[OZAPRS] Concerned about 10.151Hhz LSB

[Chris Hill]

Hi All,
 
My personal thoughts on operating on 10.151 MHz LSB :  "Don't do it!"
 
Instead, operate on 10.14x MHz USB...  it still means you will be
operating on the correct actual "tone" frequencies, and AX.25 packet's
NRZI encoding does NOT care whether the tones are sent USB or LSB...  just
the transitions are important.
 
Recipe for HF APRS happiness;
1.  Look up the specs on required spectral purity for out of band
transmissions (varies from one country to another, but at least -40dB or
better)
2.  Estimate (or measure) the Signal to Noise ratio of the audio you are
feeding from your TNC into your HF rig.  Don't forget to add power supply
noise, alternator whine, keying spurii from the modem chip, etc etc
3.  Say "Oh Oh!"
4.  Change from LSB to USB
5.  Change dial frequency from 10.151 MHz to 10.1481 MHz
6.  Smile - you're now on the international HF APRS frequency!  (Legally).
 
73 Chris vk6kch
 
 
 

-----Original Message-----
From: ozaprs-bounces at marconi.ics.mq.edu.au
[mailto:ozaprs-bounces at marconi.ics.mq.edu.au]On Behalf Of Brian Beamish
Sent: Tuesday, 2 December 2003 7:53 PM
To: OZAPRS
Subject: [OZAPRS] Concerned about 10.151Hhz LSB



Hi Folks

I understand that there is a push to change the 30mtr APRS frequency to
the international frequency of 10.151Mhz LSB.   

This is of concern to me as I personally feel that it may bring
unnecessary attention to us as anyone using a modern transceiver on that
frequency would be announcing to the department that they had modified
their transceiver to do so.

I just tried to transmit there on my FT-897 and found the highest that I
could get was 10.150Mhz and nothing more to operate on 10.151Mhz I would
have to modify the transceiver.

I personally would far prefer we stay where we are why even the
International frequency has had to go to and perhaps beyond the extreme
edge of the band has me beat.

I agree on the tones for example using the Tigertronics TM-1 with the
IC-706 in the car to net to them I am on 10.148 as the TM-1 tones differ
from those used by both VK4DMI and VK3MY both of whom are on 10.149Mhz.

Now just as an example if we were to reverse the situation and VK4BBS was
the HF Gateway on 10.151Mhz and both VK3MY and VK4DMI were mobiles all
using the same gear that they are now both mobiles would have to be on
10.152Mhz to net with VK4BBS.

My personal opinion and recommendation is that we stick to where we are
now 10.149 LSB.

B C N U

Brian VK4BBS

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