Thursday, September 24, 2009

DinKey Disappointment

If I take a radio when I go out for a walk, it's usually a VHF handie. That's partly because my wife Olga always comes with me and I think it's more polite to make contacts she can hear than sit with headphones on sending Morse while she twiddles her fingers. But it's also down to all the extra bits and pieces you need to take if you're going to operate QRP HF, like key, ATU, cables and antennas, and the difficulty of actually sending Morse sat on a rock with the radio and key perched on your knee or wherever. There are portable keys available but they are rather expensive. So when I came across the DinKey a few weeks ago I thought it would be a useful and affordable addition to my FT-817 that would encourage me to use it more often out in the field.


Olga collected the DinKey from the Post Office for me yesterday, after paying the £10.72 import tax (about $18) which made it a rather more expensive accessory than it would be for American amateurs. I thought that I would now be regaling my readers with details of my first contacts made using it, but I haven't made any, because I find it almost impossible to send with!

The keyer seemed to be missing dits when they follow dahs within a character, so that "CQ" came out as "KO" or "GO" or sometimes even "MO". I found that the keyer was set to 12wpm so I increased the speed to 16wpm, which is as fast as I can send or receive anyway. That didn't make any difference. Eventually I turned the speed down to 8wpm and I could then send reliably. But that is too slow even for me. The FT-817 batteries would probably be exhausted before the contact was finished!

I spent several hours trying to find the cause of the problem. To cut a long story short I believe that it is because the DinKey uses the FT-817 microphone jack and exploits the option the 817 has to send Morse using the up and down buttons on the microphone. It is not a bad contact or fault in the DinKey per se.

From what I am able to determine by observation, when the FT-817 is busy sending a dah (or a dit) as a result of a closure of one of the mic button contacts it checks for new button closures rather infrequently - perhaps no more than four times a second. This means that when a paddle is closed to send a dit at any normal speed, from 12wpm up, the contact is often closed too briefly for it to be detected. The only way to send reliably is to wait until a dash has been completed before pressing the dot paddle, which results in rather long inter-symbol gaps and rather stilted sounding Morse. When using the microphone buttons it's hard to send very fast anyway because the buttons are quite stiff and any missed dits or dahs would probably be blamed on finger trouble.

Iambic operation is impossible. And although I have never managed to learn true iambic operation - keeping one paddle closed while I briefly close the other to insert a dot into a sequence of dashes or vice versa - clearly my sending style takes advantage of the fact that all electronic keyers support iambic operation which allows me to key slightly ahead of what the radio is sending and let the keyer sort out the spacing. This is not a habit one can easily un-learn, nor do I particularly want to, so I find the DinKey to be just about unusable.

Fred, KF6HQC, the maker of the DinKey, appears to agree with my findings, though he puts it down to "lazy" sending - which I don't agree with - or sending too quickly. He claims that only about 2% of his customers have written to him about this, which I find surprising, though I'm equally surprised that none of the three pages of positive reviews of this product on eHam mention it either.

But perhaps they all send faster than I do. Following Fred's email I tried increasing the speed to 24wpm and found that the DinKey was much more usable because it is harder to key faster than the keyer is sending. The occasional dit was still missed, though.

So it would appear that the DinKey is more or less OK for very proficient CW operators who can send at 24wpm and up (as long as they don't expect iambic operation) but no good for those of us who are only comfortable at slower speeds. I don't send at 24wpm because the keyer runs away from me and adds extra dits and dahs that weren't intended. And I can't receive at that speed anyway. I send slow because that's the speed I want people to come back to me.

Because of what I've had to pay in tax, I shall be out of pocket even if I take up Fred's offer of returning the DinKey for a refund. So I'll keep it and either see if I can use it in another QRP project, rewire it so that it uses the FT-817 mic jack just for support, but plugs into the rear key jack for operation, or wait until I can manage 24wpm - though the latter isn't very likely to happen.
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