History tidbit

Jeffrey Herman jeffreyh at HAWAII.EDU
Thu Nov 6 22:25:39 EST 1997

While on my way to the QA's (mathematics research texts in the
library) I always find myself somehow taking a detour through
the VK's (maritime radio) (how does that happen?). Anyway,
I stumbled across a gem: 1944 edition of "Marine Radio Manual"
(wartime edition).

There are goodies in here I've never seen before ("How to test
your Mackay and RMCA Auto Alarm receivers"). But here's a *real*
curious item: From the FCC/ITU regulations:
"CRYSTAL RECTIFIER. Whenever a vessel is subject to the Safety Con-
vention, the radio installation, in addition to all other requirements,
shall be provided with a radio receiver capable of receiving radio-
telegraphy signals, A2 and B emissions, on all frequencies within
the band 350 to 515 kcs by means of a crystal rectifier, and for this
purpose such receiver shall not require the use of electron tube(s).
The crystal rectifier may be included in the main receiver, in the
emergency receiver, or an additional receiver having this facility
may be provided which shall be located as near the emergency operating
position as is practicable."

First, don't be surprised to see the B-emission requirement, for
it wasn't until *1965* that spark was finally outlawed on 500 kc
for all (including distress) communications (see Schroeder's
"Contact At Sea"). But my goodness, requiring a tubeless crystal
rectifier onboard as late as 1944?

Has anyone ever seen such a commercially-made rcvr for that band
(350-515 kcs)?

Stay tuned for more tidbits.

Jeff KH2PZ / KH6 (student of maritime wireless)

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