Saturday 28 June 2014

Repairing my Walkabout mk II

Last weekend in the North of England was graced by glorious sunshine and radio rallies on both Saturday and Sunday - perfect conditions to take drives in the country...

Saturday saw the XYL and I take the short run to Bickershaw, for South Lancs Amateur Radio Club's Summer Rally at the Bickershaw Labour Club.

I didn't find much to enthrall me at the event - but I was tempted by a scanner antenna, which looked as if the telescopic section could be just the thing to repair my Walkabout mk II's top section, recently damaged on Aldeburgh beach...


I paid £3 for the donor part - which seemed fair for the complete antenna, even though it was a bit steep for a cheapskate like me who was intending to take it home and tear it to pieces!

On getting back home and stripping off the heat shrink at the base, I confirmed that the telescopic section was indeed exactly the 48 inch length that I needed to replace the broken section of the Walkabout - seen here below the donor scanner antenna...


I removed the loading coil and BNC from the donor and decided I would try to recover the brass base from the broken Walkabout part to save the female 3/8 inch 24 TPI thread...


Unfortunately, in unscrewing the antenna from this base component, the threaded stud from the antenna sheared off and could not be removed - so I drilled it out and tapped the over-sized hole 2BA.

I then made a brass coupling piece with a 2BA male thread at one end and an M2.5 female thread at the other to accept the new telescopic whip from the donor...


A final covering with heat shrink and the new antenna top section is complete - differing only from the original by being slightly less stealthy (in its bright chrome finish) and a little longer when fully extended (which won't hurt tuning at all)...


Not a bad result for £3 - for anybody else wishing to follow in these footsteps, I note that 48 inch telescopic antennas can be had on eBay from Far East sellers for around £3, including shipping.

I haven't had any QSOs on my new antenna - but I have confirmed it tunes up on 40m and the FT817 gives exactly the same indicated SWR and Power Output as before - result!

Sunday offered the LAMFEST Rally at the Elsecar Heritage Centre, so a blast over the backbone to Yorkshire was indicated.

Now this is what I call a Rally location - combining Radio and Railways AND some entertainment for the XYL (gift shops, antiques, vintage clothing shops, cafes etc) all on one site.

We were met by views of a little ex-Coal Board 0-6-0 Saddle Tank plying her trade in front of the car park as soon as we arrived...


I got myself a Sealed Lead Acid brick to enjoy longer visits to future beaches with the repaired antenna. There was even a COMPLETE Walkabout mk II on offer for £25 - a good deal for somebody!

A great weekend.

 ...-.- de m0xpd

Thursday 19 June 2014

Walkabout on the beach

I was fortunate to spend last week on the beach at Aldeburgh, Suffolk. I took my FT817 and Walkabout II Antenna, hoping to work some /p.

Well - I have to report a pretty poor show - I logged only one contact (with Richard, g0iln, in Bexhill, who also was running an FT817, but into a "real" antenna). I was only trying to work G stations - mainly FISTS calls. Perhaps I would have done better to turn my attention to the continent, where I've had better luck with the same portable equipment before.

Nil desperandum  -  band conditions were the least of my problems...

Packing away one day I accidentally bent the telescopic section of the antenna, which promptly snapped...


I thought that would put an end to the week's activities on 40m (the Walkabout II needs the full length of the telescopic section to tune up on 40 metres) but the good folks at MCT Electrical on the High Street kitted me up with an off-cut of garden wire which I could stuff inside the broken antenna and I was back on air.


All their kind efforts were in vain for, try as I might, I could not raise a further contact. I reverted to a different interpretation of "Walkabout", which turned out to be infinitely more fruitful...

Aldeburgh's beach is graced by two conspicuous "Lookout" buildings, once operated by two rival companies (known, as I discovered in the interesting little museum in the Moot Hall, as the "Up-Towners" and the "Down-Towners").

The Southern Lookout is now owned by Caroline Wiseman...


This ecclesiform curio, with its west tower and its east opening to the dawn, lives up to its billing of a "tiny temple of inspiration for artists, poets, writers, performers and thinkers".

It drew me in when I wandered by, because it was playing host last week to a collaboration entitled "The Awe of the Other"...



The collaboration was between Pauline and Matthew Bickerton and Thomas Garnon. Most of their work soars high above the scope of this mundane blog. But Matthew's practice embraces some technologies of real interest and significance to us...

The "Otherness" implied in the "Awe of the Other" title refers (in part) to impromptu conversations between members of the public who choose to sit on two larger-than-life chairs placed some 100 metres apart on the beach, facing the horizon (seen in the images above). Snippets of these conversations have been recorded and assembled into a work which was exhibited on Saturday, 14th June, in the Lookout. Part of this "performance" was delivered through a modified radio.

Matthew took an old domestic radio and fitted a custom media player, which he built around an Arduino-compatible system. The host radio and the new internal media player is seen here...


The tuning mechanism (which originally drove a ganged variable capacitor) has been retained but modified to drive a potentiometer and so generate a voltage, which is sampled to allow the user to select 1-of-n saved sound files (rather than to tune the radio to a station). 

Matthew's custom media player is seen in close-up here...


It uses a Teensy 3.1 (which itself has a ARM processor - similar to that on the Arduino DUE), sitting atop a Teensy Sound Card (which hosts a MicroSD Card for Mass Storage - just visible in the photo) and a digital power amplifier, seen on the blue evaluation board to the left of the photo.

It turns out that Matthew is no stranger to bringing bespoke technology and art together in exciting new ways, as is exemplified in the Guerilla Dance Project.

 Great to see people making beaches MORE beautiful for a change!

 ...-.- de m0xpd