Accessory for the station

Sealed lead-acid accumulators

At the latest if one wants to become active away from the commercial power supply, the search for an alternative power supply begins. Although there are various accumulator types and high performance one-way solutions, I use mainly Sealed lead-acid accumulators. If one calculate the necessary capacity (in German), astonishing small types can be used. They are usable over years if still suitable charge methods (in German) and fundamental usage hints (in German) are used.

Charger for sealed lead-acid accumulators

I was in search of a small and lightweight accumulator charger for a sealed lead-acid accumulator. It's should work at 110 and 220 V and have a current limiting. Unfortunately I do not found an usable one so I modified the output voltage of an available power by Egston. A description of the modification is available. The sypply is avaiable also by Conrad Electronic (order no. 510997).

NiMH accumulators by Varta

During the preparations for a portable operation I make up my mind not to use my sealed lead-acid accumulators. For a long time I ogle with NiMH accumulators. They are ligther and smaller than comparable sealed lead-acid accumulators. But the offer is enormous. The accumulators are available both as single cells and as acumulator packs.
Finally I opt for single AA-cells by Varta, which are usuable for high-current applications (not the normal ones). They possess a capacity of 2700 mAh with 1,2 V for each cell. For a transceiver operated with 12 V are 10 cells to be used. You can unload the cells with up to 4800 mA (4.8 A) and down to 0.8 V. Thus a transceiver can be operated down to 8 V.
The used cells (four-pack, order no. 250484) and suitable holder (order no. 615617) are avaiable by Conrad Electronic. For charging I use a ready-made charger for NiMH accumulators. A tip: Buy as much cells as you need for 2 accumulator packs. While a package of 10 cells is loading, you can use the second package.

Charger for NiMH accumulators by Basetech

There I stood now with my 10 NiMH accumulators. I own a suitable charger, but it can charge only 2 cells at the same time. Devices, which charge 4 cells one finds many, such for 8 cells already less. I found only one charger, which can charge at least 10 cells at the same time. It is the BTL12 labeled Basetech, which is i.e. available by Conrad Electronic (order no. 200012). I selected consciously a device, that don't uses high-speed charging. It charges the cells with 250 mA (trickle charging current 25 mA). The charge process takes longer (approximately 15 h in relation to 3 until 4 h), but the cells are take care in such a way. To emphasize is, that the BTL12 supervises each cell separately and the device uses the so called -ΔV disconnection. The charger can be runs as well with the power adaptor from 100 to 240 V as with an adaptor cable from the 12 V car. Dimensions: 223 mm x 34 mm x 98 mm, Weight: 217 g

Straight key by Kent Engineers

This is a mechanically solid and steady straight key by Kent Engineers, which I use since a have a licence. Due to its weight (1200 g) it is however not much conditionally for the portable operation. What a pity! This key is also buyable from Wimo.

Modification: The nut for adjusting the resetting force can solve itself with the use easily. I screwed therefore an additional nut on it. In the picture this is visible as a silver colored nut by the rear part of the key.

Squeezer by Kent Engineers

So far yet I did not learn it to serve a squeeze key correctly and fast. Therefore this key by Kent Engineers was long time standing in the original packing up in my shack. This key is also buyable from Wimo.
The key is solid and due to it weight of 1200 g and the rubber feets are slip-resistant. The quality is the same as by the other Kent keys use by me. My key had found a new owner.

Wabbler by Kent Engineers

This is a mechanically solid and steady wabble-key by Kent Engineers, which I use since lately. Due to its weight (1100 g) it is however not much conditionally for the portable operation. What a pity! This key is also buyable from Wimo.

Modification: The nuts for adjusting the resetting force can solve itself with the use easily. I screwed therefore two additional nuts on it. In the picture this are visible as silver colored nuts by the side parts of the key. Additionally the replacement of the original springs made itself necessary, since the adjustment of the resetting force did not occur sensitiv enough. After softer ones were inserted, this succeeded however without problems.

Funky - a key using pressure sensors

Some surplus electronics companies are offering relatively inexpensive pressure sensors. Actually I wanted to see what I could do with one many times. Amazingly the sensors "played" well, so I started immediately to look for a project. I had long wanted a durable and light key. Therefore I decided to make a key using the sensors. A description of this key is available. The sensors I used are buyable from Conrad Electronic (FSR-151, order no. 182546).

PS. In the meantime Chuck Olson (WB9KZY) has undertake some futher experiments with this key and ascertain, that the key works better without the pressure sensors. His variation is named "Touch Paddle" and he sells it via Jackson Harbor Press (Photo by WB9KZY).

CWF - finger morse key by Gerd Lienemann, DF9IV

If you dissatisfied with the attitudes or the weights of morse keys then this key is exactly the correct key for you. It lies always ideally between the fingers and is extremely light. A description of this key is available.

Minkey by Englmar Wenk, DK1WE

The Minkey is intended specially for the use outside of the shack, because it weighs only 55 g. In spite of the small size the force and the hoisting can be adjusted sensitivly. It possesses a slide-restraining layer on the lower surface, but one should hold it with one hand during keying.
This key was buyable from QRPproject and from Funkamateur. The key is not any longer manufactured.

Palm Portable Key by Palm Radio

The Palm Portable Key by Palm Radio is a straight key, which is housed in a stable aluminium profile in tension. The mechanical system is very precise with zero backlash and you can it slide-in in the housing. The leverage effect is adjustable in 6 steps from 60 to 250 g with a snap-in locking device. Dimensions (slided-in): 25 mm x 25 mm x 79 mm.

Mini Morse Key by Markus Baseler, DL6YYM (BaMaTech)

The Mini Morse Key by Markus Baseler, DL6YYM, is my first straight key, which possesses two magnets instead of the otherwise usual spring. Thus a very sensitive attitude of the force is possible. The lever arm is embedded in two very small ball bearings, which are not accessible from the outside and which thereby cannot get dirty thus also with the rough portable use. The key is manufactured from high-strength aluminum, which was dark red anodized. The button is manufactured from black plastic. The key is supplied with a thin, very flexible and nevertheless robust cable (1 m long), which is already attached including a 3,5 mm jack. Markus has manufactured this morse key primarily for himself, however offers it over BaMaTech also to other interested people.
Technical data: dimensions of the baseplate 40 mm x 30 mm x 8 mm, dimensions altogether 53 mm x 30 mm x 23 mm, mass: 40 g, slip-resistant rubber feets

Dummy loads so far the eye extends

Sometime you need for tests on a transmitter or for comparative measurements a dummy load. Of course you can buy it nearly everywhere. Such "monsters" are however not necessary for QRP power! What should I do as QRPer e.g. with an enormous and expensive dummy load for 50 W, 100 W or more? Therefore I would like to tell you a few suggestions for small and cheap dummy loads.
A commercial variant (picture left) is offered as terminal resistor for measuring instruments. They exhibit for 50 Ω and can handle up to 1 W.
If you want to build your own dummy load, then it seems to fail first because of the offered resistors. 50 Ω resistors with the necessary power are require large heat sink. Take therefore simply different resistors! Remind you of the Ohm's law and the parallel and/or series connection of resistors. In each good electronic shop you can buy non-inductive resistors for 0.25 W or 0.5 W. In some stores also such for 1 W or 2 W. Resistors made from carbon or metal oxid are good usuable. You can reread a few possible combinations here. If you solder this resistors to a suitable plug (picture right), then you receive a outstanding dummy load. In addition, you can solder SMD resistances on a PCB. No borders are set to your fantasy!