Antenna Mount mod

martini · 02 January 2011, 21:32

Probably outside the realms of what most hobbyists are equipped to do but thought I'd share anyway, might be useful to someone:

Richard Selman's folding A-frame with a welded on vhf mount got me thinking a bit more about the need to sort mine out properly as I've never been to happy with them. I've got the s/s fold down type as in pic 1, the main problem with these is the teeth never allow you to position the aerial anywhere near vertical, in either plane, see pic2. Also in most cases there is never any need to adjust the angle more than one direction so the mount could be made simpler thus neater in appearance.

I could be wrong but I think Richard's mount, which is simple and straightforward to do, doesn't incorporate the cam lever mechanism which allows you to fold the aerial down without the need for tools. This is something I wanted to hang on to but it does complicate things a bit.

So 1st job is strip the mount into it's component parts
Take the part shown in pic3 and cut the lug off as in pic4
Next I cut a piece of 6mm 316 plate 45mm wide and drilled a 38mm dia hole in it (pic5)

martini · 02 January 2011, 21:49

Then I shaped the other end to match the 50mm dia tube on my A-frame ready for welding it to the A-frame (pic6)
Then I dropped the previously modified part with the teeth into the hole in the plate, set so the teeth were past the face of the plate and welded round both sides (pic7 +8)
Clean, polish and reassemble et voila pics 9+10 ready for welding to the A-fram tubing

Obviously it would be much easier to weld the toothed disc straight on to the side of the plate but by drilling the hole and insert the disc into it, you retain use of the shaped back of the disc which cams the lever to tighten the whole thing up.

Another note in case anyone else has a go, make sure you orientate the disc so the teeth allow the aerial to go exactly vertical. Raking back your aerial might look cool but at the cost of performance!

Erin · 02 January 2011, 22:04

Looks very nice. I'm all for simplicity in design and use, and I think you've nailed it there. Good use of the New Year holiday weekend I'd say.

martini · 02 January 2011, 22:13

Well it's the only constructive thing I've done all year

Chris · 02 January 2011, 22:29

Is that a video camera mounted on the aframe? It looks like a pan and tilt mount as well?

martini · 02 January 2011, 23:00

Quote:

Originally Posted by Chris

Is that a video camera mounted on the aframe? It looks like a pan and tilt mount as well?

That would be my FLIR camera, joystick control on the console and viewed on the plotter

Also a bullet cam is mounted to the underside of the a-frame as well, barely visible in the pic though

BogMonster · 03 January 2011, 10:56

Quote:

Originally Posted by martini

That would be my FLIR camera, joystick control on the console and viewed on the plotter

Stealth rib, brilliant!

biffer · 03 January 2011, 12:16

Quote:

Originally Posted by martini

Then I shaped the other end to match the 50mm dia tube on my A-frame ready for welding it to the A-frame (pic6)
Then I dropped the previously modified part with the teeth into the hole in the plate, set so the teeth were past the face of the plate and welded round both sides (pic7 +8)
Clean, polish and reassemble et voila pics 9+10 ready for welding to the A-fram tubing

Obviously it would be much easier to weld the toothed disc straight on to the side of the plate but by drilling the hole and insert the disc into it, you retain use of the shaped back of the disc which cams the lever to tighten the whole thing up.

Another note in case anyone else has a go, make sure you orientate the disc so the teeth allow the aerial to go exactly vertical. Raking back your aerial might look cool but at the cost of performance!

nice

they make an airiel mount that fit's around a tube at c-quip, you would only have to machine the base rad to fit your size tube, the clamp is for 25mm, there is enough meat on the mount to machine and weld to 38mm

martini · 03 January 2011, 13:22

Thanks Biff, I don't think I've come across C-quip before, website looks interesting although their online catalogue is under construction at the mo so can't look at their products.

chewy · 03 January 2011, 18:54

Quote:

Originally Posted by martini

That would be my FLIR camera, joystick control on the console and viewed on the plotter

I do like that.

martini · 03 January 2011, 19:07

Quote:

Originally Posted by chewy

I do like that.

If I lost somebody overboard at night it would pay for itself a thousand times over, the rest of time it's a bit of a gimmick and hardly gets used tbh. If I had 2 displays then I could have my chart screen on one and the flir on the other which would be handy (I don't like split screen views). But I haven't. So I can't.

chewy · 03 January 2011, 19:10

Where did you get the camera from?
I could never understand why the RNLI gives us night vision rather than thermal imaging?

martini · 03 January 2011, 19:18

I bought it s/h from Andre, they're seriously expensive brand new, and nothing like the range that police helo's etc use. I'm suprised the rnli haven't got anything thermal either despite the this, even mine makes night vision look as useful as a pair of x-ray specs from the joke shop

jwalker · 03 January 2011, 19:28

Not pissing on your work Mr Martini but have you used these stainless mounts cos I've got two and can't keep them locked when the going gets bumpy? I have to have a wee loop of shock cord to apply pressure to the lever in the lock direction. My nylon one is fine. No give in the ramp is my conclusion. I'd be interested to know how you get on with yours.

martini · 03 January 2011, 19:49

Quote:

Originally Posted by jwalker

Not pissing on your work Mr Martini but have you used these stainless mounts cos I've got two and can't keep them locked when the going gets bumpy? I have to have a wee loop of shock cord to apply pressure to the lever in the lock direction. My nylon one is fine. No give in the ramp is my conclusion. I'd be interested to know how you get on with yours.

I've had 2 of the same for the last 2 seasons covering 2000nm without a single problem

Can't tell you what make they are as they're unpackaged and no identifying marks but I'm guessing they're different to yours.

jwalker · 03 January 2011, 21:02

Quote:

Originally Posted by martini

I've had 2 of the same for the last 2 seasons covering 2000nm without a single problem

Can't tell you what make they are as they're unpackaged and no identifying marks but I'm guessing they're different to yours.

Ta for that. Mine are unmarked too and look very similar to yours. Ah well.

chewy · 03 January 2011, 21:21

They look like what we have on the Atlantics and we haven't had any trouble.