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SCAM mast control (was 'Test')

Phil Guttridge G3TCU
 

Hi Neil,

I have a SCAM 12 mounted through the roof of my 4WD Transit van and I
stand on the roof to lock each section as it goes up, so I use a UHF
remote fob e.g. like eBay item # 192729265039 and a solenoid valve after
the compressor (which is inside the van). I use one UHF channel for up
and the other for down (which operates a vent valve). It sounds like
this might be a good plan even if you are on terra firma when pumping up
a SCAM mast!

BTW I use the other two UHF channels to operate a linear actuator that
engages or disengages a G-1000DXC rotator which is belt coupled to the
base of the mast, so I can 'unlock' the rotator when I'm on the roof and
swing the antenna to a chosen starting direction.

73, Phil G3TCU

On 30/11/2019 16:01, Neil Smith G4DBN via Groups.Io wrote:

Hibernation here Ralph, although I did pump the dish up to full height
and could hear a sniff on KBQ on 3cm, plus lots or nice fat aircraft
scatter.  Then the dratted thing froze wolid, so I had a lot of fun
with gallons of hot water and a pump-action pistol trying to unfreeze
it in the pitch dark at 1.30am.

I've got the heater on in the machine shop and I'm making a batch of
Rexolite lenses for QO100 antennas and three 3.4GHz feedhorns and a
pile of stuff for 122GHz, oh and a 24GHz milled waveguide preamp
enclosure and three 24GHz milled copper PA enclosures and some DF9IC
spreaders and several W6PQL spreaders and some heatsinks for 70MHz PAs
and about a dozen other projects, include two 500W 23cm PA enclosures
to complete. Keeping busy, but I've dome something hideous to my left
shoulder so I can't lift anything, which means zero chance of getting
the SCAM which supports the 70/23/13cm stuff back up to vertical until
a squad arrives to assist.

All of which means I haven't been able to ask any daft questions on here.

I could ask "What is is like when you are pumping up a SCAM12 and you
realise too late that the heavy power feed cable is caught round your
leg and you can't reach the air tap fast enough to stop it and your
leg is so far off the ground that you are doing the splits and there
is nobody at home or within yelling distance?"

However, I now know EXACTLY what it is like.  I had visions of being
found the next morning, hanging upside down by one leg.

Now luckily, I am possessed of an immensely large amount of
gravitational attraction to terra firma.  Swiftly and with amazing
dexterity, I wrapped the other feeders round my good arm and pulled
like hell.  That just balanced the 22psi air pressure from the
compressor regulator. I managed to pull the thing down about 3ft, but
the additional area of the next piston was too strong.  No hope of
reaching the tap, even with my bad arm, but I gained a tiny bit of
slack and I managed to shake my airborne leg enough so the lasso
loosened a bit.  After a good five minutes of vigorous wriggling and
calisthenics, involving the cable snagging on my boot and a lot of
expletives, it let go.

Now I just had the issue of the feeders around my arm with a pull of
at least half my weight.  If I let go, the pressure would launch the
dish and top sections into space for sure.  I could reach the tap, but
needed two hands to disconnect the air line. I decided to wrap the
feeders round my leg again, but in a spiral, and trod on the feeders
with my other foot.  That let me unwind my now numb, cold and white
arm.  Once the blood returned to the poor mistreated limb, I released
the feeders gradually and the dish went up nice and gently to full height.

That four-strand sinnet plait cable grip I made from Kevlar braided
rope is REALLY strong.

Neil G4DBN (with some hard-to-explain-to-wife rope burns and bruises)

On 30/11/2019 15:12, Ralph via Groups.Io wrote:

Excuse the bandwidth, but nothing received for two days approximately

From the group.

I was wondering if everyone has hibernated or there is a problem

With the email server.

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Neil Smith G4DBN
 

I have now rigged an emergency valve with a lanyard so I can release the pressure through a small orifice if I pull the pin. The power lead is about 3m too short, so it is separate from the feeder and control cables.  The air comes from my machine shop compressor. I just need to sort it all out and fix a three-way tap plus the emerghency release lanyard pin, but getting on the air is FAR more important than safety of life and limb in my (admittedly skewed) priority list!

I do rather like the idea of full remote operation though.  My microwave SCAM stays up for 3 days or so before it loses pressure, so I don't need to lock the sections.  The UHF one lasts 18 hours before it starts to drop a bit. Fitting an outside webcam and remote valves would be very nice. I often get a pint of icy water down my neck when a section reaches its full extent as I'm leaning down to turn the air off.

Base rotation is on the list of jobs, I use that on the VHF masts and it is hugely better than a Yaesu or anything, with better than 0.05 degree resolution and slew rates up to 12 seconds for 360 degrees. I use a wheelchair geared motor and belt drive.  The SCAMs should spin nicely with a similar setup.

Neil G4DBN

On 30/11/2019 18:10, Phil Guttridge G3TCU wrote:
Hi Neil,

I have a SCAM 12 mounted through the roof of my 4WD Transit van and I
stand on the roof to lock each section as it goes up, so I use a UHF
remote fob e.g. like eBay item # 192729265039 and a solenoid valve after
the compressor (which is inside the van). I use one UHF channel for up
and the other for down (which operates a vent valve). It sounds like
this might be a good plan even if you are on terra firma when pumping up
a SCAM mast!

BTW I use the other two UHF channels to operate a linear actuator that
engages or disengages a G-1000DXC rotator which is belt coupled to the
base of the mast, so I can 'unlock' the rotator when I'm on the roof and
swing the antenna to a chosen starting direction.