The Short Vertical Antenna by Jerry Sevick, W2FMI(SK)

A very short antenna had about the same power gain and radiation pattern as a full half-wave antenna.

“My first interest in the short vertical antenna began when my thesis advisor at Harvard, Professor R.W.P. King, developed the full theory of the short antenna. In it he disclosed that a very short antenna had about the same power gain and radiation pattern as a full half-wave antenna. The main difference was that the resistive component, the radiation resistance, was very small in comparison. In turn, the short antenna has a very high capacitive reactance, which has to be cancelled by various loading techniques.

The theoretical results show that the power gain (when compared to an isotropic radiator) for a very short antenna, even one that is less than 1 foot high on 40 meters, is 1.5. This increases slowly to 1.513 for an 11-foot vertical. These gains are to be compared to about 1.62 for a resonant 1/4-wave vertical. This difference amounts to less than 0.4 dB or 0.07 S unit, based on 6 dB per S unit.

Base loading,[ as shown in Figure 2-3 above ], yields the lowest value. Top hat loading yielded the largest value of radiation resistance for a particular height. A top hat is also considered the most low-Q loading element. The reduction in height due to top hat loading (with a conducting wire around the perimeter) is approximately equal to twice the diameter of the top hat. A four-spoked wheel approximates, to a good degree, a solid disk. Doubling to eight spokes only improves the loading by about 9 per cent. Thus, a few radials on the top of a vertical, which are electrically connected by a perimeter conductor, are very effective.

The data were obtained by essentially cancelling out the reactance and measuring the resistive value with a simple impedance bridge. Because I used an extensive ground system together with base loading coils with Qs approaching 900, the resistance measured was actually that of the antenna itself. At the radial point the input resistance approaches the theoretical value of 35 ohms which strongly indicates low earth loss and reliable data.”

Summarized from a book by Dr. Jerry Sevick, The Short Vertical Antenna and Ground Radial, CQ Communications, 2003.

Fact checking Dr. Sevick there is a book published by ARRL written by Robert J. Zavrel, Jr. called Antenna Physics: An Introduction. From pp B.2: “A short vertical’s value will be about 6 ohms for a 1/8 wave physical height. For a perfectly top loaded 1/8 wave vertical, value becomes about 24 ohms…a fourfold increase in radiation resistance when compared to an unloaded simple vertical of the same physical height” These values agree very closely with those in Figure 2-3 above.

The above excerpts have been field tested in a 160 meter vertical antenna constructed in 2018. This vertical has been very successful and is still in use today. It has eight radials, each 100 ft long made of 4-ft wide welded wire fencing laid flat on the ground. The vertical element is made of 43 ft tall aluminum tubing tapered to average 1.5 inches in diameter. The top hat is made up from 6 102″ CB whip antennas with hookup wire connecting the tips.

Inside the box is a matching coil which is tapped with a coax feedline at the 50 ohm point. This setup is good up to about 300 watts. It needs to be hardened before it will get up the legal limit.

1.5 KW Amplifier Off Grid

Running a full kilowatt from battery power has it’s challenges. This note steps through the design and installation of the amplifier, inverter, battery bank, and solar panels. First, the amplifier. It is a Flexradio 4O3A PGXL. To reach 1500 Watts output it requires 220 Volts AC. It does not run on DC. Here it is waiting for some AC while sitting next to the Flexradio 6600 exciter .

The next item is the inverter which provides the AC. A Victron Energy model Phoenix Inverter Smart 24/3000 has been chosen. It provides 3000 watts at 230 volts when connected to a 24 volt battery. This inverter was chosen because it has RFI certification, a reputation for meeting specifications, and it was less expensive than some others.

Next component is the 24 volt battery bank. LiFePO4 lithium ion batteries were chosen, of course. The capacity of each cell is 180 AH. Sixteen cells are connected in parallel/series to provide 24 volts DC with a capacity of 360 AH. Aren’t they pretty?

Finally, the solar panels. This array is four 100 watt panels wired in series/parallel to provide enough voltage and current to charge the batteries.

It really works! This is the control panel on the amplifier. Notice the output power is shown in the upper left corner, 1512 watts. Id is the current on the drains of the LDMOS finals, 43 amps. It is also nice to notice that under the load of a full kilowatt the inverter is holding the AC at 228 volts. With no load the voltage is 230 volts which means only a 2 volt drop at full output.

A clamp-on ammeter on one lead of the AC shows 9.3 amps of current.

