The Problem

I wanted to start participating in VHF contests. Aside from a radio, a hilltop location and help from my friend M0AKT, I had nothing. After an initial start with a 4 element 6 Meter beam, a Clansman 5.4m 6 section fiberglass mast and manual rotation system, we concluded we needed more height, a bigger antenna and a rotator.

The Options

I then started researching the mast options:

• Pump up Masts: Several 9m and 10m Clark masts were available on eBay but I had two concerns. Firstly, some sellers suggested losing pressure was a ‘feature’ whereas others said they shouldn’t, leaving me confused about was and wasn’t correct. Furthermore some sellers didn’t even know whether theirs did or didn't! Secondly, some specific models for sale were bespoke variants and I was concerned about getting spare parts. The possibility of losing pressure and challenges with spare parts? This sounded like hassle.
• Trailer Masts: The main issue here was cost, though storage and transport were also a concern. Again, there was several available on eBay of varying condition. With the need to store it somewhere (they’re not small) and the not insignificant issue of not having a vehicle with a towbar, I ruled this out too.

The SpiderMast

I then came across the SpiderMast, manufactured by SpiderBeam in Germany. The SpiderMast is made up of lightweight telescopic aluminium sections, each secured by a clamp and allen screws. They offer a range of masts from 10m to 18m with Heavy Duty (HD) versions available for permanent installations.

Having considered the practicalities and costs of all the different heights available I settled on the 12.5m (41ft) version. I was concerned that the 14.5m and larger versions would be impractical to raise with just two of us and ultimately my decision was made when I established the total length of the guys was just short of 100m, meaning only one reel was needed (more on this below)

The SpiderMast Options

SpiderBeam also offers a range of cool add ons:

• A Tripod: At just over 70% of the cost of the mast itself I wasn’t convinced this was value for money – I was wrong. It takes seconds to setup the tripod and then the mast is upright and ready to attach the aerial. Furthermore it is surprisingly good at holding the mast steady even at height before the guys take over
• Rotator Adapter: This neat add on means the rotator can be attached at the bottom of the mast. I really liked the idea of this as opposed to hoisting both the antenna and rotator up 41ft in the air. The smallest of the Yaesu rotator range, the G450C, is sufficient for the job
• Guy Plates: Two options are available allowing for 3 guy and 4 guy systems. Here, the plates come with a bush (a short aluminium section) on which the guy plates sit to allow the mast to be turned inside the guy plates

The Mastrant Guying System

So, I now have a mast, tripod, guy plates and rotator. Next, some suitable guy ropes.

I then discovered Mastrant, who offer a full range of guy ropes and all associated couplers and terminations. They also have an excellent website that provides really clear advice and sizing information for a range of mast and antenna types.

Two synthetic guy options were available – Mastrant-M and Mastrant-P – with Mastrant-M being the better of the two with less stretch and more strength (and a price tag to match) Reading the sizing guide it gave a range of M4 to M6 so I decided on the Mastrant M5, sized for a mast heights up to 20m and a 5 element beam for 20m. The M4 would almost certainly have been sufficient but I was intentionally cautious. The terminations were also specified in the Mastrant guide, something I copied literally.

Guy Lengths

DJ0IP has really helpfully calculated the required guy lengths for the range of SpiderMast heights. For the 12.5m with a 3 guy system it states 88m is needed plus a further 12m (2m per guy), equating to exactly 100m. Perfect!

As I mentioned above, this was a factor in the decision. The Mastrant-M is expensive and in comparison the 14.5m SpiderMast would have needed 167m of guy rope.

Base Plate and Ground Stakes

These I had made. For the base I’ve a thick, square, very heavy steel plate that the rotator screws onto. I originally thought this was overkill, however, the weight at the bottom helps enormously when extending the mast to prevent the rotator and bottom sections lifting as you push up the rest of the sections. For the stakes these are made of angle iron welded together with holes for the guys, an impact pin for the mallet and a ring for extracting them from the ground

In Action

So far the setup has had one outing for a 4m contest in Feb 18 – it all worked a dream! A couple of things I am going to do next time around:

• Bring some decent gloves. Particularly when extending the final sections there is a lot of weight to lift. A good grip and more importantly to protect your fingers if the mast was to slip, decent gloves are a must
• The SpiderMast uses an allen key to secure the sections when extended. Needing both hands to extend the mast, hold it place and then pick up the allen key to secure the sections is a challenge – I kept dropping it. SpiderBeam offer replacement screws with plastic knobs that can be tightened by hand. I am going to buy these.

Conclusion

Overall I am really pleased with the setup and feel I made the right decision. The whole setup can fit into the back of a car, it is lightweight and therefore very portable. Infact I’ve also used it many times at home – it takes minutes to setup and with the tripod is sturdy to at least half height without the guys.

Links

Link - The SpiderBeam Website
Link - Guy measurements courtesy of DJ0IP
Link - The Mastrant Website
Link - The Mastrant Guy Sizing Guide

Parts

International delivery was available from both SpiderBeam and Mastrant though i bought all the parts from Nevada. The parts list is:

• 1 x Spiderbeam Spidermast 12.5m
• 1 x Spiderbeam Spider Tripod (XL)
• 1 x Spiderbeam GP10/12 Guy Plate sets (3 Guy Version)
• 1 x Spiderbeam RA 8050
• 1 x Mastrant M5-MM05100
• 6 x Mas ATH05mm Cable End Thimble
• 6 x MasADC05mm Duplex Rope Clip
• 6 x Mastrant CL-271