Technical stuff

The Techie bits of IRLP Node 6527

ORIGIN

Because of the “experimental” nature of this node, there will most likely be many changes to performance and facilities. As of May 2021 it’s a Linux box on an HP “Thin Client” with a 32GB SSD DOM running an IRLP customised version of Debian 7 “Wheezy” and an IRLP Ver3 board donated by Mike VK8MA. “The Box” started life in Coffs Harbour back in 2002 as a Cyrix P150, 64MB ram and a 2GB hdd, running RH9, using a Ver2.02 board.

Pic of the gear was taken when we had the setup at Lake Macquarie, NSW.

AUDIO

When the node was first set up, all audio was passed directly, however after much experimentation there’s now a fair bit of dynamics processing used on the downlink side, that is, audio coming into the node from the Internet …… we just “happened” to have (drool) a “spare” Aphex Compellor 320A/Dominator-II 720 chain lying around doing nothing much useful, and so for a long time the Dominator part of it was patched in circuit to keep levels consistent, and to “brick wall” limit deviation without generating distortion. Back around 2016, with a critical ear, we determined that this 20+ year old piece of fabulous audio gear possibly needs realignment and who knows what else, and so a spare Behringer Composer MDX2000 is currently doing the honours.

RX/TX

Originally, the Tx, powered by a 100W SM PSU was a good-old Australian designed and made, thermostatically controlled computer power-supply-type fan-cooled Philips FM900. Moving from Coffs Harbour, we stopped for a month or so in South Australia’s Riverland at Barmera and ran the node on the shores of Lake Bonney. Then it was off again, down to Adelaide where we had a location about 200M asl with a view across St Vincent Gulf… coverage was excellent. Then after yet another move around the middle of 2009 (when we relocated from Adelaide, half way across the country to Lake Macquarie) there was 25 watts or so up a short run of nondescript coax to a mag base mounted 5/8ths vertical sitting on the metal roof of the garage at our rented house, virtually at sea level at Rathmines, so not particularly fantastic DX coverage.

As of early 2010 we relocated by about 2 kM to Buttaba. The original setup back in Coffs on the roof of a CBD office building initially had the 5/8ths and later a Butternut collinear antenna array with about 6dB gain donated to the cause by John VK2YLO, and as of the beginning of April 2013 that was dragged out of storage and mounted around 40 M asl. The antenna that is, not John!

Another move interstate at the end of 2014 to S.E. Queensland, just over the Tamborine Mountain range inland from the Gold Coast. Back to the old 5/8ths antenna which stayed on the roof of our Queenslander style house until we copped a direct hit from a wayward lightning discharge in 2020 which blew the daylights out of the 5/8ths loading coil. A couple of weeks later, the Butternut was dusted off and I raised enough courage to climb the roof and erect the big monster!

Another change in 2020 (before the lightning strike) was when Mike VK8MA donated a couple of Motorola GM300’s, one capable of 45W and the other 25W. Naturally the 45W unit was immediately pressed into service, however 2 days after the lightning strike, and just when we thought the radio had survived, even though the antenna had been directly hit and melted, the poor ol GM300 bit the dust too. I’d post the pictures here, but they’d be too horrific for most fans of GM300’s. So now we run the 25 watt unit and it’s going just fine although running hotter than the 45 watt unit ever did. Thank goodness for a big fan !

INTERNET

After starting off with little better than dialup, it’s now 50/25 FTTN through Internode.  Way more than required and shows just how much things have changed over the years.

Naturally, because this is a simplex node, both sides of the conversation may not be audible to a casual listener. There are advantages, but at the expense of (relative to a repeater) limited coverage for the Amateur community at large.

The bloke who owns all this is actually within arms reach of it, most of the time. The learning curve was originally 89 degrees, but it’s been an amazing experience all the same.

John vk4jjw@adnet.com.au
EchoIRLP Node 6527 / 96527 Administrator

Comments are closed.