One concern during the design phase was whether the AC connector on the amplifier was heavy enough. It is only a type C13 which is a 10 amp connector. Today’s measurement of 9.3 amps and the fact that the connector stayed perfectly cool to the touch is reassuring.

Next a look at some of the “glue” holding the stages together. The batteries are protected by a BMS. BMS stands for Battery Management System. It’s the big red thing. It will cut off the power if the voltage is too low or too high and it will try to keep the cells balanced. Electrically it goes between the negative terminal of the battery and the negative lead to the inverter. One small red wire goes to each cell to keep track of the state of the cell.

To the left of the BMS is the shunt resistor for a Victron battery monitor. A battery monitor is not required but makes it easy to keep track of the battery’s state-of-charge remotely. The black thing in the upper left corner is a terminal block. A copper strap connects between the terminal block and the shunt resistor. These items together make up the negative leg of the circuit.

In the positive leg there is only one component. That is a 250 amp fuse. Victron specified big 1/0 cable for the inverter DC power, and specified the 250 amp fuse.

One other piece of glue is the AC circuit breaker. A GFCI breaker is connected between the inverter and the amplifier to protect the inverter from overload and to protect humans from electrocution. It is 16 amp 240 volts. Don’t hunt for this unit in the 2020 NEC code. It is not a product designed for the U.S. market. It is designed for the 230 volt standard in Asia and Europe. This project is using European standards rather than U.S. The main difference is this is not “split phase” as in the U.S. which means there is no third wire on the 220 volt circuit. Why is it done this way? Because with the U.S “split phase” wiring a second inverter would be required to get the third wire, approximately doubling the cost. There is no safety or any other reason not to use the European standard. This system is entirely off grid and therefore NEC code is not required. Safety is a big concern and all European standards have been adhered to for safety.

Some observations

Sizing and the capacity of the components is a big part of any design. Today’s numbers provide some insight. The amplifier was drawing 9.3 amps AC at 228 volts. That’s 2120 watts (watts instead of VA because power factor is assumed to be 1 due to automatic PF correction, so watts and VA are equal). The amplifier was producing 1514 rf watts which is an efficiency of 71%. This calculates to 92 amps DC from the batteries (unfortunately no dc reading was taken). Looking next at state-of-charge (SOC), good practice for LifePO4 batteries is to limit depletion to 20 per cent SOC. That is, operate with SOC between 20% and 90% which provides 70% of rated capacity. Usable capacity would therefore be .70 X 360 AH or 252 AH ( or 6678 watts at 26.5 volts). Under a constant load of 92 amps the batteries would be expected to last 2.7 hours. With a 50 per cent duty cycle mode like FT8 the batteries should run at least 5 hours. There are no plans to operate at 1500 watts on FT8. This is just a worse case example.

Concerns would include whether the 4-panel solar array (400 watts) is adequate to maintain this large battery. That would not be the best way to look at it. Consider instead whether the array is adequate to provide typical amplifier operation. If the amplifier is operated two hours a day at 50 per cent duty cycle that would use 92 amps ( or 2438 watts at 26.5 volts). The panels generate about 2 kw on a good day (400 watts X 5 hours of sunshine). That is close to the 2.438 kw of typical usage. Good to go. On cloudy days the batteries are oversized so they will have capacity to operate for more than one day without sunshine. Winter is close and some hard numbers will soon be available. If needed the existing PWM charge controller could be replaced with a MPPT controller for 30 per cent more output. After a few weeks of operation in November the batteries have recharged to 90% every day when there was sunshine. As of late December during the solstice all is still functioning well.

A lot of effort and expense went into this project but it is proving that running a kilowatt from batteries off the grid is possible.

November 22, 2020 – The amplifier has a problem. It is refusing to transmit on all bands except 160 and only puts out 500 watts on 160. This problem started after receiving a message that SWR was too high and the amp should be shut down. The amp was quickly shutdown but has not worked correctly since. It was connected to the A3S antenna on either 15 or 17 meters when the failure occurred. Possibly the amp was putting out too much power for the A3S and a trap shorted out. Apparently the amp’s protection circuits failed. A ticket has been opened with Flexradio but Covid and Thanksgiving have delayed the response.

December 12, 2020 – Amplifier is fixed and back in the shack. Flexradio’s warranty tech support is amazing. They requested a remote test and determined from the results that it needed new finals. The amp was shipped to Austin, repaired at no charge, and shipped back in two weeks time. What a quick turnaround. Kudos to Flexradio.

