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VHF and Up Stations

April 29th, 2014 | Posted by Gavin, M1BXF in General - (0 Comments)

This year we have again put all the VHF and up stations together in Flossie, These are;

  • 6m = JT6m, ISCAT-B & SSB
  • 4m = FSK & SSB
  • 2m = MS and JT65 (EME)
  • 23cm = JT65 (EME)

Flossie_VHF

This makes sense as we find the same stations usually want to work us back to back on all the different bands and with 2 operators we can run 2 bands each (6m + 4m) & (2m + 23cm).

Find us ON4KST chat.

4m Update

April 29th, 2014 | Posted by Gavin, M1BXF in General - (0 Comments)

So 4m has not had the best start.  We are experiencing higher than usual inter-station breakthrough from HF into the 4m RX, here is an example of it at its worst;

4m_QRM_270414

This is a combination of about 3 HF stations, and as you can well see it’s impossible to work anything on 4m through this QRM.

Lots of investigations ensued and found that even at low power levels, 100w, and with all stations using band-pass filters, the interference was still apparent and we had no way to cure it, the only conclusion is we have something nearby which is causing a “rusty bolt effect”, there is little chance of curing it.

The site we are operating from is an old Decca transmitter site used for navigation and we believe there is a network of ground radials underfoot and the building has an integrated faraday screen, and probably many other pieces of metalwork we have yet to see.

The good news is we have found a combination of bands which work now well with 4m and 4m operation is yielding QSOs again, so if you see us on the band, or on ON4KST chat, then give us a call.

One issue though, and it’s a biggie, is during the investigation phase, alignment of a backup transverter was in progress when it went into TX oscillation which resulted in too much RF power being delivered into the MRF-151G final PA which in turn destroyed the device.  The workaround has been to use the Yaesu Quadra on 4m as the final PA driven from the G4DDK 7w RA07H0608M pre-drive PA, this setup can achive 80w out the Quadra on 4m, this isn’t so bad as it’s only 3dB down on the MRF-151G output.  It does mean however 6m must run barefoot (80w) from the K3 when 4m is using the Quadra but can be set back to 400w when 4m is not in use.

This morning a group of thirteen operators will be heading off to the Isle of Lewis via Fort William during our travels you will be able to track us on APRS but also we’ll be operating HF mobile while on route (Recommend watching the DX Cluster and Twitter).


http://aprs.fi/#!mt=roadmap&z=11&call=a%2FM0VFC-9%2Ca%2FM0BLF-9%2Ca%2FG1SAA-9%2Ca%2FG0DDX-9

We should arrive on the Island on Saturday the 26th and be on air soon after, we will be covering the HF bands with five simultaneous stations, while the 6m & 4m stations will have a great take-off towards the UK and Europe from the island’s northern tip in IO68 square. All stations will be able to run at the full UK power limit.

EME operations will use 150W to 55 elements on 23cm and 400W to 17 elements on 2m. Primarily on JT65 but also available for CW skeds – if your station is big enough.

Satellite operations on 2m & 70cm will use X-Quad antennas and a fully automatic Az/El tracking system.

Contest operations will take place in the RSGB 70MHz UKAC on 29 April.

A number of the group hope to make an extra trip to operate as GS6PYE/P from the Shiant Isles (EU-112). They are aiming for afternoon/early evening operations on 28 April, but may switch to 30 April if the weather is bad.

We will be doing our best to share as much information as possible about the operation on the blog, but also Twitter (#Lewis2014), Facebook and Youtube.

This year we have an updated 4m transverter based on Sam G4DDK’s Nacton transverter. 

2014-04-12 10.13.44 

The transverter can receive signals from the generator down to, and beyond, –140dBm and can output 300w meaning running data modes at 50% duty cycle at 150w is easily possible.

A full write-up of the transverter, and it’s history, is available on Gavin M1BXF’s  webpage.

We are rapidly approaching leaving for the Isle of Lewis and my inbox has regularly been getting requests for satellite QSO skeds especially with stations in North America – I’ve just run the predictions for the week we’re on the island in SatPC32 which has generated a nice list of possible passes which can be found at https://docs.google.com/file/d/0B_1dHk8Yo754eHlkTlhBQmRsam8/edit

I’d recommend if you’d like to try a sked that you try request  satellite passes from Sunday the 27th onwards, clearly its dependant on someone being available but we’ll do our best to make sure someone’s available.

You can request satellite skeds by either emailing us at skeds-2014@camb-hams.com or sending @2e0sql a tweet. We will do our best to tweet which passes we will be on.

Mast Bearing for 6m

April 21st, 2014 | Posted by Gavin, M1BXF in General - (0 Comments)

Tis year the 6m beam will be mounted on the Camb-Hams /P trailer mast at 13m AGL.  The mast itself is 10m and it is at this point we mount the Ham IV rotator and above the rotator will be a 4m pole which we normally put both the 6m and 4m beams on.  This year we are putting 4m beam onto Flossie’s 20m mast and will mount the 6m beam near the top of the trailer mast pole at about 13m and above it a Solarcom imax-2000 vertical for 10m.

This leaves lots of potential movement above the rotator on a windy day so we have decided to support it using a slip-ring.

2014-04-17 23.40.53

We are using a Yaesu GS-065 which comes with handy guy rope mounts and to connect to them 4 runs of 8mm nylon rope terminated with thimbles and D shackles which will make assembly much easier.

2014-04-21 22.19.40

This preparatory work I can not stress enough.  The few hours effort back home means we know the guy connections will be good whoever connects them to the guy points, no worries about bad knots, and the time to assemble and pack away is much reduced, which if the weather is poor at setup or teardown you’ll be very much appreciative of the effort you put in before setting off.

