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Author Topic: MCW Anyone?  (Read 5101 times)
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k4kyv
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Don
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« on: June 03, 2005, 03:57:03 PM »

If the ARRL's bandwidth proposal is adopted into the rules, it would permit a mode that has not been legal on HF for many decades, tone-modulated cw.  As long as the total bandwidth is kept within the legal definition, the mode would no longer be prohibited.

A very simple but effective transmitter could be built using little more than a 100-watt class exciter such as a modern transceiver, a plate transformer and a couple of high power triodes, and associated rf components.  No rectifiers, filter caps, filter chokes or bleeder resistors would be needed for the power supply.  The anodes of the tubes would be fed directly from the high-voltage a.c. plate transformer.

Unlike the old "self-rectifying" raw a.c. rigs of the 1920's, this setup would use the triode tubes as a high power balanced modulator.  Feed rf to the grids in parallel, but use a balanced pushpull plate tank circuit.  The "carrier" would be balanced out, but there would be two "sidebands" 120 hZ apart: USB and LSB at 60 Hz.  This would be basically a double sideband suppressed carrier transmitter tone modulated with 60 Hz a.c.  There would be no raspiness or hash, just two carriers 120~ apart.  The signal would be narrow and clean, and could be copied with a normal CW receiver or with a diode AM detector with no BFO.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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This message was typed using the DVORAK keyboard layout.
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Jack-KA3ZLR-
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« Reply #1 on: June 03, 2005, 05:28:55 PM »

Hi Don,

 There would be nothing illegal about sending CW from a Sound card, feed it into the mic input in SSB and who wud know the difference.
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WD8BIL
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« Reply #2 on: June 03, 2005, 08:27:43 PM »

Then I could actually use the MCW position on the 'ol Scott RCH receiver.

Don.... If you build it I will listen !!

Scott RCH Receiver
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N9NEO
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« Reply #3 on: June 06, 2005, 01:44:15 PM »

interesting, but..

What happens if operator alpha is using one type of cw mode and operator bravo is using another type?  Is the bandwidth that they are using going to be wider? In other words operator bravo hears alpha and zero beats his signal.  Will he be xmit on same freq or is there scenario that he will be 120hz off, or maybe even farther.

regards,
Bob

Just say "NEO"
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k4kyv
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Don
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« Reply #4 on: June 06, 2005, 02:32:02 PM »

Quote from: N9NEO
What happens if operator alpha is using one type of cw mode and operator bravo is using another type?  Is the bandwidth that they are using going to be wider? In other words operator bravo hears alpha and zero beats his signal.  Will he be xmit on same freq or is there scenario that he will be 120hz off, or maybe even farther.


It would be a 50%-50% proposition.  Depends on which of the "sidebands" the other operator zero beats to.  Kind of like a typical AM QSO where none of the stations are exactly zero beat.  But all stations in the QSO should be within 120~ of each other.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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This message was typed using the DVORAK keyboard layout.
http://www.mwbrooks.com/dvorak
AG4YO
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« Reply #5 on: June 10, 2005, 10:57:45 AM »

Best suggestion is to call your ARRL Director and say "no" to the proposed bandplan.  As it evolves it will allow digital signals mixed with voice.  This plan is being pushed by less than 5% of amateurs and will effect 95% of us.  In conversations with Winlink folks and other digital proponents, they view AM as a thing of the past.  Its a shame because AMers are some of the most knowlegable amateurs in the hobby.
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