Ever since I’ve started being a ham (last year, hi), I have been trying to work on a light and quick-to-setup station, because I do not have a real station at my QTH and do most of my QSOs as /P. I started with an FT-817, which is a nice radio but it’s power consumption and weight limit portability.
I have been doing mountaineering in summer and winter for ages, and for longer hikes and skitouring trips, there is very limited space and weight left in the backpack for ham radio gear; I mean, it does not make sense to have super-light harnesses and ropes etc. if I have to carry a 65l back-back for my ham gear, hi.
I quickly came to the conclusion that CW is the way to go, and started learning CW about a year ago.
My goals for an ideal station are the following:
Lightweight and compact (that is clear).
Rapid setup: In the beginning, I tried packing an MTR with all kind of stuff in bags, which was compact and lightweight. But it takes a lot of time to unwind and connect everything; parts can be lost, and it is a pain to use many distinct parts e.g. in 50 cm of fresh snow. Also, I often have very limited time on the summit, so loosing 10 minutes to unpack my rig is problematic.
Sturdy and watertight: I want to be able to squeeze my gear into a full backpack with crampons, carabiners, etc. in a hurry without fearing to break the key or other parts. The MTRs slide switches are e.g. easy to damage. Also, at least when stowed away, rain and some snow should not harm.
So here is my current station, inspired by the GoBox concept by Tom, OE2ATN, see https://www.oe2atn.at/tom/kx2-gobox-2016/:
- Mountain Topper MTR 3B, gives 40-30-20m, which is all I need, removed from its metal case
- Pelican 1040 case, http://www.peli.com/eu/en/product/watertight-protector-hard-cases/micro-case/standard/1040/
- 4.8V 4 x AA Nimh battery pack; fully sufficient capacity for several hours, much less risk than Li-based batteries
- Two step-up converters that generate 6 and 12 V DC from the battery, 12V for full 5W and 6V for 1 W for tuning and QRPP
- Simply battery voltage monitor with two LEDs, a zener diode and a transistor - green LED shows sufficient voltage to not overload the step-up-converters (their input current increases as the input voltage drops), red LED shows undervoltage so that you can stop before the Nimh batteries get damaged. I decided against an automatic turn-off circuit, because I want to be in control to finish a QSO.
- SWR meter (rather: indicator, hi) and power indicator with LEDs, based on the design by DF3OS, see http://www.sp5jnw.sem.pl/konstrukcje/atudf3oshtm/atudf3oseng.pdf
- Volume control (simple 1k micro potentiometer) to adjust headset and speaker volume
- LM386 amplifier and tiny control monitor, so that I can be away a few feet from the radio, e.g. during CQ loops
All components are mounted on a front panel designed as a 3D print part. I will later replace that by a laser-cut aluminum one but wanted to test the concept first.
The front panel includes a few metal washers so that a Palm Pico Single key can be mounted in various angles via its magnets and can be retracted during transport.
The charging of the NimH batteries is done by an external plug-in power supply (https://www.amazon.de/dp/B016WEOMN8/) that supports 1 A current and includes all circuitry for intelligent charging.
For longer activations, external batteries can be plugged in via the same DC connector.
I am very, very happy with this setup. I can be QRV within 15 seconds + antenna set-up; you cannot loose any part, and the complete station without antenna is just 559 grams. The batteries allow for many hours of operation.
As an antenna, I use the trapped 3-band EFHW design by Heinz. HB9BCB (Trap EFHW and Coupler and https://hb9sota.ch/wp-content/uploads/2016/12/Slim-EFHW-Koppler.pdf). The antenna is ca. 16m long and can be used as an inverted L, inverted vee, sloper, and horizontal with very good performance (spots in VE and USA with 5 W are common). When there are no trees etc., I use the 6m mast from Lambdahalbe.
So my total station is
Rig with battery, paddle, case, earphone, SWR meter etc: 559 g
Antenna with winder and EFHW matching unit: 131 g
Golf ball + fishing line for trees: Lees than 100 g
Optional: Mast: 650g
With the mast, one is slightly over the 1k limit, of course.
I plan to document the whole project once I have finalized it, but this will take a while.
The only things I am missing in this setup is a VFO knob (I am considering to add one to the MTR3B by combining a rotary encoder with an ATtiny; other have done this already), and maybe a direct frequency display (by intercepting the frequency values sent from the uC to the DDS inside the MTR). I was also thinking of adding a simple zero beat indicator. But then again you could also simply take an Elecraft KX2, hi.
73 de Martin, DK3IT