Very Simple Straight Key

I used to have a very simple "emergency" key with my KX3, just a pushbutton (the TURBO switch from an old PC, remember the days when PC's had a turbo mode ?).
I didn't use it very much because it has a bit too much travel for good keying ...

I did make several paddles in the past, all made from scrap pieces of PCB.
One of those was made after the idea of Carel PA0CMU for a double paddle : http://members.ziggo.nl/cmulder/paddle.htm
Carel based his design on the idea of  NB6M for a single paddle :

So I got the idea to make the simplest straight key, and still have good results. This is what I came up with ... you need :
- 2 pieces of single sided PCB, approx. 2 x 5 cm, may vary along your taste ...
- Two contacts from an old relay (cleaned with a blue ink eraser)
- Dremel cutting tool
- Soldering iron
That's it !

I took a picture when everything was cut to size, ready to start soldering.
(I didn't make a drawing, just drew some lines without even measuring , hi)

I took the two small pieces for the side posts from another piece of PCB,  but you could actually cut the center piece in two. The excess PCB of these post will be cut off later anyway.

First solder the contact strips in place (take care : don't put solder on the contact points !).
Then mark two lines on the bottom piece and solder the posts in place.
(this picture is from a second model with wider "arms" for some more resistance)
Also remove a strip of copper to isolate the front contact from the rest (all the rest will be GROUND).

Then put some spacer between the contacts and hold both parts in place with a clothespin, like this:

If you are satisfied, solder the arms in place, they can easily be repositioned later if the contact distance is not what you like.

Then put a capacitor of 10nF over the "gap" and connect a cable with a 3.5 mm jack.
For my KX3 I have to use a STEREO jack, but using only the tip and sleeve connections, this may differ for other brand of transceiver.

I made two different keys, one has a fixed cable, the other has a 3.5mmm connector, to be used with a seperate cable. I can fit both this key AND a mini single-lever paddle in a film can !

Have fun !



Frog Sounds QRP CW kit build

This is my attempt at the Chinese "frog sounds" QRP kit.
After ordering it for exactly 9.99 EURO, it arrived some 3 weeks later. Everything was in one little plastic bag, and even had 3 sheets of instructions !

A well made PC board, and as I found out during the build ... too many components (mostly capacitors and one transistor), and one missing component, an electrolytic cap of 1µF, not too bad, I have those in my junkbox. Three sockets are provided for the IC's, nice. 

There is no real building order in the instructions, just a placement diagram and circuit diagram.
So I used some common sense and started with all the resistors ...

Then adding the caps and some other stuff ...

And finally all connectors, the final transistor and the two ringcores you have to wind yourself.
The final product looks like this, and it took me about 2.5 hours.
The orange wires in the picture are not from one lead, I DO have orange headphones AND a mini paddle with an orange lead ... can you tell orange is my favourite colour ? HI
(I'm still looking for ORANGE 50 Ohm coax ... anyone ?)
Btw, I use the paddle as a straight key by putting it on it's side, there is no keyer chip in this kit.
There is a Chinese kit WITH a keyer for around 15 EURO though.
(search ebay for DIY 51 Super Rock Mite RM Kit CW Transceiver Shortwave Telegraph )

Does it work ?
Yes it does , but ...
The receiver is quite sensitive, but lacks selectivity as you can expect ...
I connected a 40m dipole and connected the phones output to my laptop running the program DSP-FIL by Makoto Mori
This program dates back to 2001 but still does a good job ... all kinds of filters down to 70 Hz.
The only thing you can't do is keying CW and listening to it on the PC .. because of the delay !
So I used my "orange" headphones, these have an extra audio output jack, and this was coupled to the PC. The sidetone of this kit is around 1000 Hz (and not so stable, still have to check which capacitors are responsible for the drift). So I put the DSP-FIL very narrow around 600 Hz, and when keying I heard myself in the headphones, while receiving I listened on the PC. Problem solved.
I called CQ and after 3 times calling , a G station answered and I got a 559 report ... wow !

So I was curious at what power I really had made this QSO with.
My Bird wattmeter is too inaccurate at this level (I only have the 100W element).
So I measured it in the school lab as 820 mW ...
Maybe not too bad, they advertise 2W out, but maybe they mean 2W INPUT , and the circuit values indicate it was designed for 1W  output.

In the mean time I put the PCB in a nice aluminium box, and printed some labels, then put them on the box with clear Scotch tape.

I also added a audio CW filter I had made long time ago, to avoid the use of the PC as a CW-filter.

73 - Luc