The military clocks didn’t come “out of the box” with silent periods marked, but many (most?) Navy shacks would have them marked, typically with red grease pencil on the glass.

We (combatants) always kept a listening watch on 500KC, 8364KC, and 121.5MC if steaming independently but never transmitted there, so effectively we “observed silent period” on a continuous basis.  An LF transmitter might be kept in readiness if available.  If steaming in a battle group, convoy guard, or other organized formation, the OTC would designate guardships for those frequencies.

I should point out that “silent period” applied to 500KC, not to working frequencies, of which we might have several simultaneously in use, depending on the tactical situation.  A large combatant, like an aircraft carrier or other flagship, would have dozens of different circuits active simultaneously, but only observe “silent period” on 500KC.  8364 and 121.5 were always on “silent period”, completely reserved for emergency traffic.

73, de Hans, KØHB
“Just a Boy and his Radio”™
From: [email protected] <[email protected]>
Sent: Sunday, January 9, 2022 11:16 AM
To: [email protected]; CW Reflector
Subject: Re: [CW] Ship Radio Room clock
 
So here's a dumb question.  My clock has silent periods marked Hans but yours doesn't.  Did military ships not have to observe silent periods ?  And do you think the one I posted a picture of is perhaps from a merchant marine ship ?
I love the history but I don't know it all ...yet.  
Oh and I have a Bureau of Ships Navy comparing watch (Hamilton 2974) that has an early serial #.  #23 made in 1940/1.     Jim N5KY


On Sun, Jan 9, 2022 at 9:31 AM, Hans Brakob
Someone asked “Why 24 hour format?”

Answer: Because it was always ZULU-time in the radio shack.

73, de Hans, KØHB
“Just a Boy and his Radio”™
Master Chief Radioman, US Navy (Ret)
From: [email protected] <[email protected]> on behalf of abqcooks--- via CW <[email protected]>
Sent: Sunday, January 9, 2022 10:05:56 AM
To: CW Reflector <[email protected]>
Subject: [CW] Ship Radio Room clock
 
Greetings Gents,
Here's a photo of a wall clock I have in the shack. Supposedly it dates to WW2 and was on a Navy ship.  Since there's been chatter about coastal stations and such I thought I would post this photo. Note it's marked Mackay Radio. Any old timers seen a clock like this ??


  Jim N5KY