As there are 2 guy points on the 6m mast, the lower one is at the rotator 10m up and the second will be at the guy slip ring 3.5m above that.  As such we have 2 different lengths of guy rope, the tops ones are 23m and are marked with “TOP”, the bottom ones are 20m.

Originally John G4BAO made this up a guys slip ring before I opened my new GS-065 box to find Yaesu supplies the rope attachments.

2014-04-21 22.17.36

My only concern with Johns design is the stress on the right angles, this thickness of extruded aluminium should be OK, however the supplied Yaesu parts seem better and less likely to fail, this is just me being over cautious.

GM3SEK HF Chokes

April 21st, 2014 | Posted by Gavin, M1BXF in General - (6 Comments)

We find that vertical antennas work for us on most bands.  We also use vertical Dipoles for HF bands above 20m, there are a few reasons why verticals should be considered for a DX’Pedition;

  • Low weight to transport
  • Small size requirements to transport
  • Quick and easy to setup
  • Easy to tune and change as required
  • Minimal guying needed (3 only)

The only draw back is RF can flow back down the outer of the coax radiating in places it shouldn’t.  This is acceptable (but not ideal) in a single station environment but can be a contributing factor to breakthrough issues in a multi station operation like we normally run, this year upto 5 HF and 4 VHF stations running at one time.

The way to solve this is to add a choke to the coax.  Some people just make 6 turns of coax at about 5 inch diameter but this is not always sufficient.  Ian GM3SEK has written lots on the subject of chokes and  this year we have made some to help improve our station.

2014-04-19 16.01.062014-04-19 16.02.30

2014-04-19 16.01.472014-04-19 16.01.32

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6m Rotator Upgrade

April 21st, 2014 | Posted by Gavin, M1BXF in General - (0 Comments)

Ham-IV_Original

One thing which was noticed in the Mull2013 DX’Pedition was how annoying a south stop rotator was on 6m. Moving between SP and CT was via north and *very* slow.

We use Gavin M1BXF HAM IV rotator and this year he’s done some updates to it.

2014-03-25 00.53.25

1296MHz EME tests

April 14th, 2014 | Posted by G4BAO in General - (0 Comments)

Thanks to everyone who worked me (or tried to) last night on our 55el Yagi +150Watt system that I’m taking to the Isle of Lewis IO68 a week on Friday. The exercise was very worthwhile, as I shook out a number of bugs in the system, which was my first use of my TS2000X direct on 1296.

First of all the TS2K was 890Hz off frequency, so this morning I’ve reset the TCXO against a Rubidium locked sig gen and I should now stay within 100Hz or so.

Secondly the “dreaded TS2KX fan drift” was very obvious last night, so I’ve done the K0BT mods to run the fan slowly on receive, and that seems to have done the trick.  http://www.mods.dk   Nice one Bob for that simple mod!

The two “big guns” I worked, HB9Q and UA3PTW were “CW copy” level. The other station I worked,  I1NDP would probably also have been workable on CW with some effort. If you have that size of station, I’ll be happy to try a CW sked from IO68.

See the Sked request page for details :
http://dx.camb-hams.com/dx-peditions/gs3pyep-sked-request/

After about 21:45, the moon was behind some trees so that would probably explain my failure to hear people after that time. The Isle of Lewis is far enough North not to have many trees, so that will not be an issue from GS3PYE/P.

Remember we are also taking 144 JT EME 400Watts to a 17 element and will be QRV on 70 and 50MHz MS as well as all the HF bands

73
John G4BAO
dx.camb-hams.com

23cm-eme

This year we have decided to improve upon our satellite operations from the Isle of Lewis, the original plan was to use a simple setup of a Yaesu FT-817 and a Arrow satellite yagi – although this setup works amazingly well as we proved last year on the Isle of Mull it does have the downside of making you stand outside in all weathers, and this year we are further north!

photo of the Wimo X-Quads setup for testing in G1SAAs garden.

Wimo X-Quads setup for testing in G1SAAs garden

So this year we plan to trial Bob G1SAA’s satellite equipment from the island, the new station comprises Wimo X-Quads for 2m and 70cms with SSB electronic Preamps (SP-2000/SP-7000) and a Yaesu G-5400B Az/EL rotator supported on a speaker stand.

Inside the shack we’ll be using a Foxdelta ST-2 tracker (LVB Clone) connected to the rotator & ICOM IC-910 transceiver, this will all be controlled using a laptop running SatPC32.

We’ve had a number of people asking what satellites we will be using, these will be the ones we target;

Satellite Uplink (MHz) Downlink (MHz) Mode(s ) Website
AO-7 (Mode B) 432.125 – 432.175 145.975 – 145.925 SSB / CW http://goo.gl/s2p4za
VO-52 435.225 – 435.275 145.925 – 145.875 SSB / CW http://goo.gl/wk7R1v
FO-29 145.900 – 146.000 435.900 – 435.800 SSB / CW http://goo.gl/IjuHUq
SO-50 145.850 436.800 FM http://goo.gl/ibjXyx
AO-73 435.150 – 435.130 145.970 – 145.950 SSB / CW http://goo.gl/wqq7Rt

All bar one of these are SSB/CW transponder satellites, see the AMSAT guide on linear transponder operating if you are unfamiliar with it, although our main focus will be SSB QSOs we can probably do CW as well however we’d recommend that you send in a sked, or ask on hf, so that we can make sure a suitable operator is available.

Of course if any other satellites with transponders become available we’ll of course endeavour to use those as well. And I’m sure you’ll still hear us using our Yaesu FT-817s and a Arrow satellite yagis if the weather is nice.