<div dir="ltr">This is also worth considering when looking at larger HF whips.<div><br></div><div><a 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></div><div><br></div><div>Each state has their own variations to the above, nationally un-restricted is 4.3m.</div><div><br></div><div>73</div><div><br></div><div>Matthew</div><div>VK5ZM</div></div><div class="gmail_extra"><br><div class="gmail_quote">On 8 December 2017 at 14:03, Graeme <span dir="ltr"><<a href="mailto:graeme@abrona.com.au" target="_blank">graeme@abrona.com.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Thanks Glen.<br>
<br>
Obviously my decision against buying a 2.2m centre loaded 40m whip because it would bend in the wind to its disadvantage in favour of 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 href="mailto:ozaprs@aprs.net.au" target="_blank">ozaprs@aprs.net.au</a><br>
Subject: Re: [OZAPRS] On possibilities with short HF whips<div class="HOEnZb"><div class="h5"><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 loaded whip<br>
<br>
turns out to be ~ 3% efficiency.<br>
<br>
for the -15dBi TX terminal (1.4m base loaded whip with suboptimal loading Q)<br>
<br>
yep, in daytime, single hop 750-1200km , 100W into the antenna, expect<br>
around 15dB SNR for the 300 baud modem given a good receiver 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 you start.<br>
<br>
with same length whip on 7 MHz, expect about 300-700km in 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 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 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 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 antenna<br>
efficiency >= 8%, implying something with a feedpoint of around 2 ohms<br>
Rr and not too lossy loading and matching... a whip of 2 meters 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 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>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
ok<br>
<br>
<br>
On 7/12/2017 6:24 PM, <a href="mailto:vk4tec@tech-software.net" target="_blank">vk4tec@tech-software.net</a> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
You are not telling me anything new<br>
<br>
-----Original Message-----<br>
From: OZAPRS [mailto:<a href="mailto:ozaprs-bounces@aprs.net.au" target="_blank">ozaprs-bounces@aprs.ne<wbr>t.au</a>] On Behalf Of Glen English VK1XX<br>
Sent: Thursday, 7 December 2017 5:10 PM<br>
To: <a href="mailto:ozaprs@aprs.net.au" target="_blank">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 hear a station 50km away.<br>
<br>
<br>
On 7/12/2017 5:57 PM, <a href="mailto:vk4tec@tech-software.net" target="_blank">vk4tec@tech-software.net</a> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Go for a walk<br>
<br>
-----Original Message-----<br>
From: OZAPRS [mailto:<a href="mailto:ozaprs-bounces@aprs.net.au" target="_blank">ozaprs-bounces@aprs.ne<wbr>t.au</a>] On Behalf Of Glen English VK1XX<br>
Sent: Thursday, 7 December 2017 4:55 PM<br>
To: <a href="mailto:ozaprs@aprs.net.au" target="_blank">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 stations less than the skip distance (unless they are 10km away) . The daytime skip distance might be 700km.... so anyone inside that distance you wont hear cause the ionosphere wont support it..it wont support any angles higher than perhaps 45 degrees.<br>
<br>
The base station though will hear lots of transmissions from lots of stations >700km to 1500km away, so there would be significant collision chance if the position update is too often. Maybe 10 minutes might be suitable. I dunno why people run..<br>
<br>
2) With a 5% to 10% efficiency mobile you wont hear 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 href="mailto:vk4tec@tech-software.net" target="_blank">vk4tec@tech-software.net</a> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Blind ?<br>
<br>
Tracker has CD<br>
<br>
-----Original Message-----<br>
From: OZAPRS [mailto:<a href="mailto:ozaprs-bounces@aprs.net.au" target="_blank">ozaprs-bounces@aprs.ne<wbr>t.au</a>] On Behalf Of Glen English VK1XX<br>
Sent: Thursday, 7 December 2017 2:46 PM<br>
To: <a href="mailto:ozaprs@aprs.net.au" target="_blank">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 cannot control...<br>
<br>
<br>
<br>
On 7/12/2017 3:34 PM, Andrew Rich wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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>
</blockquote>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a><br>
<br>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a><br>
</blockquote>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a><br>
<br>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a><br>
</blockquote>
<br>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a><br>
<br>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a><br>
</blockquote>
<br>
<br>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a><br>
</blockquote>
<br>
<br>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a> <br>
______________________________<wbr>_________________<br>
OZAPRS mailing list<br>
<a href="mailto:OZAPRS@aprs.net.au" target="_blank">OZAPRS@aprs.net.au</a><br>
<a href="http://lists.aprs.net.au/mailman/listinfo/ozaprs" rel="noreferrer" target="_blank">http://lists.aprs.net.au/mailm<wbr>an/listinfo/ozaprs</a><br>
</div></div></blockquote></div><br></div>