Pump Up Mast Control

The Clark SCAM makes an ideal mast which can support a large array of antennas.
SCAM's come in two main sizes...
12m / 40 ft called the SCAM 12 or SCAM 40
and
21m / 70ft called the SCAM 21.

All Scam's are based on the same unique and very high specification design... the tubes on the larger masts simply being longer
than those of the shorter masts !

Clark masts are manufactured on the Isle of Wight....their web site is http://www.clarkmasts.com/..
(they cost several 1000's of Pounds NEW )

SCAM's have been used by the UK Military for many years as as such are designed to be VERY ROBUST Indeed.
They are frequently available on the Government Surplus Market or from Classified ads in the Radio Mags or even eBay.
As guide a fully working SCAM12 / 40 costs around £350.
SCAM's can be used in Mobile or Portable configuration if required... many Radio Contest groups use SCAM Masts mounted
on a towable trailer with a 12v compressor to extend.

This Page is aimed at showing how to construct a simple remote control system which will allow you to extend
and retract your mast from your radio operating position.

The diagram below can be downloaded if you wish to save it to your Hard Drive for later use.
Right Mouse Click and select SAVE PICTURE

Additional Notes:
Since posting this diagram I have had several ideas / improvements passed to me by fellow amateurs.
People following this idea might be interested in the following:

If you have a problem locating Solenoid valves try using Washing machine water control Valves.
They are available quite cheaply from W/M spares companies.. or try your local scrap yard !!
They are MAINS operated.. so use a 12v slave relay to control them... I would not recommend having mains cables
running from the shack to your mast so control them with small 12v relays.
They handle the pressure without a problem and let the required quantity of air through to the mast.. a problem with
some compressor type valves.
One Important point... W/M valves are NOT designed to handle Back pressure.. they cope with forward pressure without a problem but are
usually designed to feed into the detergent tray.. ie into open air !!
SO.. they must be fitted the correct way...
UP valve from compressor to "T" Junction
DOWN Valve from "T" Junction to free air
The mast of course connects from the 3rd port of the "T" Junction as in the above diagram
Thanks to Neil M0LAF for this tip

Sealing the bottom section of your mast
If you decided to use a smaller SCAM than the originally designed 8 sections... to save weight and cost... you can seal the
bottom of the sections you use by purchasing a "Pipe Pressure Test Unit"
They are available from most Plumbing suppliers or Screwfix Direct for less than £5.00 !!
Available in sizes from 3 to 18 inches diameter they are ideal for the job... very simple to fit... and are proving VERY Reliable too.
Thanks for Steve G6HOQ for this tip

A Great resource on the web for SCAM users and those who wish to modify
and use a "Part Scam" can be found
on the web site of Paul Sladen.
Lots of very useful information and links to suppliers.
Click Here