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<p><font face="Arial">Glen,<br>
</font></p>
<p><font face="Arial">Being Brisbane it would have been 25kv, they
never had a 1500V system although that voltage was discussed on
two occasions but never adopted.</font><br>
</p>
Ray vk2tv<br>
<br>
<div class="moz-cite-prefix">On 08/12/17 19:18, Glen English VK1XX
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:67b03aa9-fb9c-371e-3b40-f0ba0a1e264f@pacificmedia.com.au">Ian
was it 1500V overhead, or the now days 25kVAC ?
<br>
<br>
<br>
On 8/12/2017 6:32 PM, Ian Bennett wrote:
<br>
<blockquote type="cite">I remember back in the 80's when I was in
uniform and in Brisbane, a radio vehicle drove over the railway
line near Enoggera with the HF whip still up. Made a BIG flash
(apparently), blew a tyre, shutdown the train network for an
hour or so and welded the 106 to it's mount.
<br>
I have two HF whips mounted on the bullbar of my 100 Series; my
home made APRS antenna is just shy of 2m long (that was the
length of the donor antenna that I dismantled) and is 3150(ish)
mm floor to tip. I haven't had any dramas like the one mentioned
above however I tie them back when negotiating "tight" spaces.
<br>
Will be a different story when we get our truck based motorhome
but I have a cunning plan for that ;-)
<br>
<br>
Ian
<br>
<br>
On 08/12/17 17:39, Mathew McKernan wrote:
<br>
<blockquote type="cite">I did similar with a Codan autotune on
my Landcruiser, mounted above the spare wheel carrier
connected to my Codan 9323.
<br>
<br>
<br>
Hit the line at the same spot... was waiting for smoke to fill
the cabin. I was pleased it didn't, but disappointed as it
would have been pretty impressive!
<br>
<br>
----------------------------------------------------------------------------------------------------
<br>
*From:* OZAPRS <a class="moz-txt-link-rfc2396E" href="mailto:ozaprs-bounces@aprs.net.au"><ozaprs-bounces@aprs.net.au></a> on behalf of
Glen English VK1XX <a class="moz-txt-link-rfc2396E" href="mailto:glenlist@pacificmedia.com.au"><glenlist@pacificmedia.com.au></a>
<br>
*Sent:* Friday, 8 December 2017 5:26:29 PM
<br>
*To:* <a class="moz-txt-link-abbreviated" href="mailto:ozaprs@aprs.net.au">ozaprs@aprs.net.au</a>
<br>
*Subject:* Re: [OZAPRS] On possibilities with short HF whips
<br>
what are the recommendations and user practical limits for
Melbourne ?
<br>
(trams)
<br>
<br>
Canberra here you'll get into trouble ~ 4m
<br>
<br>
I had the loop on my vehicle when I was driving in Melbourne a
fair bit....
<br>
<br>
I once hit a tram line with my car roof antenna heatshrink
insulated
<br>
helical at Racecourse Road, Kensington... it made a huge pop
in the
<br>
receiver but otherwise no damage...
<br>
<br>
<br>
<br>
<br>
On 8/12/2017 3:07 PM, Matthew Cook wrote:
<br>
<blockquote type="cite">This is also worth considering when
looking at larger HF whips.
<br>
<br>
<a class="moz-txt-link-freetext" href="http://www.rms.nsw.gov.au/business-industry/heavy-vehicles/road-access/restricted-access-vehicles/4-6m-high.html">http://www.rms.nsw.gov.au/business-industry/heavy-vehicles/road-access/restricted-access-vehicles/4-6m-high.html</a>
<br>
<br>
Each state has their own variations to the above, nationally
un-restricted is 4.3m.
<br>
<br>
73
<br>
<br>
Matthew
<br>
VK5ZM
<br>
<br>
On 8 December 2017 at 14:03, Graeme <<a class="moz-txt-link-abbreviated" href="mailto:graeme@abrona.com.au">graeme@abrona.com.au</a>
<a class="moz-txt-link-rfc2396E" href="mailto:graeme@abrona.com.au"><mailto:graeme@abrona.com.au></a>> wrote:
<br>
<br>
Thanks Glen.