The finals are MRF1K50H LDMOS transistors each rated at 1.5 kW dissipation. Mouser has these listed for $900 each in single quantities.

Update – June, 2021: The amplifier system made it through the entire winter without any power problems and all worked as designed. To avoid destroying any more final transistors FRStack3 was installed. FRStack reduces the exciters output power when an amplifier is placed in operate mode, protecting the finals. It is performing that function well. Lesson learned.

Baby Solar Panel

A baby solar panel was added for the purpose of charging the battery dedicated to LifePo4 heating.

The panel is only 10 watts and will probably not do the job but it was available and worth a try. Heating the LifePo4 batteries is done to allow more hours of charging and discharging during the winter. LifePo4 can only be charged when the temperature is above freezing. Discharging is ok but the battery is more efficient if it is warmer than 0 degrees Celsius. They are already protected from charging below freezing by the solar controller. Heaters just add some hours of operation in the Colorado winter that otherwise would not be available. A separate third battery is being used for the heaters. Experience last winter showed without heaters the batteries do not get warm enough to take a charge until little or no daylight is left.

Update: A 100 watt panel has replaced the baby and has been added to the end of the rack. A thermostat is on each heater but keeping the heat on 24 hours a day is too much drain on the heater battery. The 20 watt heaters draw 25 amps at 13 volts or 325 watts. There are 16 heaters deployed between the cells. Each heater is placed between two cells. Currently the heaters are on a relay that is controlled remotely to turn on the heaters when they are needed and to save battery capacity.


Adding a Web Controlled Rotator to A3S

Project 7 of 7 for October, 2020 – projects to keep sane during Covid-19 Lockdown

Status: All work is completed.

A new Yaesu G-450ADC rotator was ordered from GigaParts. Still needed are the rotor plate, the cable, and the interface to make it remote controlled. Cable and interface are on order from DXEngineering and HRO. This project has hit a snag. Rotor plate is special order and has a November ship date. It has not even been ordered and by the time it gets here the weather could be too wintry to install it.

Universal Towers saved the day. An order was placed directly with them today and they promised a much earlier delivery date.

“The rest of the story” is this tower is decrepit. It was used 10 years to hold up wireless Internet antennas on a windy hill. It has two blow outs from being overloaded. Even though the blowouts have been repaired the concern now is it might not be able to keep the A3S in the air. Torque is the tower killer when wind makes a beam twist. An overloaded tower can fail from that twisting motion. When this tower is down for the rotor installation a torque arm will be attached in an attempt to reduce the twisting motion.

Remote Controlling The Rotator

All parts have arrived. The Yeasu G-450 rotator is the new DC version which makes absolutely no detectable difference in the operation but it makes lightning protection easier. Relays had to be used on the AC rotator because the AC voltage was too high for the 26vac/31vdc MOV’s on hand. Perfect for the 20 volts DC the new version uses. Modifying the controller for access over the Internet looks like this:

Actually the controller is not modified. A few wires are tacked onto existing terminals inside. Wires are brought out through an existing hole. The controller could be easily restored to original. In the picture above, the green thing at the bottom is the remote interface from model RCU-1216:

The interface talks to the RemoteRig 1216H Webswitch and will get mounted inside the controller. A Webswitch already exists at the remote site to provide remote access of the first rotator on the taller tower. That missed getting written up. That’s why this is being written up now. The unit has the capability of two rotators so all that was needed was this interface to the Webswitch. The installation just needs some hookup wire and a solder iron.

There is no brake release button on Yaesu control boxes so a brake release connection is not needed. Only the Pot potentiometer connection and the two motor activation buttons are needed. A data pair and a power pair connect back to the Webswitch.

For this rotator the two jumpers, P5 and P6, are opened up to accomodate the voltage on the Yaesu rotator for direction indication potentiometer. Voltage maxes at 1.3 volts on the pot. Next attach a little Blue Tack or 3M gray stickem to hold the interface in place.

Stick it to the inside of the cabinet and you’re done. It should look something like this:

Coming out of an existing hole in the back are two pairs of wires. One is for 12 volts DC. The other is the 1-wire data pair (1-wire really means 1-wire and ground). Next step is to install and test at the site.

Today the rotor plate was mounted and the rotator is mounted to the plate. A short piece of aluminum tubing was cut to go from the rotator to the mast. A hole was drilled for a bolt to keep the mast from twisting and slipping.

