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This article details how I set up a HF/VHF/UHF manpack radio.


Design goals

Radio RF Output:

Minimum of 20W, preferable to have optional 50W+ available if needed

Radio Frequency coverage:

HF, 6 meters, 2 meters, and 70cm

Radio Modes:

FM/SSB/CW/packet

Radio receive current:

preferably less than 700mA

Tuner:

10-500ohm minimum, preferable little to no idle current

Battery:

sufficient to handle a weekend without recharging

Power:

Battery, AC, or solar

Antenna:

Vertical or dipole with optional voltage balun

PC:

Small netbook capable of digital modes

Size:

Everything fits within a pack suitable for airplane carry-on (21x14x10").

All items:

Weight as minimal as possible !

The Radio

Here is a quick rundown of the radios I considered:

Military radios (PRC-104, PRC-132, PRC-138, PRC-320, PRC-1099, PRC-2000, AEG SE-6861)

All of them are good radios. Only problem is I want HF/6/2/440 so I'm stuck

with looking at amateur radios.

Commercial radio VX-1210 ($1400+, 7.1lb w/batt, rx: 500mA, tx: 3A/5W, 5A/20W)

Very tempting but is HF only. Has option for internal autotuner and can be

set up for VFO operation. Battery is 14.4v 4AH.

Commercial radio Mobat Micom 3 Pathfinder (25W)

Excessive cost for this project. Otherwise a great radio !

Outback radios (QMAC, Barrett, Codan)

QMAC HF90 excessive cost & no longer made, Barrett 940 too heavy (18.5lbs w/tuner battery)

Barrett 2040, Codan 2110 excessive cost.

FT-817ND ($600, 2.6lb, 8-16v, rx: 300-500mA, tx: 2A/5W):

Tempting, and would pair nicely with LDG Z-817 tuner.

Only problem is I want 20W+. This could be accomplished with a Tokyo High Power HL-45B

amp ($900, 3.4 lbs, 8.5A/45W, 160-6m) however I think the price is a little high.

Regardless this is a viable combination and has the benefit of low RX current.

IC703+ (discontinued, 4.4lb, 9-15.8v, rx: 300-500MA, tx: 3A/10W, HF+6M)

Nice radio, big and easily readable display, built in autotuner. Wish it did 2m/440

like its bigger brother (IC-706).

IC706MK2G ($800, 5.5lb, 11.8-15.8v, rx: 1800-2000mA, tx: 20A/100W)

RX current way too high, VHF frontend easily overloads. Nice display as with the IC703

above. The RX current is a deal breaker for battery ops.

IC7000 ($1200, 5.1lb, 11.8-15.8v, rx: 1300-1600mA, tx: 22A/100W)

Nice radio. RX current better than IC706 but still a little on the high side for battery ops.

FT-897D ($900, 8.6lb, 11.7-15.9v, rx: 600-1000mA, tx: 22A/100W)

HF/50 MHz:5 watts = 4.0-4.7 amps 10 watts = 5.3-6.4 amps 25 watts = 7.3-9.2 amps 50 watts = 10.6-12.9 amps

144 MHz: 5 watts = 3.4 amps 10 watts = 4.2 amps 25 watts = 6.3 amps 50 watts = 9.4 amps

420 MHz: 5 watts = 4.2 amps 10 watts = 5.6 amps 20 watts = 8.7 amps

Designed for field ops and has room for internal batteries (13.2v, 9AH) however the batteries

add an additional 6.5lbs to a radio which is already heavy at 8.6lbs. One option is to run your

own external battery which gives you room to install an internal 120V power supply. Overall

I really like this radio but its ruggedness will cost you in weight. You can get the FT-857D

(sacrificing the 897's rugged case and internal battery space) and save 4lbs on your back.

FT-857D ($800, 4.6lb, 12.4-15.2v, rx: 600-1000mA (spec) 650-700mA (green/red backlight) 590mA (backlight off), tx: 2A/5W 5A/15W 22A/100W)

Unlike the FT-897D above, this radio does not come with a TCXO. By the time you spend $100 on

the TCXO you end up with about the same radio as the FT-897D for the same price. Comparing the

FT-857D to the FT-897D has some pluses: 4lbs lighter, detachable head, and easier to mount mobile.

