Header

Satellite Antennas Built And Tested

March 25th, 2011 | Posted by Gavin, M1BXF in General - (1 Comments)

Following on from the previous satellite antenna posts here is an update on what happened after the antennas were received. At first I wanted to build cross yagis for 2m and 70cm as the HyGain ones I had previously seemed rather poor in terms of performance. I hunted the web for some designs and couldn’t find anything – I then thought I’d look for simple non crossed yagi designs which had boom lengths around 2m then modifying it to be crossed but again it was hard to find anything decent. As the antennas will be used on the Arran DX’pedition I also had reservations about using a design not specifically based around a cross yagi or built for the satellite portion of the band.

I then looked at the UK retailers to purchase satellite antennas and again nothing which met my requirements!

Thankfully I bumped into previous dx’peditioner Geoff DDX one morning on the local Cambridge CRG repeater GB3PY who told me Brian G6HFS had recently purchased some and I should speak with him, well a phonecall to Brian and I was on the Wimo website, Wimo are predominantly an antenna and antenna systems company in Germany http://www.wimo.com/.

 Bild Logo

Having a look on their site I found exactly what I needed! Pretty much the same as what Brian ordered! In the end I ordered a 7 element cross yagi for 2m (10dBd) and a 10 element cross yagi for 70cm (11.5dBd) plus a phasing harness for each to allow circular polarisation, fitted to allow right hand circular polarisation.

Well the antennas arrived from Germany 2 working days after ordering and off I went to build them, 2m first then 70cm. As I started on the 2m one it soon became apparent that the holes drilled for the directors were done incorrectly. The boom comes in 2 parts, the front and back (joined at the mounting point in the middle) and even my housemate who came out to help noticed the holed were miss aligned.

2m_Squint_Element

I ended up re-drilling the mounting holes to get it back to being level.  I emailed Wimo on this and with no quarrel they are sending me a new boom section over to replace this one. Wimo are known for their quality so I’ve no idea what happened here – but their customer service is spot on!

Due to the 6m UKAC on Tuesday and the Arran planning meeting on Wednesday I only got round to mounting the antennas last night. They are not very high, about 4 feet up, and they sit in part of the old pond next to the shack well below the bushes, shack, SCAM antennas etc, this is them pointing about 330 degrees.

Sat_Antennas (Large)

Anyway even mounted where they are I can hear the PI7CIS beacon @284Km in Holland, but very weak, if you look at the photo you can see a fence about 1m higher than the antennas which is the direction to PI7CIS! Thankfully there was a VO-52 pass not more than 5 minutes after I got everything connected up and our new Arran DX’pedition member Pete 2E0SQL was about and ready to be active on the pass. So I fired up the HRD satellite tracking software to steer the antennas and low and behold the beacon appeared at 2 degrees elevation! At 5~10 degrees I tuned my IC-910 to where Pete was on the transponder and he was S7! With no trouble at all we worked and he was first in the log on this new setup…

The elements are mounted to the boom direct (and electrically) with a single 50mm M3 cross head screw and nylon insert nut. Fine for permanent installs but fiddly and such like for going /P, i.e. Arran. So this week I got off eBay I got some 50mm M3 hex head screws and M3 wing nuts which will allow disassembly and transport much easier, something we again struggled with with the old HyGain antennas.

,

Satellite Rotator Fixed

March 20th, 2011 | Posted by Gavin, M1BXF in General - (0 Comments)

It’s hard to think that after the issues with the satellite rotator system last year (http://dx.camb-hams.com/2010/05/07/gs3pyep-increase-satellite-operations/) I’ve only just got round to firing up the rotator system to investigate the issue and fix it!

Gav_Sat

Last year we found that the azimuth was going crazy between about 100 degrees and 170 degrees which would put the LVB tracking interface into a spin!  I recently bought a new, but not an exact replacement, feedback pot which I had planned to swap with the current one.  However after opening and removing the current pot it was found the shaft on it was 6mm and the new one was 6.25mm so it wouldn’t fit into the cog connected to the gears!  So with not many other options I opened the casing of the current pot and noticed it was quite dirty inside.  The pot is a 500ohm wire-wound type so a quick clean and rub down with fine sandpaper brought it all back to being shiny! It was then reassembled and on test it is working a treat!

The 2m and 70cm satellite antennas should arrive from Wimo this week coming so should be able to test everything by next weekend.

Thanks to our supporters!

March 17th, 2011 | Posted by M0VFC in General - (0 Comments)

We’re very pleased to announce the following companies who are very generously supporting this year’s DX’pedition:

  • Icom are lending us one of their brand new IC-9100 "shack in a box" transceivers, covering top band through 23cm, including D-STAR support. This has been eagerly awaited world-wide, and we’re delighted to have the opportunity to be one of the first groups to test this rig on a DX’pedition!
  • Kenwood are lending us a TS-590S, their "K3 killer", an HF rig with outstanding performance. Several of us have been looking very longingly at these whenever we visit the Kenwood stand at rallies, and so getting a chance to put this through its paces in a relatively demanding environment is going to be great.
  • Linear Amp UK have once again agreed to lend us their Discovery 64 high power 6 and 4m linear, which performed so admirably last year – on the occasions we got some sporadic-E at least! Here’s hoping for a little more Es this year, which added to our more southerly location, means we’re looking forward to more VHF contacts from Arran. This year they’re also lending us a Challenger HF linear, which coupled with our own Linear Amp UK Ranger 811 (courtesy G1SAA) and Icom IC-2KL (from M0VFC, assuming he repairs it on time) means we should be a good signal on all the bands!

Thank you, all of you, for help making the trip as successful and enjoyable as possible – both for us on the island, and everyone else back at home who we’re hoping to work :-).

,

Satellite Antennas Ordered

March 16th, 2011 | Posted by Gavin, M1BXF in General - (0 Comments)

After hunting high and low for some satellite antenna designs to make and nothing being found it was decided to go and purchase some.  After again looking high and low for decent satellite antennas at a reasonable cost vs suitability we had to goto foreign shores, in this instance WiMo.

In the end we ordered both 2m and 70cm antennas (2m 2×7-Ele 10dBD, WX 7020 70cm 2×10-Ele 11,5dBD) and phasing harnesses for each.  With postage it was a little over £320.

At the Vernon Dutch rally at the weekend a suitable potentiometer was also purchased for the dirty one currently in the satellite rotator so satellites should be much more successful this year.