The HALF KG multi-band HF Challenge

One KG challenge accepted. My multi-band HF complete set up is about 500 grams.

To do it:

Radio is an MTR, small, light, and functions quite adeqautely. I get as much as six watts out after careful tweaking.

Paddle is the Pico-Palm, weighs 16 grams. I put a little bit of steel on the side of the MTR, the paddle sticks to it.

Battery is a 3S LiPO 250 mAH. I seem to average less than 5 mAH per QSO, so it is plenty for an activation. It is velcroed to the side of the radio.

Earbuds are on a retractor. They stay plugged into the radio, just pull and play.

Eliminated connectors, coax, or any feedline. I tape the EFHW wire to the pole with a about a meter and a half of slack left. Wire end has a 2 mm plug on it. The end of the wire doesn’t radiate anyway, so no reason not to use it for the feedline.

Eliminated any tuner. Instead use an impedance transformer built inside the MTR. it consists of a capacitor and a toroid, would for 81:1. The wire is cut to be 1.1:1.

The back of the radio supports a single cut to fit sheet of write-in-the-rain plastic paper for the log. I hold the radio in one hand, write and key with the other.

Writing utensil is a mini-spacepen, 4 grams, writes upside down underwater, on butter. The pen is tethered to the radio, so I can just drop it if I want to.

Pole is 18 feet tall (5.5M) collapses to 2 feet, and weighs about 7 ounces.

Antenna is 53 feet of #28 teflon wire with two homemade traps using T50-6 toroids, each trap weighs ten grams, operates 20/30/40 instant, no tune band changing. It is wound on a figure-8 winder, total weight about 70 grams.

Set up or tear down is typically 4 to 6 minutes once a suitable location is chosen.

The pack weighed more than the entire set up, so it had to be replaced. I now use a pack made of nylon gauze that weighs only about 200 grams. < Ultra Vest 5.0 | Ultimate Direction >

Water is the heaviest burden, now have a filter/straw so that I can drink from any streams encountered, OR, I have a filter in the hose to my hydrapak, so i can carry less and refill from streams.

Essentially all our activations are over 10,000 feet (about 3,200 meters), with some as high as 14,400 feet. It is a whole lot better to be lighter!

73, Fred KT5X (aka WS0TA)


Really 6 watts @ 11.1 volts out from 3xBS170 ???
Transmit current? PA efficiency?
… or did you mean 6 watts out of the battery :wink:

“careful tweaking”: simply by spreading the turns of L12, L14 and L16 or by something else?

1 Like

Hi Fred,

I’m still way out to reach half a kilo here!
Your setup is so optimised that is going to be difficult reaching you soon…
Stay tuned for pictures of your gear on a summit.
Take care on hills and keep well hidrated please!

VY 73 de Ignacio

Hi Fred,
I have an MTR too - marvelous box - but I’ll never do a half kg challenge as I always carry 1 litre of water, first aid kit, map, compass, emergency snack, GPS, torch, pocket knife, and a few other bits.

Interesting exercise though to get the weight down.