The tower was raised a few feet to see if it is too heavy with the rotator. It is noticeably heavier and harder to lift but not impossible. None of the gin components complained. The rotator only weighs 7 pounds and the wire is probably 2 more pounds. Another 9 pounds is apparently not overdoing it. Next the cables will be extended where needed for slack and they will be dressed. The bolt will be installed. The rotator connector will have a waterproof boot installed. The balun will be reworked to provide enough slack for turning the antenna (the balun is near the center of the picture with cable ties holding it to the tower leg). The rotator cable will be run through the cable entrance at the shed and MOV lightning protection will be provided. Inside the shed the controller will be connected to the RemoteRig Webswitch and all will be tested. It will be really nice to be able to turn this beam in the direction of the signals as they change.

Today, the balun was rebuilt by replacing the RG-58 windings with LMR-400. It is still 5 turns through a stack of 4 Mix 52 ferrite toroid cores. It looks like it can handle a lot more power now. Only the common mode current is flowing through the toroid.

Proving the balun is working is a matter of observing the signal pattern on pskreporter. In this case it is a nice flashlight beam shape in Europe indicating the balun is doing it’s job. It’s job is to keep common mode currents from generating stray radiation which distorts the pattern. No pattern distortion, the balun is working.

The rotator mounting is completed and the cables are dressed. Ready to raise the tower.

Back up in the air the rotator turns the beam perfectly with no issues. As for remote control, a relay is being used to switch between the two rotators. The other rotor turns the 203BA 20 meter beam on the big tower. One rotor at a time is accessible over the Internet.

This project is completed.

160 Meters 4 Square Receive Antenna

Project 6 of 7 for October, 2020 – projects to keep sane during Covid-19 Lockdown

Status: Completed

For the virtual Dayton Hamvention this year Contest University had some wonderful online presentations. One was especially interesting to someone who still has countries needed on 160, W3LPL –  “Effective Low Band Receiving Antennas”. A video is still available on YouTube. Frank Donovan, W3LPL, listed receive antennas from the smallest to the largest along with ranking their effectiveness. The best of size, cost, and effectiveness looks like the 4 square high impedance active antenna. DXEngineering offers one in a bundle with all possible parts needed, DXE-RFS-SYS-4S. One is on order.

In Frank’s excellent presentation only one antenna performs better and that is twice as big and only has 1.5 dB Receiving Directivity Factor (RDF) improvement. The Hi-Z 4square appears to be the best bang for buck.

As of today grounds rods to mount the antennas have been made. A 1000′ roll of direct-bury CAT-5 cable is on hand to run power and control signals. A location has been selected about 500 feet north of the transmit antennas. A scheme to reduce the number of control wires so direction can be switched remotely has been invented. This receive antenna should coordinate nicely with the omega-matched tower transmit antenna upgrade this year.

One concern is how far apart to put the verticals for the best performance. The DXEngineering user guide says 135′ or one quarter-wave is optimum for 160. Other references says 80′ or 88′. An email was sent to Frank, W3LPL, to get the word from the master himself.

Hi Mark,
Optimum 4-square spacing for 160M receive is 67 feet.  Wider spacing produces higher signal levels but also higher side lobe levels.

Much more important is maximizing the spacing from resonant 160 metertransmitting verticals, towers more than 90 feet tall power lines andhomes or buildings that may contain RFI sources.   I would try for at least one thousand foot spacing.
Good luck!


Five hundred feet is do-able but 1000? Hmmm. We’ll see with a site visit tomorrow.

Cable was pulled from the shack to the 4-square site today which is 1000′ away. One thousand feet seems like no problem after today’s site visit. The site is very close to the Field Day site for 2019.

One cable is quad-shielded RG-6 and the other is direct burial CAT-5. One of the CAT-5 pairs will be used for direction control. The other three pairs will be grouped to provide power. Resistance of a single 24 gauge wire 1000′ long is 26 ohms at room temperature. Three wires grouped together will cut the resistance to about 9 ohms (8.77 to be exact). With 1 amp of current the voltage drop would be 9 volts (E=I X R). To provide 12 volts to a device the supply voltage will need to be 21 volts. Fortunately the battery voltage for the new inverter will be 24 volts. A linear buck converter (LM-317 voltage regulator) can be installed at the 4-square end and provide a regulated 12 volts. Per the instruction manual:

The DXE-RFS-3 phasing unit uses and distributes the voltage to power the active antenna elements.
For all four active elements, a nominal +12-15 Vdc at 250 mA current is required.

