NMO - Part 2 - MF CW
Copyright 1994 by Jeffrey Herman
All rights reserved.
Part 2. MF CW at NMO
Sitting adjacent to the HF CW position was a smaller room, enclosed
on three sides in brick painted off-white. The fourth side was
glass, including a sliding glass door, with a small sign glued on
which simply said ``MF CW''. This little booth of modest appearance
was well out of proportion with respect to the role MF CW had played
in the history of maritime communications. Also, though I'm sure not
by accident, the Chief's desk was positioned so he had a direct view
of the MF CW booth. The Chief's position had a compliment of Collins
rcvrs, and one was ALWAYS set on 500kc. More often than not I'd get a
glimpse of the duty Chief listening, with a gleam in his eye, to
the evening traffic on 500.
Upon entering the MF position one was struck with the sight of the
largest 24 hour clock known to mankind. It had the most unusual
red markings on its face. Two red wedges, starting from the center
and flaring outward covered, respectively, minutes :15 to :18, and
minutes :45 to :48; these, of course, were blatant reminder to the
op of the two worldwide silent periods (more one these later). In
addition, each of the twelve five-second intervals around the perimeter
had the first four seconds blocks marked in red with the last second
left white: 4 seconds red, 1 second white, 4 seconds red, 1 second
white, etc., around the entire circumference. Now, these markings
were to aid the 500kc op in manually sending the distress auto alarm:
key down 4 seconds, key up 1 second, key down 4 seconds, key up 1
second, etc., for one minute (more on the auto alarm later).
One's attention would next be drawn to two Collins 651S rcvrs mounted
in the op's console. The top rcvr was locked on 500.000 kc and
the bottom was usually a few hundred cps on either side of
500, say 499.500 kc. This, of course, prevented missing signals
with whom our rcvrs were zero-beated with. The audio from these
two receivers was fed into a 12 tract reel-to-reel tape recorder,
as were all rcvrs and xmtrs at the station; one track was reserved
for WWVH time signals. A second 12 track tape recorder acted as
a back-up to the first. Reels were changed at the beginning of each
new radio day (0000Z).
On a panel next to the two Collins rcvrs was a telephone-type rotary
dial with 4 red lights above it. If digit 1 was dialed, the first
red light would be lit, indicating our MF xmtr was on 500 kc in the
A1 mode; if digit 2 was dialed, the second red light would be lit,
indicating the xmtr was on 500 kc in the A2, or MCW (modulated CW),
mode (more on A2 later); dialing digit 3 shifted the xmtr to 440 kc,
in A1, where 440 kc was NMO's working frequency; dialing digit 4
shifted the xmtr to 512 kc, A1 (more on 512 later).
I'm not sure if this was against FCC or ITU regulations, but our 500kc
xmtr was ALWAYS set to the A2/MCW mode when I was at the key; I hope
there is a statute of limitations concerning this possible violation!
I loved the musical notes A2 produced.
Note that our transmitter site was at least 5 miles away, on the
4000 ft peak of the Koolau Mountains. Thus we enjoyed full duplex
At a right angle to the op's desk was a typewriter containing the
MF CW radio log. During radioman school we were instructed to
attempt to log every signal were heard on 500 (an impossible feat),
but at worst, make an entry every 5 minutes (ITU regs!). If no
signals were heard within a 5 minute period (which would never
happen at night) then one would enter:
NO SIGS 500 2308Z
NO SIGS 500 2313Z
BEGIN SILENT PERIOD 500 2315Z
END SILENT PERIOD 500 2318Z
KPH KPH KPH DE WNKL WNKL AMVER 425 K / WNKL DE
KPH R UP / UP / EE / EE 500 2320Z
NO SIGS 500 2325Z
Thus, what ever we heard would be typed directly into the log.
At a right angle to the log typewriter was a second typewriter
which was used to copy traffic from ships to NMO: OBS, AMVERS
Dead Head Medicos (medical reports handled free-of-charge),
and other non-commercial traffic. By U.S. law, Coast Guard
stations cannot handle commercial traffic, for that would take
revenue away from the commercial stations.
Sitting on the ops desk was a Vibroplex chrome-plated bug, and
a cheap straight key screwed onto a thin sheet of plexiglass.
I, of course, only used the straight key.
Shifts at NMO ran like this:
12 hours on
12 hours off
12 hours on
72 hours off.
The day watch started at 0700 and ended at 1900 (local); night watch
ran from 1900 to 0700 the next morning
During my off hours I rebuilt an older wooden sailboat that doubled
as my home; that enabled me to collect money from the CG for off-base
housing... What a life, huh?
No one on my shift had any particular love for the 500 position (``what
fools!'' I thought), so, even though we were supposed to rotate positions
every 3 hours, I volunteered to remain at the 500 position for the full
12 hours shift (especially during the night watches); I loved it!
It was from this modest console that I would spend the next three years of
my life. The things that I copied would, at times, amaze me, cause me
laugh so hard I would fall out of my chair, or cause me to break down
weeping. To this day I cannot forget the ship's op whom I was working a
distress with - how he stayed at his key while his ship broke up in heavy
seas - how his transmitter emitted a scream at the moment the ocean flooded
his radio room shorting the batteries and radios...
End of Part 2.
Jeff KH2PZ / KH6