Re Marconitrainingrecords Re Maritime Spark Transmitter So

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In a message dated 02/03/2003 1:16:09 AM Eastern Standard Time, 
[email address removed] writes:

> 
>  Many thanks.
>  
>  
>  
>  73, Ric, VK7RO
>  
I checked the 78 rpm practice records.  

The "Marconi-Victor Wireless Telegraph Series":

"104-A  Lesson No. 7  Press Messages with Static Interference"
This is a buzzer with occasional "thunder" consisting of the conventional 
sound effect of banging a piece of sheet metal.

"105-A  Lesson No. 9  Press with Interference from Other Stations"
This is just two buzzers with slightly different tones.  The buzzers sound 
like the "doorbell" type (low raspy pitch) rather than the high pitched ones 
used on some code practice sets.

The "Marconi Official Training Signals" sides:

Cat. No. B 630 (9512)  y19867 Press and Press Jambing
Cat. No. B 630 (9513)  y19868 Messages and Press Jamling (sic)

use higher pitched buzzers and sound more realistic (and much faster) but 
still with only two tones and no background static except that from the 
shellac records themselves (which is plenty).

Since these discs are from the acoustic era, it is most likely that the 
recordings are of the sound of the buzzers, with no electrical signal, let 
alone RF, involved at all.

Mike Csontos