Archive for February, 2016

A reader recently requested I elaborate on the comms equipment battery charging system I carry in my Ruck.

First let me say that the setup I use is not what I would prefer but it works. I would prefer an ultra light weight system that I could attach directly to my Elecraft KX3 and charge the batteries using its built-in battery charger. The radios built in charger requires 13.8 volts dc but I haven’t found a pack-able panel that supplies that voltage. Most backpack/camping panels supply 5 vdc. That would require 3 sets of panels connected in series to get the necessary voltage. So, what I’ve had to resort to is removing the batteries from whatever radio I’m using, and charging the batteries in a charger that’s connected to the solar panels.

My current setup consists of the XTAR VC4 Charger and the Renogy Solar 14 watt E-Flex Solar Power Panel with dual USB ports.

I chose the XTAR based on its light weight and size, its ability to recognize and charge 4 different batteries at once and charge a wide range of Li-ion, Ni-MH and Ni-Cd batteries, plus pretty good Amazon reviews. So far its performance has been good. On the downside, it’s not waterproof,  but then I haven’t found one in its class that is. And while it’s not fragile, it’s not private-proof and should be packed in  your ruck accordingly. Last but not least, you have to use the XTAR provided USB to charger cable. Why they didn’t design it to accept a common double sided USB cable or micro to USB cable is beyond me. So until I can find a spare or make my own, I have 1 cable and no spare. That makes it a critical failure point. The old “2 is 1 and 1 is none….”.

I chose the Renogy 14 watt E-Flex solar panel due to the fact that the solar panels I installed with my home system were also purchased from Renogy and I have been pleased with them. They offered the E-Flex as a camping solar system and I thought for the low price, I’d give it a try.

The E-Flex weighs in at 1.3 lbs, folds up small, has dual USB charging ports and a pretty nifty charge indicator that glows brighter as the suns intensity increases. One downside is the flimsy attaching loops arranged around the perimeter of the assembly. Other manufactures offer heavy duty grommets that can be used for attaching points. Another is the small storage pocket does not seal completely, so be cautious what you store in it.

Charging time for 4 – Panasonic 2500 mAh Eneloop Pros runs about 6 hours depending on the available sunlight and angle.  Charging time for 4 – 2000 mAh Eneloop standards is about 4 hours.

Now you have to ask yourself, which is lighter and takes up less room in the ruck?  Lots of spare batteries or a few spares and the recharging system?  I would say that’s METT-TC dependent.

What is the Mission? Is it short enough that I can just take some extra batteries? Or is it a long term affair where the weight of the recharge gear will be less than the weight of the batteries. Will we be using vehicles instead of walking? Then we just use our cigarette lighter plug-in inverter and charger.

Terrain: If it is a long term affair, what will the weather be like? Cloudy weather would preclude using the solar panel. Will I have the opportunity to lay out a panel for a few hours during the day or will we be constantly on the move? Is the terrain heavily forested?

Troops: Am I or someone on my team in good enough physical shape to hump the extra weight over rough terrain? Do I have the space in my ruck?

Civilians: Are they on our side? Will we be operating in a non-permissive environment where laying out a panel might draw the interest of a civilian who then compromise our location?

I know, I left out Enemy and Time. You get the gist.

 

 

Yeasu 817ND

Posted: 02/02/2016 in Communications

A reader recently asked if I would recommend the Yeasu 817 as an alternate for the Elecraft KX3, in the tactical HF radio role. In my opinion, if the KX3 wasn’t available, the 817 would be my rucksack radio of choice. After all, the original 817 (now the 817ND) is a time tested radio that has been around for nearly 20 years and is just about bullet proof.

The price point for the 817 is seductive, averaging about half the price for a maxed out KX3. That being said, there are a few differences. The KX3 is an SDR (Software Designed Radio) that has a ton of options available and so many functions that it can be overwhelming to a new radio operator, while the 817 is pretty straight forward.

My list of requirements for a rucksack HF radio primarily focuses on a few items.

First is weight; my motto being ounces is pounds. The KX3 comes in at 1.5 lbs while the 817 comes in at 2.6 lb.

My second requirement involves power issues. Power out: KX3 – 10 watts, 817 – 5 watts. Not a big deal if you are fairly experienced with QRP. If you are new to ham radio, you might be a little frustrated initially with the limitations of either of these low power radios.

Power consumption is major concern when in the field with no resupply. I don’t want to charge batteries after every contact and I don’t want to pack around large batteries. I charge the 8 Eneloop AA batteries for my KX-3 using a small Renogy solar panel and XTAR battery charger while in the field. The normal rx power consumption for the KX3 is 150 ma versus 300 ma with the 817. The 817 is well known as a power hog but the problem can be partially mitigated if you get rid of the 1400 mah nicad battery pack that comes with the radio and go with the W4RT 2700 mah battery pack built especially for the 817. Look here:  http://www.w4rt.com/FT-817-Accessories/One-Plug-Power-FT-817.htm How you would charge the battery in the field would take some thought. I would probably change out the crappy stock battery access door with the W4RT door at the same time. Here is a pretty good link regarding the power issues with the 817: http://www.ka7oei.com/ft817_pwr.html

Third issue:  using CW and digital vice voice comms. Voice comms is pretty much out, this is a QRP rig after all. Both radios have internal keyers for CW and will support digital modes.

Fourth, is the radio rugged and waterproof. Neither is water proof or even remotely water resistant. Keep your radio in a dry bag. I would say the 817 is a little more rugged than the KX3 but you can rugged-ize the KX3 somewhat if you drop the extra bucks and buy the gemsproducts SIDE KX cover and side panels.

My fifth requirement is an internal antenna tuner. In a tactical situation, you shouldn’t use the same freq. twice. Unless you want to cut the antenna to proper length for each different freq. used, you need a tuner. You have that option with the KX3, but not with the 817. That problem can be solved by purchasing the Emtech ZM-2 ATU (Antenna Tuning Unit).  Find it here:    http://emtech.steadynet.com/zm2.shtml

The 817 has more band coverage than the KX3, which tops out at the optional 2 meter band. The 817 also includes the 6, 2 and 70 cm bands. In certain situations, I would caution the use of a radio in those VHF/UHF bands.

Just my thoughts. Whatever radio you go with, get out there and get on the air.

DOL

Dan Morgan