<br>
<br>
Obviously my decision against buying a 2.2m centre
loaded 40m whip
<br>
because it would bend in the wind to its disadvantage
in favour of
<br>
a base loaded 1.4m whip wasn't a good one for multiple
reasons.
<br>
<br>
Graeme 2HFG
<br>
<br>
-----Original Message----- From: Glen English VK1XX
<br>
Sent: Friday, December 8, 2017 10:19 AM
<br>
To: <a class="moz-txt-link-abbreviated" href="mailto:ozaprs@aprs.net.au">ozaprs@aprs.net.au</a>
<a class="moz-txt-link-rfc2396E" href="mailto:ozaprs@aprs.net.au"><mailto:ozaprs@aprs.net.au></a>
<br>
Subject: Re: [OZAPRS] On possibilities with short HF
whips
<br>
<br>
<br>
Ran some NR predictions for 10 MHz for Brisbane Sydney,
and 7 and 3.5
<br>
<br>
and also some more details calcs on the Diamond 1.4m
logn base
<br>
loaded whip
<br>
<br>
turns out to be ~ 3% efficiency.
<br>
<br>
for the -15dBi TX terminal (1.4m base loaded whip with
suboptimal
<br>
loading Q)
<br>
<br>
yep, in daytime, single hop 750-1200km , 100W into the
antenna,
<br>
expect
<br>
around 15dB SNR for the 300 baud modem given a good
receiver
<br>
antenna and
<br>
setup...with a modem like DireWolf that can cope with
frequency
<br>
variations. Be sure you know your radio frequency
offset before
<br>
you start.
<br>
<br>
with same length whip on 7 MHz, expect about 300-700km
in
<br>
daylight, but
<br>
not much use outside that time and distance.
<br>
<br>
All of this means is for 300 baud FSK packet mode and
100W, the
<br>
mode is
<br>
unsuitable for low efficiency mobile antennas like base
loaded short
<br>
whips. (3% or less efficiency at 10 MHz, 2% at 7 MHz
etc)
<br>
<br>
All this points to: (in my opinion) needing a
>=2.2m long whip
<br>
instead
<br>
of a 1.4m long whip.
<br>
and an antenna with a non base loaded structure (for
300 baud packet)
<br>
<br>
Get your antenna efficiency up to 10% at 7 MHz and then
now you
<br>
have an
<br>
idea setup 24 hours, single freq .... 10 MHz almost
good enough except
<br>
for the wee hours 2am-sunrise when you will be asleep
anyway.
<br>
<br>
So the lesson here, 300 baud packet needs decent
antenna efficiencies
<br>
mobile.
<br>
hence the need for a mode that does about 6dB better
<br>
<br>
sure we can do alot better than 6dB, but 6dB better
mode is what is
<br>
required to work on the 1.4m base loaded whips.
<br>
<br>
Otherwise for 300 baud FSk packet, it needs to be
teamed up with
<br>
antenna
<br>
efficiency >= 8%, implying something with a
feedpoint of around 2
<br>
ohms
<br>
Rr and not too lossy loading and matching... a whip of
2 meters
<br>
tall at
<br>
10 MHz with continuous or 1/3 loaded structure. Base
loaded structures
<br>
are the worst !
<br>
<br>
The longer 1.8m long CB helical whips are a bit hard to
find these
<br>
days.
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
g
<br>
<br>
<br>
On 7/12/2017 6:36 PM, Glen English VK1XX wrote:
<br>
<br>
ok
<br>
<br>
<br>
On 7/12/2017 6:24 PM, <a class="moz-txt-link-abbreviated" href="mailto:vk4tec@tech-software.net">vk4tec@tech-software.net</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:vk4tec@tech-software.net"><mailto:vk4tec@tech-software.net></a> wrote:
<br>
<br>
You are not telling me anything new
<br>
<br>
-----Original Message-----
<br>
From: OZAPRS [<a class="moz-txt-link-freetext" href="mailto:ozaprs-bounces@aprs.net.au">mailto:ozaprs-bounces@aprs.net.au</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:ozaprs-bounces@aprs.net.au"><mailto:ozaprs-bounces@aprs.net.au></a>] On
Behalf Of Glen
<br>
English VK1XX
<br>
Sent: Thursday, 7 December 2017 5:10 PM
<br>
To: <a class="moz-txt-link-abbreviated" href="mailto:ozaprs@aprs.net.au">ozaprs@aprs.net.au</a>
<a class="moz-txt-link-rfc2396E" href="mailto:ozaprs@aprs.net.au"><mailto:ozaprs@aprs.net.au></a>
<br>
Subject: Re: [OZAPRS] Hf gates CD
<br>
<br>
base station 700-1500km away will hear you, but
you wont
<br>
hear a station 50km away.