At only 1/4 of an amp load the voltage drop would only be 1/4 as much or 2.25 volts. If a 13.35 supply was used the voltage at the 4-square would be 11 volts. That might work but might be unreliable. Using a 24 volt supply and a buck converter is a more reliable choice.

Today the ground rods were driven for mounting the verticals. They were measured out to be within 1″ accuracy, using the 67′ side lengths recommended by W3LPL. The sides are precisely east- west and north- south. That makes Europe at 45 degrees the default direction.

Status: 4-square arrived today (some assembly required). The Quad Shield RG-6 cable has been measured out as accurately as possible and cut to length at home for the delay lines.

Next the excellent quality Snap-N-Seal connectors provided by DXEngineering were crimped on.

Tomorrow the cables will be taken to the remote site and connected. The verticals will be installed on the ground rods.

Installed, here is one of the verticals:

This is the hub at the center of the four verticals. The three delay lines are coiled up and strapped to the post. The gray box on the far side contains the voltage regulator (buck converter). The black box in the foreground is the DXEngineering control box.

Inside the gray box is a LM317 voltage regulator or buck converter. It converts the 24 volts input to a 12 volt output. A LM317 is used instead of a LM2596 because the LM317 is linear technology (analog) and does not generate digital hash like the LM2596. This method was chosen to carry 12 volts over a 1000 feet of CAT5 to overcome it’s inherent cable loss. In the picture below the blue/white pair carries the BCD data to switch the relays that control the direction.

Testing to see if the design works in the field shows good results. The gold thing is a 50 ohm resistor which simulates the load of the relay controller. (E = I X R, E = .25A X 50 ohm, E = 12.5 volts).

With the weeds looking very much like vertical antennas a wide shot of the 4 square doesn’t show much. It blends in quite well.

Performance is extremely directional as expected. A station to the northeast that comes in S9 completely disappears when the relays are switched to null it out. Come on winter and 160 season. It will be fun to use this.

Next, FT8 signals on this antenna were compared to the same signals on the 160 meter transmit verticals. Signals are stronger on the transmit antennas but there is no way to null out unwanted signals. A preamp is under consideration to bring up the gain where it will be even with the transmit verticals. The loss in 1000 feet of RG6 may need to be compensated for.

Status: completed (but always looking for improvements). To try to get a little more gain on 160 the jumpers were put in place to peak the response on that band. Gain is still low but it is working as designed.

January, 2021 update: Performance is amazing. A YouTube demonstration should be produced. A preamp was added at the 4 square to overcome the loss in the 1000’ of coax.

WSPR Station

Project 5 of 7 for October, 2020 – projects to keep sane during Covid-19 Lockdown

Status: Completed and on the air as of June, 2021

The object of building a WSPR station is to be able to see signals first hand real time that are coming into this qth. A band to operate on can be chosen more quickly and more efficiently. WSPR per se is explained here:

While it would be great to have a WSPR transmitter as well as receiver that is not feasible at the remote site or at home. The radiated signal from WSPR would cause interference to other services. A reasonable alternative exists and that is to receive only. Stations decoded will be posted to which shows a map of where those stations are located.

Hardware and software is about as simple as it can get. All parts are already in place and just need to be connected and configured. A computer that is already on site can run the WSJT-X software. An antenna that is already on site, the DXEngineering RF-PR-1B Active Magnetic Loop, can provide a signal on multiple bands. A receiver that will work well is the SDRPlay. The new model RSPdx is on site and is an excellent choice because of it’s additional bandpass filter on the low bands. It will enable monitoring of 630 meters all the way up to 10 meters. Virtual audio channel software will need to be installed to provide a software connection between the SDRPlay and the WSPR decoder. Virtual com port software will be needed for cat control to change frequencies. Power budget will be low because the pc and the receive loop already run 24 hours a day. The SDRPlay is the only additional power draw and it is insignificant. It plugs into a usb port on the pc and draws power from the pc.

Updates to follow as the project is implemented. Example display of is below.

It’s working! Check it out at Running on 30 meters alone provides this result.

All it needed was to reload SDRUno with the latest version, vspn port emulator software, and vb basic virtual audio cable software. A YouTube instruction video by the SDRPlay technical department helped a lot.

