Saturday, October 20, 2012

Digital modes for a CW transceiver

As I don't know morse code and software decoding of morse seems pretty poor in my experience, I've been looking in to digital modes that could be used with a very simple carrier on/off transmitter.

So far, there are two I've found:

  • Feldhellschreiber - an on/off fax like transmission of letters using 1ms dots
  • CCW - "Coherent CW": an accurately timed version of morse with extra characters supported by MultiPSK. It runs at 12 words per minute and includes a start sequence to allow synchronisation.
  • Any others?
There's an informative thread in the Yahoo? digitalradio group.

CRK-10 Tiny 40m CW Transceiver kit review

Just completed construction of a delightful little CW transceiver from Crkits in China.

This US$52 kit comes with all the surface mount components already in place so construction is easy and low stress.

Just two toroids to wind and then only 10 and 12 turns respectively. The kit went together in a relaxed hour or so (I like to take my time and take breaks to try to avoid hard to unsolder mistakes).

The instructions are very clear, all components were there (in fact I scored one extra trim capacitor and a spare screw - much better than being one down). When it all goes together the metal case looks fantastic and it will make a very solid little unit.

The only glitch I found is that the super clear directions on how to wire J1 and J2 for straight key support are reversed. Oddly this error is in both the instruction manual and the quick guide Rev. B.

I also had a bit of trouble with the push button switch's alignment with the front panel hole, reaming it out a little fixed that easily.

Mine puts out a solid 3W and the receiver sounds good and narrow. On the advice of Stephen, VK2BLQ, I ordered mine for 7030kHz.

Now to learn CW.


Adam has confirmed the error, he wrote: "You are correct about J1 and J2 jumpers. It is a mistake and nobody else told me about it. Probably most of them use paddles so they really don't care too much."

Sunday, October 14, 2012

It's Microsoft vs. Google while Apple runs free

We're on the eve of Microsoft's launch of Windows 8 and their big new push into tablets. I work with some folks who would have been hard core Windows experts a few years ago but I was surprised to hear them chatting enthusiastically about their Android embedded sticks and hackable low cost tablets from Ainol Novo.

Microsoft's delay in competing with Apple in the consumer tablet market has left the door open for Google to gain huge traction amongst windows geeks with their eminently hackable Android tablets. As Google doesn't make money on Android and Microsoft's business is based on making money from Windows Android tablets will always be cheaper and they are sophisticated enough to fascinate the IT crowd.

Meanwhile, Apple is left to capture the mainstream tablet market while the others fight it out for the geeks.

Microsoft has dropped the ball in recent years but they are doing everything right at the moment, it's just that it might be too late to catch up. If corporate IT departments find that their users have Android or Apple tablets and phones they may start to move off Exchange and that will leave Microsoft out of the picture.

Saturday, October 13, 2012

Bargain 12V 32A HP PS-3381-1C1 Power Supply pin out

At the last trash and treasure at Dural I was lucky enough to be steered to a bargain at $10 each. There was a pile of switching power supplies that are known for the low RF noise. HP PS-3381-1C1s.

When you power them up the +12V rail isn't active and a few jumpers are needed to get this going. I found the necessary wiring in a radio control group so I guess these supplies are also used for charging big batteries. Here's the three jumpers to earth I added to get it started:

And here's the 12V out at up to 32A (although I'm not sure my wiring would cope with that for long).

The fan isn't too bad, particularly given the high current capacity. Mine outputs 12.3V but I understand there are modifications for pushing that up to 13.8V to get the most out of some transmitters.