The minuses are we don't get the rugged case and battery space. I don't think either of these

minuses will matter as the radio and batteries will end up in a pack. One other thing to note is

both the 857 and 897 will automatically limit the radio to 20W when running on battery power

(by grounding the brown wire on the power connector).

Spec says voltage is 12.4-15.2, manual says 11.73-15.87.

The 857's signal will start sounding bad at about 11.75v.

Given everything above it came down to deciding between the FT-857D and FT-897D.
I chose the FT-857D because its 4lbs lighter than the FT-897D. Every pound counts when backpacking !
The radio is best equipped with: tcxo-9, keypad mic, (2) W4RT/inrad.net filters.

The tuner

For honorable mention we have the long-discontinued Kenwood AT-130 which is a very small 80-10m(+WARC)
manual tuner (6 x 2.4 x 6.3 inches, 3.5 lbs.). For field ops I prefer a small autotuner. Yaesu makes the
FC-30 ($170, 17-150 ohms, 3.1 x 1.8 x 10.2 in, 2.2 lbs) however its 17-150 ohm tuning range is quite
narrow compared to the LDG product line.

Here is the breakdown of the LDG products I looked at:

$200 LDG YT-100 (latching relays) for 857/897 100w = 1.5lbs 4-800 ohm 7 x 7 x 2

$200 LDG AT-897+(latching relays) for 857/897 100w = 2.0lbs 6-800 ohm 11.5 x 3.25 x 1.5

$160 Z100+ ? 125w 6-800 ohm 5.5 x 5.5 x 1.5 1 lb w/o batts

$170 Z11pro2 6-1000 ohm 7.7 x 5.0 x 1.5 1.5lb w/o batts

I ended up going with the Z11pro2 as it can autotune based on RF sense which keeps the CAT and ACC ports free. This is good because we
need both ports for our data interface. Another bonus of RF sense tuning is it makes the radio PC-ALE capable provided the antenna is
tunable on whatever ALE frequencies are to be used.
The device on the left is the data/soundcard interface

The battery

I initially considered using 11 Accupower NiMH low-discharge "D" cells (10aH, 1.25v, 145g ea.)
This would give us 13.75v, 10aH at 3.5lb for about $110.

After more research I went with (8) 40160S LiFePO4 batteries (16AH/ea). This project really only needs 4 of these batteries however I opted to build two battery packs. 4 of these batteries in series gives you around 13 volts.

Paired with each battery pack is a circuit which protects from overcharge/overdischarge/overcurrent. It also keeps the batteries balanced while charging. After a long search for a suitable lightweight container I found the 4-battery pack fits perfectly into a "Huggies" baby wipe plastic box. I cut a small slot in the box for a short piece of velcro which holds the lid closed.



Notice the top door works great for the powerpole.

Here is a view of the internals. The protection circuit board is on the top.

The AC adapter/charger

I wanted enough beef for the radio to do 20W off the adapter. I ended up getting IBM PA-1121-0711 16V 7.5A Notebook Power Supply Adapter for about $14 off ebay. It is relatively small and weighs 0.4 lb. I run it through a bridge rectifier which reduces the voltage to 14.8V which is suitable for operating the radio and charging the battery pack.





The solar panel

PowerFilm F15-1200 20W (10.5 x 6.5 x 0.6" 1 lb )
Nice compact and light panel but a little pricey at $10/watt. I would have gone with their 30W panel but it was even more overpriced.


Here is the solar panel and the computer File:W7ki solar panel and netbook.jpg

The computer

EEEPC 1000h. Small battery-efficient netbook with 10" screen. Used it because I had it on hand. Any netbook would probably do ok so long as it has mic/headphone jacks. One bonus of this particular computer is you can feed it 12VDC direct.



