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LF: 2 Hz shift DFCW

To: [email protected]
Subject: LF: 2 Hz shift DFCW
From: "Vernall" <[email protected]>
Date: Thu, 31 May 2001 09:32:00 +1200
References: <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
Hi all,

One way of generating a frequency for LF transmitting is to "divide by 100"
from an HF band.  In New Zealand we work around 181.4 kHz, which
conveniently means 100 times turns up within the 17 metre amateur band
18.068 - 18.168 MHz, so there is no issue with defeating the "transmit
inhibit" as the frequency is not outside a recognised ham band.

Anyway, the point of this bulletin is to draw attention to the FSK or RTTY
facilities on modern rigs, whereby applying TTL drive can provide 200 Hz FSK
for HF packet or PACTOR.  After dividing by 100, that gives 2 Hz shift at
LF, which is quite suitable for long dot length DFCW.  Other frequency
shifts can likely also be set, such as 170 Hz, but 200 Hz is the "nice
number offset".

Even for the EU 136 kHz band, an amateur transceiver tuned around 13.6 kHz,
divided by 100, could produce a 2 Hz shift at 136 kHz, using the available
FSK functions of the HF rig (but also dealing with transmit inhibit for
frequencies outside an amateur band).

This appears to be a convenient way of generating DFCW at LF with a minimum
of rig surgery.

73, Bob ZL2CA

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