Andrew, NV1B, wrote:
This sounds interesting. I've never heard much about it. Are high speed CW
ops using this in lieu of "the real thing" to get around rigs' limitations?
Since it's on SSB, I assume it's not legal down in the conventional CW
portion of the band. It sounds like it could be an easy way for QRQ CW to
operate from any rig in the 70 to 100 range, or so.
------------------
It's legal CW even though it's generated in SSB mode since only the single
frequency is transmitted, but I doubt if real HSCW be welcome (or legal) on
the HF CW bands because of the bandwidth. A CW signal, like any signal, has
sidebands that occupy a bandwidth directly proportional to the data rate. If
a CW signal is received on a too-narrow filter, the keying is lost: either
the signal appears as steady noise or a steady tone ('ultimate' filter
ringing!). For a normal CW transmission at some tens of WPM the bandwidth
needed is very small - only in the tens of Hz or less. HSCW at hundreds of
words per minute can require hundreds of Hz of bandwidth. That is on a
receiver using conventional CW filters it'd be heard as a strange tone with
very noisy, wide sidebands extending a long way on both sides of the carrier
frequency! The keying may not be at all evident.
But for something in the middle, >50 WPM and up, keying a tone into the mic
jack in SSB mode may be the way to go to avoid the shaping built into the
rig. The K2 lets you define the receive filters separately from the transmit
filter in SSB, so you can still have the flexibility of the K2's selectable
receive CW filters while transmitting using a keyed tone in SSB mode. If you
get really interested in pursuing it after you build your K2, jump on here
or contact elecraft directly. Wayne, the principal designer for the K2, is
always interested in new mods and uses for the rig and he's quick to offer
help and advice. There are a number of very talented and experienced
engineers on the reflector here who have contributed greatly to the
development of improvements for the K2 over the years who may be able to
offer their help as well. The support you get is one of the most valuable
benefits of owning an Elecraft rig.
The only possible issue I can think of is that in SSB mode, the frequency
display is the carrier frequency. So, if you tuned it up on 7030.00 kHz and
used a 500 Hz tone to key the rig, the actual transmit frequency would be
500 Hz above or below the displayed xmit frequency - that is either 7029.05
or 7030.05 kHz, depending upon which sideband you are using. The K2 has RIT
and full SPLIT operation, so you can adjust the receiver tuning
independently of the transmit frequency, so that shouldn't be a serious
issue.
I am certain that McElroy's record is for solid hard copy. That was back in
the days when a human being was an essential part of a manual "RTTY" or
"TOR" system designed for precise hard copy. The human's job was to convert
the sounds in the phones into precise strokes on the keys to make the right
letters! "Head copy" was not considered a very useful achievement.
It'd be interesting to see verifiable demonstrations of the sort of speeds
that are being achieved without hard copy.
Ron AC7AC
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