Project:Clark Trailer Mast

Amateur Radio Club hacking on the Antenna Mast into the Dark Hours of the Winter Night

The London Hackspace has a 30 meter trailer mast currently living in the yard.

It was donated to us in a bit of a worn down condition after sitting in a field for many years. It was originally used by a utility company and repainted in company colours as each utility company rebranded or was acquired. The intended use of the mast is to use it to improve our radio signal propagation/reception at the Hackspace, provide useful utility during field day activities and festivals like Electromagnetic Field and more. The mast can also house a camera and even be configured for semi-permanent mounting.

During the time since acquisition, we've had various challenges from procuring the right parts to having sunny days to service the equipment, but we are getting there. Recently work was stalled due to a bent segment and replacement screws that turned out to be slightly too long once screwed into the assembly. We're getting back to progress on the mast.

Even though this trailer is maintained by the amateur radio club, once assembled, we can share its use with related LHS groups (e.g. quadcopter obstacle course, brain hacker nodule pole, etc.)

Original pledge for replacement parts: Pledge:Trailer_Mast

Clark 63/100 Mast Documentation File:TrailerMastManual.pdf

Specifications

Trailer/Mast Specifications
Make	Clark Masts
Model	63/100 Trailer Mounted Mast Pictures Here
Age	Manufactured during the 1970s
Extended Height	30m (100')
Antenna Attachment	Standard Socket 24mm diameter (Currently has a pole lodged in it)
Trailer Length	5.9m
Trailer Width	1.9m
Trailer Height (with mast stowed)	1.8m
Trailer Wheel Size	185/80R15 Tyres + innertubes
Maximum Recommended Headload	11.4kgs (Over 20m extension) 27 kgs (Under 20m extension)
Maximum Safe Windspeed	16 km/h (Unguyed) 96 km/h (Guyed with middle and top guys)
Picket Radius	18m
Nett Weight (Mast + Trailer)	1,088 kgs
Time to Extend	10 mins
Time to Retract	6 mins
Engine Specifications
Compressor Make	Clark No. 2 Single Cylinder 3" Bore x 44mm Stroke
Engine Make	2hp Briggs & Stratton 4 Stroke Single Cylinder

https://docs.google.com/drawings/d/1m7stWPsxvypnEcJHj0fhJH8rFikoyqbqeej_nzJeFTo/edit?usp=sharing Link to (rough) schematics of mud guards that need to be remade

Work Required

(This is in some sort of vague order)

• Strip existing paint and rust
• Rustproofing
• Replace all seals and serviceable components
  • - this is where we were having trouble - turns out the screws are a little too long and we need to fix this (either by reorder or by grinding down the screwtips 0.5mm)
  • - £165 + vat + delivery for a complete set of seals, O-rings, and grease. Need to provide measurements to Clark.
• Unbend the bent antenna segment or replace from donor SCAM mast

• Painting with a suitable exterior grade paint
• http://www.hammerite.co.uk/products/direct_to_rust_metal_paint_smooth_finish.jsp - Hackspace blue!
  • The original colour was Caterpillar Yellow BS G88/0668. Might be nice to get it in original condition.

• Welding/fabricating replacement parts where required, i.e. wheelarches, reflector arms

Paint Stripping

There is some Nitromore in the engine compartment and some rubber gloves in Velyks's memberbox. Directions for use:

1. Pour amount into metal bucket
2. Dab on a thick layer over painted surface so it's all covered
3. Leave for 40 mins
4. Use scrapers to scrape paint off
5. Clean brush and bucket when you're done

Try and work from the back towards the front.

ALWAYS WEAR THE SAFETY GLOVES AND CLEAN OFF ANY GUNK YOU GET ON YOUR SKIN. THIS SHIT IS NASTY

Replacement Screws

We might as well replace some of the knackered screws. Especially as we damaged some removing them.

• 3/8" BSF x 5/16" Allen Socket Screw
  • Qty: 85

• 2 BA x 9/16" Ch. Hd. Steel Screw
  • Qty: 86

• 2 BA x 1/2" Csk. Hd. Steel Screw
  • Qty: 60

Future projects

• Replace raising crank with electric motor?
• Electric start compressor engine?
• Replace petrol engine with electric motor?

References / External Links

• Paul Sladen's SCAM mast info website - Note that the SCAM mast is a cousin of our WT8 mast in the Clark 63/100 trailer assembly.
• Clark Masts Historical site
• Clark Masts Official Website - good luck getting a response from them!