The Data Interface

Homemade. Nothing fancy, just some audio isolation transformers, a level converter, and a PTT transistor.
The data interface and the tuner are attached to the mobile mounting bracket with velcro. Note how the mobile bracket is angled such that the front of the tuner is slightly elevated. This was done to give some clearance to the radio speaker.


The antenna

I looked at a variety of compact antennas (Outbacker Joey, Outbacker Stealth Plus, ATX-W38 walkabout, ATX-DHP, and a handful of others. I could not find anything that would collapse to under 18 inches (requirement for the pack I'm using). It was probably just as well since many "portable" antennas are helical which I personally despise.

Fortunately I found an 8.5' collapsible aluminum pole made for measuring snowpacks and after some tinkering it worked like a charm.

Paired with a couple of 18" aluminum extender rods and a large tapped coil it turned out to be a usable antenna.

Obviously running a huge coil with a short antenna is about as worthless as a short helical so its important to remember to use as much whip or longwire as you can if you are less than 1/4 wave.

For a horizontal option I built a tapped voltage balun which attaches to a vertical extension arm and connects to two spools of wire.
The wire spools can also be used as a counterpoise for vertical configurations.
The device at the bottom is a carbon fiber camera monopod which we use as a vertical extension arm.
The device at the top is a carpal tunnel wrist strap which is used for attaching the monopod extension arm to the pack aluminum extension arm.
The antenna wire is wound on Coleman camping clothesline spools.

For VHF/UHF I have a 17" dual-band antenna or another option for VHF only is putting one of the 18" aluminum rods onto the 1" antenna mount.
6 meters can be done with the 17" antenna on top of both 18" rods.




The pack

I looked at dozens of packs before settling on the Jansport Driver 8. Most other packs were either oversized and/or too heavy.

My reasoning for a 21x14x10" size limit is so you can carry this on a commercial airplane if you are traveling. You certainly wouldn't want to check this as luggage as it would probably get destroyed by handling or stolen.

Two main things I liked about the Driver 8 are the wheels and the telescoping arm. The telescoping arm is wonderful because it is very sturdy aluminum which allows you to securely attach an antenna to it. This is great for manpack operations if you want the antenna up while you are walking around with the pack on your back. It also works great for fixed operations as the pack itself can be used as an antenna base. The wheels not only give you back a break where smooth surfaces are available, they also give you the ability to easily lay down the pack when assembling a long antenna. Its like having a mini fold over tower.




Construction and setup

A complete materials and sources list is at the end of this article.


Extension arms and antenna
To make the aluminum extension arms you need a 3 foot piece of aluminum rod. Cut the rod into 3 pieces, 2 of them will be 17 inches long and the third piece will be the remaining 2 inches.

Take a 21/64 inch drill bit and drill about 1.5 inches into both ends of the 17 inch rods. Be careful to drill straight. Once this is done tap threads into both ends with a 3/8-24 tap. Tapping threads into aluminum generates a tremendous amount of head so remember to tap slowly and use an oil lubricant. Right after tapping these rods I bumped one of them with my arm and got a very nasty burn.

Once the tapping is done thread a 3/8-24 RHT stainless stud into both ends of the rods. Then, for each rod, put a 3/8-24 jam nut over the stud on one end and put a 3/8-24 x 1-1/8 Hex Coupling Nut over the stud on the other end. When you are done it should look like the picture below.


Now grab the remaining 2 inch piece of aluminum rod. Drill one end 1 inch deep with a size F (.2443 inch) bit then drill the other end 1 inch deep with the 21/64 inch drill bit you used for the other rods. Tap 5/16-18 threads into the size F end and 3/8-24 threads into the 21/64 end.

Take the aluminum antenna, remove the lanyard string, push in the lower release spring button and shove it up the tube a couple inches, and tap the bottom for 5/16-18 threads. The two photos below show the start and finish of tapping the threads. I seriously do not recommend using vise-grips as shown in the photos. The antenna deforms very easily. It would be much better to lightly use a vise which can distribute the grip better with much less crush force. Again, BE VERY CAREFUL NOT TO CRUSH OR DEFORM THE TUBE. I darn near destroyed the prototype using vise-grips.