<br>
<br>
<br>
On 7/12/2017 5:57 PM, <a class="moz-txt-link-abbreviated" href="mailto:vk4tec@tech-software.net">vk4tec@tech-software.net</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:vk4tec@tech-software.net"><mailto:vk4tec@tech-software.net></a> wrote:
<br>
<br>
Go for a walk
<br>
<br>
-----Original Message-----
<br>
From: OZAPRS
[<a class="moz-txt-link-freetext" href="mailto:ozaprs-bounces@aprs.net.au">mailto:ozaprs-bounces@aprs.net.au</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:ozaprs-bounces@aprs.net.au"><mailto:ozaprs-bounces@aprs.net.au></a>]
On Behalf Of Glen
<br>
English VK1XX
<br>
Sent: Thursday, 7 December 2017 4:55 PM
<br>
To: <a class="moz-txt-link-abbreviated" href="mailto:ozaprs@aprs.net.au">ozaprs@aprs.net.au</a>
<a class="moz-txt-link-rfc2396E" href="mailto:ozaprs@aprs.net.au"><mailto:ozaprs@aprs.net.au></a>
<br>
Subject: Re: [OZAPRS] Hf gates CD
<br>
<br>
tracker might well have CD but:
<br>
<br>
1) Consider that in the mobile, you wont
hear any
<br>
stations less than the skip distance
(unless they are
<br>
10km away) . The daytime skip distance
might be
<br>
700km.... so anyone inside that distance
you wont
<br>
hear cause the ionosphere wont support
it..it wont
<br>
support any angles higher than perhaps 45
degrees.
<br>
<br>
The base station though will hear lots of
<br>
transmissions from lots of stations
>700km to 1500km
<br>
away, so there would be significant
collision chance
<br>
if the position update is too often. Maybe
10 minutes
<br>
might be suitable. I dunno why people run..
<br>
<br>
2) With a 5% to 10% efficiency mobile you
wont hear
<br>
too much unless the propagation is
optimal...
<br>
<br>
<br>
glen
<br>
<br>
<br>
<br>
<br>
<br>
On 7/12/2017 5:41 PM,
<a class="moz-txt-link-abbreviated" href="mailto:vk4tec@tech-software.net">vk4tec@tech-software.net</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:vk4tec@tech-software.net"><mailto:vk4tec@tech-software.net></a>
wrote:
<br>
<br>
Blind ?
<br>
<br>
Tracker has CD
<br>
<br>
-----Original Message-----
<br>
From: OZAPRS
[<a class="moz-txt-link-freetext" href="mailto:ozaprs-bounces@aprs.net.au">mailto:ozaprs-bounces@aprs.net.au</a>
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:ozaprs-bounces@aprs.net.au"><mailto:ozaprs-bounces@aprs.net.au></a>] On Behalf Of
<br>
Glen English VK1XX
<br>
Sent: Thursday, 7 December 2017 2:46 PM
<br>
To: <a class="moz-txt-link-abbreviated" href="mailto:ozaprs@aprs.net.au">ozaprs@aprs.net.au</a>
<a class="moz-txt-link-rfc2396E" href="mailto:ozaprs@aprs.net.au"><mailto:ozaprs@aprs.net.au></a>
<br>
Subject: Re: [OZAPRS] Hf gates
<br>
<br>
but how does this matter?
<br>
<br>
You will be transmitting on a
frequency blind
<br>
<br>
there will be receivers you cannot
control
<br>
<br>
There will be any number of propagation
modes you
<br>
cannot control...
<br>
<br>
<br>
<br>
On 7/12/2017 3:34 PM, Andrew Rich
wrote:
<br>
<br>
Hi
<br>
<br>
Can I get a list of hf gates on
10.147
<br>
<br>
In my planning for the Xmas run
<br>
<br>
Cheers
<br>
<br>
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