[CW] Ship Radio Room clock
Richard Knoppow
1oldlens1 at ix.netcom.com
Mon Jan 10 17:02:19 EST 2022
Probably the same mechanism but I suspect a deck clock, not a
radio room clock because it doesn't have either the silent period
markings or the extra hour hand. Radio room clocks have a second
hour hand which can be set without resetting the clock. The clock
is set for UTC (GMT) and the extra hand set for local time where
the ship is. The older clocks are marked with the silent periods
for 500Khz watches and also for the intervals for hand keying an
auto-alarm signal. Some later clocks have markings for watches on
2182 Khz, in Green rather than red.
I don't know all the manufacturers who made marine clocks
around the ww-2 period but Chelsea and Seth-Thomas had contracts
and were large clock makers. I am sure there were some others.
Presumably, the specs for these clocks exist somewhere.
There were also clocks with 24 hour dials but not radio room
clocks.
I don't know when the clocks with the 500Khz watch markings
originated but old pictures of ship's radio rooms do not show
them even though the silent periods were required from perhaps as
early as the 1912 regulations.
For those not familiar with this all ships and coastal
stations were required to maintain radio silence and to also
maintain a listening watch on 500Khz, the international distress
frequency, twice an hour for three minutes beginning at 15 and 45
minutes past each hour. The radio silence applied to 500Khz only
and stations could continue to use other frequencies provided
they did not interfere with 500Khz.
A second distress frequency was later added 2182Khz for voice
communication but I think this was fairly late.
Oh, another note (showing off), the Auto-Alarm was a device
to provide a watch on 500Khz on ships without enough operators to
maintain it. It was a fixed tuned receiver at 500Khz which
listened for a signal consisting of a series of dashes. These
were four seconds long and separated by one second, a total of 12
dashes were sent in one minute. Transmission on 500Khz was
modulated so some auto-alarms responded only to MCW, typically
around 1Khz. The receiver contained a timing circuit, in some a
system of mechanical relays and in others an electronic timer
with tubes. If the alarm got four or five dashes sequentially it
would ring bells and light lights in the radio room, the
operator's cabin and the bridge. The operator could then listen
for an SOS. In many ships the auto-alarm signal was keyed by hand
using the radio room clock as a guide. David Ring's recording of
his distress traffic I think begins with an auto-alarm signal.
I believe the British built the first auto-alarms, when they
were adopted by international regulation most American ships had
alarms made by either RCA or Federal Radio. These did the same
job but were of different designs.
Probably none of this is new to members of this list but
perhaps is interesting to some.
On 1/9/2022 9:58 PM, D.J.J. Ring, Jr. wrote:
> Chelsea made clocks with U.S. Maritime Commission also.
>
> 1.jpg
> 73
> DR
>
>
> ______________________________________________________________
> CW mailing list
> Home: http://mailman.qth.net/mailman/listinfo/cw
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:CW at mailman.qth.net
> CW List ARCHIVES: http://mailman.qth.net/pipermail/cw/
> Unsubcribe send email to
> cw-unsubscribe at mailman.qth.net
> Subscribe send email to cw-subscribe at mailman.qth.net
> Support this email list: http://www.qsl.net/donate.html
>
> =30=
--
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
More information about the CW
mailing list