 | Amateur radio club ETGDPI4THT | Faculty for Electrical Engineering, Mathematics and Computer Science | ||||
Yesterday evening we finally installed the antenna, andthe WebSDR server is now finally operational again!In the end, we were offline for 1 year, 8 months and 5 days.We'll still have to see how well the new antenna performs.
For now, the system has been configured for 8 bands of each 600 kHz wide.In future, we intend to install a system with continuous coveragelike the experimental system that has been active from my (PA3FWM's)home.
Update May 25:
We have obtained permission to mount the antenna semi-permanently atthe place where we successfully tested it earlier (see below).However, in the discussions with people from the university's facilityservices about this, it turned out that our planned mounting point wasnot yet properly grounded for lightning protection, which is needed whenwe attach an antenna there. They have ordered proper lightning protectionto be installed; when that's done, we can mount the antenna.
Update April 19:
New tests done, after designing and building a low-pass filter for the Mini-Whip.The resulting waterfall displays can be seen here.
Clearly, the noise around 7 MHz is gone now, so thas was probably indeedcaused by overload due to FM broadcast transmitters.The band now looks quite clean, with lots of amateur signals visible andaudible.
Unfortunately, there's a lot of QRM on 80m, of which the cause is unknown.
Next step: mounting this antenna in a (semi-)permanent way.
Update April 5:
Some more testing done, with the Mini-Whip again temporarily installedbut this time in an (almost) watertight enclosure and on a little pole.See here for a picture of the waterfalldisplays.
The noise level jumps back and forth between two levels, mostlynotable on 80m, 40m and 30m bands. We later found that this variationwas due to a flaky ground connection;with the ground connection solidly attached, the noise is low.
There's some broadband noise covering the low end of 40m.This may well be an intermodulation product of two nearby FM broadcasttransmitters on 93.7 and 100.7 MHz; if so, then a simple low-pass filterat the input of the active antenna should solve this.
All across 80m the noise also seems high; the cause of this is as yetunknown.
The waterfall at the bottom shows a frequency range near 27 MHz;the very strong signal here is a pager transmitter (for the university'ssafety personnel) located on the same building as we are. Fortunately,it looks like it doesn't overload the active antenna, because there'sno correlation visible between its transmissions and the noise levelin the other bands.
Because the antenna was mounted in a very provisional way, we couldn'tleave it running. But we're slowly getting there... :-)
Update 29 March 2012:
Tonight (we usually work on this on our club evening on Thursday)we profited from the evening light (due to spring days and daylightsaving time), to semi-permanently install a cable to the plannedantenna location on the roof.
Some people asked what kind of active antenna we're experimentingwith: the most promising one so far is a PA0RDT Mini-Whip.
To be continued...
Update 8 March 2012:
Some more tests done, with the active antennas now placed at adifferent location on the roof and with better grounding.The results were a lot better and quite encouraging, although not perfect yet.To be continued...
Update 23 February 2012:
We did tests with two active antennas. Unfortunately, the noise levelthey received was way too high: only the strongest broadcast signalswere audible.Since the top part of the building is all metal, I don't think so muchnoise can leak out of the building. More likely, either both activeantennas are broken, or they picked up this noise due insufficient grounding.To be continued...
Update 14 February 2012:
We made another step forward: we got a key with which we can open the doorthat gives us access to the roof, so we can now physically go to the otherside of our hole in the wall, and thus actually do something with cablesthat we feed through the hole...
Update 25 November 2011:
Yes!Yesterday, the hole in our wall was installed, as demonstrated by thebelow picture, showing some daylight coming in through the pipe through the wall.It's not so clear in this picture, but the pipe is more than 25 cm long, and finishes onthe outside with a 45 degree bend downwards, to keep rainwater out.
Next challenge is to mount some temporary antenna on the outside...
Update 17 November:
Finally good news: we've been told that next week the hole in thewall will be made for us!
We won't be able to install our big masts and beam antennas (for theclub's use) yet, but a wire or active whip for the WebSDR should bepossible soon!
Update 1 September:
By popular request, here's an update:
Unfortunately, there is still no real progress, but based on regularcommunication with several people in the faculty, we have good reasonto believe that in the end we will get antenna facilities; it just takesmuch longer than I even imagined...
Update 28 February:
Don't despair, we still intend to bring our receiver online again,but the antenna cable feedthrough still has not been installed.However, we did recently hear that a list is being made of all theminor changes that still need to be made to the building, and thatour antenna facilities are also on that list.
Update 4 January:
Happy new year everyone!
Unfortunately, there's no news yet about our antenna connection.
Thanks for all the mails I got, expressing support and/or with tipson how to feed an antenna signal through a window that cannot be opened.Unfortunately, those tips are not usable: our only window is to thecorridor, not to the outside. That is because our club room is in apart of the building that originally was only meant for storage, sono outside windows were installed.
Update 16 December 2010:
It looks like it will take a while more before we can install an outside antenna.Today I've done a preliminary experiment with an indoor antenna, but thatwas not yet successful.
Several people have e-mailed me with the suggestion to use a flat cable feed-throughfor windows.Unfortunately, our new room does not have a suitable window for that.
Update 26 November 2010:
We're back -- well, somewhat.
Over the past couple of weeks, we have moved all our stuff to our new club room (although much of it stillhas to be unpacked),and since yesterday, we have an internet connection there.
Unfortunately though, we do not yet have any possibilities for feeding an antenna cable through the wall.It is also still very unclear how long it will take until it this will be arranged.
Background:
Since Wednesday November 3 (2010), this WebSDR receiver has been offline.This is because the radio club at the University of Twente, where this receiver is hosted,had to move to a new building, along with the entire department of electrical engineering.We knew this was coming and we were busy preparing the move (dismantling our antennas,packing our equipment, etc.).On October 29 we were told that we had to empty the old room by November 4, which is earlierthan we expected. That's why we could not announce this more in advance, and could notmake the transition smooth by first preparing the new room.
73, Pieter-Tjerk, PA3FWM (e-mail about this topic: qrt AT websdr.org)
