[Elecraft] Point me to the note for sending CW when in, SSB mode

[Joe Subich, W4TV]

> None of this MCW drivel has anything to do with the CW scheme for
> SSB transmitters, pioneered if not invented by Collins in their KWM2
> and S-line equipment. It worked for Collins because their mechanical
> filter suppressed the opposite sideband by something like 70-80dB,
> the balanced modulator had good carrier suppression and the filter
> added to that, and they generated a very clean sine wave.

Absolutely - the Collins CW oscillator was nearly test equipment pure.
It was 1 KHz, the mechanical filters had very sharp skirts because of
their low frequency, and the carrier oscillator offset was quite large
it was some 40 dB down the filter skirt to start with.   None of the
Collins rigs had a lot of low frequency (<300 Hz) audio because of the
filter skirts/carrier oscillator placement.

Modern rigs with their wide filters and carrier oscillators well up
the filter skirts just can't produce clean CW from an external
modulating tone - particularly when the tone is nearly a square wave
from over driving the mic preamp.

73,

    ... Joe, W4TV


On 6/15/2013 5:14 PM, Fred Jensen wrote:
> In the marine CW service in the late 50's, nearly all traffic on the
> Holy Wavelength [600m] was MCW.  After all, it was the worldwide
> distress channel.  A lot on working frequencies was too.  Unlike MCW on
> the VHF ham bands, the RF carrier was also keyed, but in either case, it
> was double-sideband amplitude modulation.
>
> Shipboard transmitters usually employed motor-generator sets to get the
> high voltages necessary from the ship's DC mains.  They weren't filtered
> well and most transmitters afloat were modulated by M-G whine.  The M-G
> sets also weren't well regulated so the voltages rose and fell with the
> CW.  The result, if you listened with the BFO on, was a chirping carrier
> modulated by a chirping audio tone with a chirping whine in the
> background.  It was "distinctive" as Ron says but generally less than
> harmonious. :-)
>
> None of this MCW drivel has anything to do with the CW scheme for SSB
> transmitters, pioneered if not invented by Collins in their KWM2 and
> S-line equipment.  It worked for Collins because their mechanical filter
> suppressed the opposite sideband by something like 70-80dB, the balanced
> modulator had good carrier suppression and the filter added to that, and
> they generated a very clean sine wave.
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 2013 Cal QSO Party 5-6 Oct 2013
> - www.cqp.org
>
> On 6/15/2013 10:04 AM, Ron D'Eau Claire wrote:
>> Quite right Vic. A.M. MCW was *required" for any emergency maritime
>> communications. Up until well after WWII, some ships still had crystal
>> detectors as the 'emergency' receiver should the main receiver fail.
>> In any
>> case, A.M. MCW received on a superhet produced a very distinctive
>> sound that
>> made it stand out from other traffic and was required or any shipboard CW
>> transmitter.
>
>
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