[CW] DDD SOS DDD from GLD

[D.J.J. Ring, Jr.]

Modulated CW with a steady carrier is A2H with two sidebands.  It was never
used except for direction finding transmissions from land or ocean station
ships. Life Boat radios used A2A MCW on 500 and 8364 both keyed on and off
by automatic or manual keying.

A3 is full carrier radiotelephony as used on medium wave AM broadcast band,
shortwave and longwave.

Spark is damped waves, Mode B. Still legal for distress.   In marine use it
was mostly gone by early 1950s, last heard in some backwaters.  New Zealand
had an inter-island steamer using spark in the late 1960s.



On Fri, Dec 21, 2018, 21:08 Richard Knoppow <1oldlens1 at ix.netcom.com wrote:

>     A2 or A3 was used for distress traffic on 500Khz because
> there were numerous crystal emergency receivers in use. All the
> autoalarms responded to tone telegraphy, anything from about
> 400Hz to 1 Khz, they did not respond to CW.
>     The RCA station in Los Angeles, KSE, used A2 when making
> calls on 500Khz. Evidently, the oscillator was keyed when the
> transmitter went on the air because the tone faded in after a
> couple of seconds, sounded like the filaments were warming up.
>     A2 is where a modulated carrier is keyed, A3 where the tone
> is keyed on a steady carrier.  All this is a carry over from the
> days of spark (Class B) which is sort of modulated, sounds like a
> buzzer. Description meant for others, I know you know this stuff
> Dave.
>
> On 12/21/2018 5:57 PM, D.J.J. Ring, Jr. wrote:
> > I thought some would like to hear a recording of Land's End
> > Radio/GLD involved in a SOS sending DDD SOS DDD (SOS Relay) messages.
> >
> > Finbar EI0CF (retired from Malin Head Radio/EJM) posted a DDD SOS
> > DDD from Lands End Radio/GLD.
> >
> > Beautifully done.
> >
> > I thought people would like a listen:
> >
> https://archive.org/details/MalinHeadRadioEjm-The500KhzRecordingsOfFinbarOconnorEi0cf/RegSosGLD080394Mod1.mp3
> >
> > More here:
> >
> https://archive.org/details/MalinHeadRadioEjm-The500KhzRecordingsOfFinbarOconnorEi0cf
> >
> >
> > Lands End Radio/GLD appears to switch from A1A CW emission to
> > modulated to A2A Modulated Continuous Wave (MCW)  right after SAG
> > Gothenburg Radio, Sweden makes an TTT (Navigation Warning) for
> > DECCA malfunction, etc.  Notice the change in tone and how much
> > easier it is to copy. There are three "tones" on a MCW signal
> > with BFO reception, lower side band, carrier and upper side band,
> > at least one tone usually gets through the 500 kHz interference.
> >
> > 73
> > DR
> >
> >
> >
> >
> > 73
> >
> > DR
>
>
> --
> Richard Knoppow
> 1oldlens1 at ix.netcom.com
> WB6KBL
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