Sunday, 14 April 2013

Scam 12 Develops Air Leak

Scam 12 Maintenance and Repairs

Available on the market and used by a lot of amateurs is the scam 12 telescopic mast made by Clark. Created in the  mid 1960's to provide
 the military with a versatile field and vehicle mounted mast for vhf/uhf antennas then in use.
I purchased mine in June 2011 and installed it not long after with my G-600RC rotator and my Cushcraft MA5B
 mini beam mounted on the top. It worked great every time I came to use it with no hassle. After a break of a year
 from radio I came to use my equipment again pumping the scam 12 up. The top section I had left fully extended on
 my break thinking nothing of it. When using the mast I noticed the top section the 2 1/2" tube (item 3 in the
 diagram below) would not come down it was stuck up even when all the air released and collar slackened off to let
 the tube down. When pumping I could hear air escaping from the top tube and the mast would not pump up. After
 taking the mast to pieces here is what I found. The top Piston (Item 6 on the diagram below) had an issue with the
 screws corroding causing them to break inside the piston (item 50 in the diagram below) which then made the
piston insecure causing an air leak when trying to pump the mast up. Also upon inspection the inner tubes had
 gathered a residue of dirt and grit which eventually would have worn the tubes, seals and O' rings (Items 42 & 46
 on the diagram below) A lot of wear was present on the top 3 pistons (3 1/2", 3", 2 1/2") so they was to be replaced along with the seals. You can read the full write up by clicking here


Monday, 1 April 2013

A rest from amateur radio I'm back surfing the HF bands

After about a year off amateur radio my enthusiasm has regained itself and I'm back surfing the HF bands. Thanks to Daz M0TPS letting me know what I'm missing. After been put off and not been able to use my radio equipment due to interference on the HF spectrum and ofcom not being able to find it telling me to buy a noise filter I recently purchased the MFJ1026 noise canceling signal enhancer. To my surprise working radio without having to put up with interference was a great pleasure it was like someone had turned my radio on again. Fantastic I can have a shout and ball on HF again from home rather than from the car. So bank holiday weekend saw the wpx contest take place. "Great" a chance to try out my station in over a year. Out I go into the garden to pump my scam 12 mast up to find it frozen and full of water. My first task was to release the valve and let all the water out. Then boil the kettle and pour over it to warm it up ready for the great launch. So after around an hour or so maintaining the mast up she went to 35ft after been on the ground at 10ft since June 2012. Kettle on and upto the shack with a coffee to start the pc's up and the radio's and I bet they got the shock of there lives. Anyway working a host of stations including: Uruguay, Puerto Rico, Venezuela, Argentina, Bahamas, Bonaire Island, Virgin Island, Trinidad and Tabago Island, Cayman Islands,  Mexico, Ecuador, Cuba, Tunisia, Chile, Colombia, Aruba, Kyrgyzstan, Senegal, Cape Verde and Brazil with a few others thrown in for good measure. All in all glad to see my station still working well and now looking forward to a spot of summer dx.