Final step will be to open up all bands, not just 30 meters. That works but the whole WSPR operation is not at all stable. This project is not done. It is stable so long as it is not disturbed but accessing the pc with remote desktop. That disturbance stops the WSPR operation.

It has been stable for more than a day by starting the applications on site and not using remote desktop. This is not a solution because we need remote desktop to reach other applications. Work in progress.

Currently working on an antenna on the house back in Denver to become the beacon antenna. How long before the HOA notices?

Update – June, 2021: Relocated to the site of the remote base, using Hustler 6BTV vertical antenna and Yaesu FT-817 transceiver. Running 1 watt on 80,40,30,20,15,10, and 6 meters. The computer is an Intel NUC i3 running Windows 10 and WSJT-X 2.4.1. Here is a typical example of performance. The best spot is Iceland hearing W0QL with it’s 1 watt and a vertical.

Above is an example of 30 meters early one evening. One watt and a vertical is amazing.


Project 4 of 7 for 2020

Status: Kit is sitting on shelf waiting to be assembled. Maybe for Spring?

The PSK31 portable qrp rig PSK-20 by Dave Benson was a big hit a few years back. With FT8 the current rage Dave has designed a current rig for FT8 with similar features. It’s the Phaser Digital Mode Transceiver. One is on order for fall field trips. Updates to follow.

Status: Kit arrived and is awaiting time for assembly.

630 Meters for 2020

Project 3 of 7 for 2020

Upgrading from last year’s 630 meter station is underway. The antenna will be reused. A new station transceiver was added during the year and can provide the 630m signals on the XVTR port. The biggest addition will be a linear amplifier to improve the transmitted signal. Actually, it’s a non-linear amplifier because the WSJT-X digital modes do not require the amp to be linear. A non-linear amp is just fine. The amp decided on is the K5DNL.

Two Hundred Watts? Yes, it’s legal because with a 2.5% efficient antenna the radiated power is a perfectly legal 5 watts.

On 630 meters, or 474.2 KHz, the antenna’s phase is very important. The rf current and voltage need to be in the same phase for the best radiation. An oscilloscope is used to make the phase measurement, with current on one channel and voltage on the other. When the sine waves line up the phase is perfect. K5DNL has available the hardware to sample the current and voltage to feed to the scope. Ken calls it the Scopematch. One was obtained along with the amplifier for this project. The scope in the shack here is the Hantek DSO5102P dual channel oscilloscope.

A big jump ahead happened when the decision was made to reconfigure batteries and build a 24 volt system temporarily. The amp runs on 24 volts. The main batteries for the permanent 24v system are on order but are still off shore.

Status: A temporary 24 volt supply has been set up and the project is awaiting time to complete it.

Portable Rig for the Field

Project 2 of 7 for 2020.

Currently the rig for the field is the venerable Yeasu FT-817. It has provided many hours of enjoyable operation as well as being a WSPR rig. It has the option of an internal battery. It has no internal tuner but doesn’t need one if used with resonant antennas like an end fed half wave vertical. Newer rigs on the market are very tempting and might stimulate an upgrade in the future but not yet.

Autumn afternoons in Colorado are a great time to get outside and enjoy the gorgeous weather and leaves in the mountains. Avoiding crowds is necessary these days so it’s a perfect opportunity to do a little hamming in the field. Keeping a rig as self contained as possible is a good idea in this scenario.

Fall River Road dreaming… A great location for a field operation would be around some trees that are not crowded with a lot of people in a place that tolerates a wire antenna. Experience has shown the PAR-20 to be a good antenna to throw up in a tree and make contacts and it does not require radials. Ideally a tree could be found that the PAR-20 could be invisible and remain in the tree for the next visit. It needs to be closer than Rocky Mountain National Park.

A battery was ordered this afternoon. The final choice was a 9800maH Li Ion polymer from eBay. Windcamp makes a great replacement for the Yeasu original which is twice the capacity of Yeasu’s. It’s expensive and shipping takes at least a month from China. A geniune Yaesu replacement is even more expensive at $119 especially when one considers the capacity is only 1500mAH. The Windcamp is 3000mAH. This external battery from eBay is almost 10,000mAH and it’s only $26. The plan is to strap this battery to the FT-817 with Velcro tape and fit the bundle in a backpack along with the PAR-20. A Palm mini paddle will fill out the equipment needed. Is there a good logging app for an iPhone?

Current status: Battery has arrived and looks like it will do the job. Connectors need to be installed and the project will be ready.