Next we take a 1.5 inch 5/16-18 stud and thread half of it into the antenna. This is generally difficult to do so I recommend tightening two 5/16-18 nuts against each other onto the stud and use the outer nut with a wrench. Once the stud is threaded into the antenna you can thread the 2 inch aluminum rod onto the stud, then thread a 3/8-24 stud into the other end of the rod. Put a 3/8-24 jam nut onto the exposed threads. What you have done here is built a 5/16-18 to 3/8-24 thread adapter. The photo below shows what the finished product should look like.





The next step is to modify the antenna to make it conductive. The anodized surfaces do not conduct electricity so you need to take some sandpaper and sand out the inside of the bottom of each rod (about 3/4 inch should do). Another issue is the tapered inserts which are crimped into the top of the rods. These don't conduct either so you need to lightly bond them with an arc weld. This should be done with a MIG or TIG welder. Remember to sand the surfaces first, including the entire tapered section. I cheesed mine by using two truck batteries, a pair of jumper cables, and some real thin aluminum wire. Some people refer to this as hillbilly arc welding. Please don't do this unless you know the risks, know what you are doing, and you are using appropriate eye protection. Here is what mine looked like when it was done.



If you are wondering why I went through all this trouble it is because I could not find any non-telescoping antenna which could extend to at least 8 feet and collapse to under 18 inches.


The coil is made from a 7 3/4 inch piece of 4 inch diameter drainpipe with a drainpipe cap on each end. To make room for more coil turns we cut 1 3/8 inch off the end of the drainpipe cap. You need to cut two end caps.



Then drill a hole in the center of each cap to fit a 3/8-24 stud



Now we take a piece of 1/4 inch schedule 80 pvc pipe and drill/tap it for 3/8-24 threads the same way you did the aluminum rods (except please don't use lubricating oil). Its important to use schedule 80 pipe as it has the correct inside diameter for tapping threads. The pipe should be about 7 1/2 inches long and later you might have to make some slight length adjustments for fit. Once your threads are tapped you can thread a 1.5 inch 3/8-24 stud into each end then put a 3/8" USS Flat Washer over the end (see photo below). Put one end into an end cap, put a 3/8" USS Flat Washer on the outside of the end cap, stack one 16-14AWG 3/8 ring terminal on top of the washer, and secure it with a 3/8-24 x 1-1/8 Hex Coupling Nut stacked on top of the ring terminal.







Put the other end cap on. On the outside stack a 3/8" USS Flat Washer, a 16-14AWG 3/8 ring terminal, and a 3/8-24 jam nut.




To make the coil, glue 4 pieces of .065 Nylon Edge Trim as shown in the photo. When cutting them to length, remember to offset each one to correctly accomodate a spirally-wound coil. Once this is done, drill a .065" diagonal hole from the edge of the cap through the top of each cap (see photo), thread the wire through the hole and wind the coil with .064" (14AWG) tin coated copper wire. Remember to keep tension on the coil or else it will wind loosely. The wire is stiff and doesn't come off the coil perfectly so there will be some manual coil alignment/straightening to do after the coil is wound. Once the coil is wound, put the ends thorough the 16-14AWG 3/8 ring terminals, then cut & solder. Be careful of heat damage to the plastic while soldering. Its usually best to loosen the end nuts prior to soldering as it will conduct less heat away from the ring terminals.



The coil tap is an EZ-Hook XM attached to a 16-14AWG 3/8 ring terminal with an 11 inch piece of 22-gauge 7-strand insulated hookup wire. Attach the ring terminal above the coil ring terminal as shown in the photo.



The EZ-Hook XM works great for 17AWG wire however its a little small for our 14AWG coil. The hook can be slightly adjusted with needlenose pliers to fit the 14AWG wire. The picture below shows the modified hook profile.





The balun is based on a design by WB6ZQZ. His design includes both a bifilar and a quadrifiler transformer. We are only interested in the quadrifilar transformer. Here is a link to instructions on how to wind the quadrifilar transformer:
http://www.antennalaunchers.com/trb/photos.html

Use 16ga enameled wire and a F-125-K toroid. Once the transformer is wound you can mount it on a small piece of plastic with holes drilled for the wires. Attach the wires to each other as per his schematic diagram and PC board photos.

