w panel supplies about 560mA in full sun.  The 300w array on our roof can supply ~18A and is enough to run our entire station, even in full 100w transmit mode (Note: We use a solar charge controller to limit the arrays voltage, without the controller the array can supply as much as 21VDC under low/no load conditions which would most likely fry our favorite radio.)