One for the nerds

[Apache]

I've been fabricating tonight too!

It's (or will be when finished) a high gain log periodic antenna for VHF PMR band (430-460MHz). All that's left is to machine the nylon spacers to go between the booms, machine a nylon mount for a mast, fit a BNC connector and wire.

My calculations tell me I should get 8.6dBi gain from it

I expect Matt F will be the only one who appreciates this - and that's not guaranteed!

[BUSHWHACKER]

It's very nice, but everyone is using dishes these days!

[Apache]

Not for those frequencies

For one thing, it'd be a tad big, and have a bit of a narrow beam width. This should be able to 'see' the whole of Worcester and Birmingham with decent gain.

You were messin weren't you... taking advantage of my nerdiness...

[MattF]

Nice. How are the tines secured? Just tight push fit, tapped and threaded or bolted from the other side? Can't quite tell from the pics.

[Apache]

I was going to tap them from the back but they are a tight interference fit so I haven't bothered.

As they make good electrical contact where they push through, I might put a dab of araldite on the end of them to secure them.

When finished, I'll put it in one of our large chambers and plot the gain and acceptance angle properly.

[gwh200]

Well it looks lovely andy.
and it's not nerdy in any way shape or form
I have no idea ( well a little) what your on about, but doesn't a high log antennae cost a hoooooge amount of money.

[Apache]

They can do Gra.

The ones we use at work for measurement are about 20 element for 200MHz-1GHz (mine's 6 element, its covering a smaller band) and cost upwards of a grand. Only a couple of feet long so material cost is negligible (£10 max). However, it's stuff like the certificate of conformity and the calibration that costs the buyer.

I'm building a discone next (a b@stardisation of a biconical and disk antenna) for very specialised high field generation at work. They're paying for materials / my time in my shed for that one.

[charvell]

That is very impresive, i would have no idea where to start with somthing thing like that, well done mate

[Apache]

Well... some are interested in football, fast cars, women...

I like making antennas.

[TobyJug]

Nice Andy......

what cable are you using? and what rig?

[Paul1566]

If your firing super whizzy radio waves about from the malverns way, can you aim them away from tewkesbury as there's enough wierdo's here as it is.....
And its the mop fair this week so there will be a large gathering of cerebral matter that could effect your tests.....NOT...

[Apache]

Paul - Mop fair? Whats that then?

Toby - Rx only mate (though I intend to at least try it's efficiency in Tx when I calibrate it in work), into either a Bearcat 780XLT, a Realistic Pro 2042, a GRE295 (I think!) or an AOR-1000, via a Scanmaster 20dB pre-amp if the need arises.

You want nerdy? You got it!

[Paul1566]

The mop fair is on 9th and 10th october.
The fair ground folk take over the streets of tewkesbury for one of the biggest street fairs in england.
They fill the carpark by the swimpool and fill the high street and surrounding roads with fair rides......
Its free entry and if i recall right the ride prices go up after 8pm......thieving buggers...
We just go and soak up the atmosphere....

Last year they had the largest mobile ride in europe there it was frigin massive and way high you could see the lights for miles...