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.

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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.

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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.

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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.

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6m Rotator Upgrade

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


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.

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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 :

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

John G4BAO