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 November 2015 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 a slightly modded IRLP Ver 2.02 board (we fitted an “Aux 1” switch for use with Dave’s CW id-er). “The Box” started life back in 2002 as a Cyrix P150, 64MB ram and a 2GB hdd, running RH9.

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. Recently, 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

The Tx, powered by a 100W SM PSU is a good-old Australian designed and made, thermostatically controlled computer power-supply-type fan-cooled Philips FM900 and from around the middle of 2009 (when we relocated from Adelaide, half way across the country to Lake Macquarie) was shoving 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 gear has changed a bit since back in the Adelaide days, however with a location about 200M ASL the coverage there was rather good! The original setup back in Coffs on the roof of the CBD office building had a Butternut collinear antenna array with about 6dB gain, and as of the beginning of April 2013 that was dragged out of storage and mounted around 40 M asl.

Another move interstate at the end of 2014 to S.E. Queensland, just over the range from the Gold Coast. Back to the old 5/8ths antenna until we can pluck up the courage to climb the roof of our Queenslander style house and erect the Butternut!

INTERNET

Currently ADSL through Internode. On a RIM, so can’t do any better than 8Mbit (way more than enough for a node), however it’s just spectacular compared to the 3G wireless thing we were stuck with for the first 11 months or so.

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@wia.org.au
EchoIRLP Node 6527 / 96527 Administrator

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