Mount the completed toroid into a 3x2x1 inch Jaycar UB5 clear jiffy box. Install an SO-239 connector into the bottom of the box. For terminals I used (4) 1/4"-20 x 3/4" bolts/nuts/wingnuts which are available at a home-improvement store. Label the terminals for Common, 50, 25, and 12 ohms. Attach a short piece of velcro to the back side which allows for mounting.








The antenna mount uses 1/4-20 hardware. I recommend replacing two of the nuts with wingnuts. Cut an 11 foot piece of Belden 8219 RG58A/U and loop it twice through two Laird LFB187102 ferrites as shown in the photo below. The coax fits tightly and we do not want to stretch it while pulling it through the ferrites so use a non-petroleum lubricant (I used cooking spray). Once this is done you can put UG-175/U reducers on the cable and solder a PL259 connector on each end.





The antenna wire is spooled on a (2) Coleman 827E140T colthesline reels. Each Coleman reel comes with 21 feet of nylon cord. Pull all the cord out and cut off 13 feet so there is 8 feet remaining on the spool. Attach 59 1/2 feet of 22AWG insulated hookup wire to the end of the nylon cord. You can do this by stripping the end of the wire and pushing it through the middle of the nylon cord about 1/2 inch from the end, then secure the end of the nylon cord by lightly melting it with a lighter or soldering iron. Now you can reel in the wire. If it gets stuck you can open the reel with a 1/3 turn of the enclosure shell. Attach a 16-14AWG 3/8 ring terminal to the end of the wire.


Each battery pack is made of (4) 40160S LiFePO4 batteries with a battery management circuit put into a Huggies wipe box. The battery management circuit sits on top of a plastic board which is an Akro-Mils 40150 (3.3 x 7.7 x 0.1 inch). Mount the batteries in the plastic holders, wire them in series with the bus bars, mount the battery management circuit, then wire it in. I recommend using a 30 amp fuse as pictured. Once this is done attach a 30A (12-14AWG) Powerpole connector with 12-gauge wire.






The data interface consists of audio isolation transformers, an RS232 level converter, and a PTT transistor. The audio circuit is per the "KK7UQ Interface Model II" circuit although I chose not to use the potentiometers and solid state relay in the original design. The original design and documentation can be found here:

http://kk7uq.com/html/download/Manual2E.pdf
The RS232 level converter is per a circuit attributed to OE1RIB.

Use a USB-serial converter if your computer doesn't have a serial port. I recommend using converters with the FTDI chipset for best performance and OS compatibility (I used USBG-RS232-F12 from usbgear.com).
Here is the actual circuit I used to build the data interface:





Remember to leave clearance for the jacks and switches when laying out the components on the PC board.





Velcro attachment





Mounted to radio





Cable detail on backside. I used a short piece of cat5 network cable wired like this
CAT RD W-Br
CAT TD W-G
CAT + Br-W
CAT GND G-W

Data Out12 O-W
Data In W-Bl
Data PTT W-O
Data GND Bl-W


The mini-din connectors go in very tight so beware of non-functioning or partial connections when you do this. Once you get them seated properly they work great and stay in place. Make sure to notch the back of the connector sleeves so the cables can exit at 90 degrees.





In the above photo you will also notice a connector/adapter contraption covered with electrical tape. These UHF right-angle adapters were used because the radio rests on its back side in the pack and we don't want the weight of the radio sitting on a PL259 connector and pinching the coax. All UHF right-angle adapters are not created equal. Most of them are garbage and use a small internal spring to connect the center conductor. The correct part to use is Amphenol 083-1AP UG-646/U. The adapter connecting the radio to the tuner is two of the Amphenol right-angle adapters connected with a short piece of LMR-600 with the center conductor diameter ground down from 0.176" to 0.157". As you can see in the photo below, this arrangement makes the back of the radio very compact which helps it fit in the pack.