Pixie CW transceiver

[Geordie_Rob]

Yes a small but rugged system (12v) with extensive range would be highly desirable to myself aswell. My immediate family are spread in a 30 mile or so radius (one of my sisters excluded as she lives in Essex) & knowing I could communicate with them in emergencies (even simple "are you ok?" "Yes all fine here") at pre-arranged times would suffice. I'm sure handheld radios could possibly do it, however it's open broadcast whereas morse code, well how many people nowadays can decipher it? I know I can't.

[Lightspeed]

[Lightspeed]

To get back on track, I proposed the Pixie as a useful prep tool as its inexpensive, small, robust and performs better than its price would suggest. Its also a very simple device with a minimal component count.

That simplicity lends itself to our purpose.

The most vulnerable component in any transmitter is its output transistor. I've taken the precaution of laying in a backup stock of 100 of these. The cost? £1.00 from China.

[Lightspeed]

UPDATE:

I ran a Pixie for a couple of hours this afternoon.

Antenna was a simple low-strung wire, and sound out from the Pixie was plugged into an old laptop running win 3.2 and a morse deciphering software package called CW Skimmer.

twenty stations were logged at ranges from 30km out to 1400km and with fairly regular steps in between. This was achieved using NVIS and single bounce propagation.

At times the software was picking-up 20 odd simultaneous transmissions all in close proximity to the Pixie's fixed 7.023 Megaherz operating frequency.

the only additional kit I used was an antenna matcher which is a physical device to match the antenna's impedance to that required by the Pixie's transmitter output circuit (50ohms). This somewhat reduced the amount of commercial broadcast station bleed-through / interference.

My log for the session is as follows:
PIXIE Log 31 Oct 2015 simple wire antenna
Callsign Location 30km 1400km
oe7gj Austria
oe6rdd Austria
9a2wj Croatia
9a5to Croatia
ok1yr Czech Republic
ok4itga Czech Republic
g4hzv England
dl3rah Germany
dl1dxl Germany
dl4me Germany
dl1bug Germany
dl5ym Germany
dj8sw Germany
df7gg Germany
dl1dgs Germany
dl1rem Germany
dl6lbi Germany
df5lw Germany
dj6tk Germany
hg6lh Hungary
ha5ov Hungary
hg6e Hungary
hg6l Hungary
ha8rc /qrp Hungary (this was a low power 5w station)
iz5cpk Italy
ik5tbi Italy
ly2mm lithuania
pa3cvi Netherlands
pa3dbs Netherlands
pa5wt Netherlands
sp9dba Poland
sp8lep Poland
r4lo Russia
gm3job Scotland
gm4isl Scotland
gm3jks Scotland
yu1ea Serbia
sm0aig Sweden
sm3omo Sweden
m0aig UK

[River Song]

Update 10 November

So my two pixies arrived today. You were quite right LS. One of the so-called 'assembled' came with all the parts 'assembled' in a plastic bag! The other one came fully assembled - Yay!

So next steps -- and it would be useful to get a little crib sheet together Blond Proof.

I obviously need a pair of decent headphones --
Aerial socket --- 20 metre bit of wire or what to plug in
Power - ideally 12v I know but think in terms of start up testing maybe a 9v battery - ideas?
Is there any kind of tuning or is it just a fixed frequency?

Moving on from here - Id like to automate the reception with some of the programs mentioned in earlier posts although I don't use windows 3.2. I would prefer experimenting with Linux apps as I could probably get the full monty up and running on a Raspberry Pi

Cheers

[Lightspeed]

Brilliant Chinese marketing eh.... assembles my ****!

Wire for antenna already covered.

I suggest that first you just listen on the thing to see what you v=can hear.

The antenna connector is what is known as a BNC connector. For listening the length of antenna wire only needs to connect to the centre connector of the socket. Length of antenna wire need only be 12ft or so to start with. This does not need a proper connector. Just push the bare conductor of the wire into the centre connector.

Headphones: ANY Walkman style headphones will do. The socket is wired for stereo three pin plug too. Long term a set of headphones with an inline volume control would be useful. Make sure that you only attache the headphones to the socket marked Phone ( printed on the circuit board)

Power supply: For receiving only, it'll work fine using a PP9 dry cell as a power source. +ve connects to the power socket centre pin. there are a couple of unused through the board connector pads on the reverse side of the board under the power socket. These piggyback the main connector and can be used as attachment points for a pair of wires leading off to the power supply. I am thinking of running a red wire (+ve) and a black wire -ve connected to a pair of choc-block connectors. This will allow any power supply wires to be connected to the radio just by screwing down the contacts in the choc-block, so avoiding the need for a bespoke power connector.

The choc-block connector strategy can be used on the antenna connector too. In both cases you will need use a continuity meter to make sure you know which connector pad is positive and which is negative, and of course 4 spots of solder would be needed too.

[Steve]

Mine has arrived - fully assembled in three plastic bags. Luckily I have 30 years of component level repairs behind me, so I'll be warming up the soldering iron soon.

[Steve]

[Lightspeed]

You're right about that Capacitor Steve, I hadn't noticed it

There are also a couple of sellers showing a board with a component covered with a label marked "remove before washing"!!! WTF?

Yes, my eyes are not up to seeing the component identifications without a magnifying glass either. I also measure component values before installing.

Strangely I have several identical units and the power output is different between each of them, ranging from 0,5w to 1.2w.

[Lightspeed]

Updating this post:

The Pixies I have been testing are doing very well indeed.

Some of the stuff we've done:

Made simple field deployable wire antennas,

Power, sourced good quality connectors with screw driver connectable cables for pp9 or 12v supplies

antenna socket, connectors sourced that allow screwdriver connection so that antenna wire can be replaced in the field

On the last radios built, we've included a morse code key in the aluminium case that house them.

So now we have self-contained robust and quite EMP resilient radios that will accept multiple power sources, and which can be run and maintained by non technical individuals using simple tools from base, or in the field.

Our friends and family network is now pretty solid out to around 60 miles and out to 90 miles using a slightly higher powered model)

Next mods are to add low tech volume control to the headphone socket, and to move the receiver tuning to a normal knob on the front of the box.

We bulk purchased connectors and project boxes, antenna wire etc, and still have quite a lot spare. If anyone needs any PM me.