Home brew

Post by **robbage** » Thu Jul 10, 2008 11:08 am

Anybody making their own gear, antennae in particular?

WPXZBP · Post by **WPXZBP** » Thu Jul 10, 2008 2:28 pm

After I come back from Perth I will hopefully have some coaxial cable. I will then be making a delta loop for 40m and one for 20m. We'll see about the rest.

Post by **robbage** » Thu Jul 10, 2008 7:02 pm

The fest might be fruitful for coax. I was going to sell the RG213 I have, but I might just can that idea.
I built a 2m Â¼ wave gp this week and was hoping to put up a small mast + that today, but mother nature and bad planning stuffed that idea. Need a hole in a tile, I think.
Looking at J-pole and Sperrtof eventually. Or maybe 5/8. I'd really like dual 2m/70cm since I spent the money on the transceiver. I'm stuck with a vertical dipole hanging from the curtain rail ATM.
Fortunately I'm not dealing with 20 or 40m just yet. The curtain rail isn't long enough

WPXZBP · Post by **WPXZBP** » Thu Jul 10, 2008 7:43 pm

robbage wrote:The fest might be fruitful for coax.

Problem is I need the co-ax NOW.

robbage wrote:Need a hole in a tile, I think.

Nah, get yourself a satellite dish mount. Hills make them I think. Mount the antenna to where the dish hangs on.

robbage wrote: The curtain rail isn't long enough

Post by **robbage** » Thu Jul 10, 2008 10:42 pm

WPXZBP wrote:
robbage wrote:Need a hole in a tile, I think.
Nah, get yourself a satellite dish mount. Hills make them I think. Mount the antenna to where the dish hangs on.

I'm not familiar with them. How do they fix to the roof and will they support a 2 or 3 metre mast with an antenna? The weight won't be much but the lateral stress from wind could be a factor if it's anchored to tiles.

Post by **jasonjag** » Thu Jul 10, 2008 11:11 pm

[quote="robbage"][quote="WPXZBP"][quote="robbage"]Need a hole in a tile, I think.[/quote]
Nah, get yourself a satellite dish mount. Hills make them I think. Mount the antenna to where the dish hangs on.[/quote]

I'm not familiar with them. How do they fix to the roof and will they support a 2 or 3 metre mast with an antenna? The weight won't be much but the lateral stress from wind could be a factor if it's anchored to tiles.[/quote]

I Installed my SCABase antenea today, using power saw, cut a piece of tile away, bolted a 5cm x 10 cm x 100 cm box pipe to roof rafters, sealed the tile with cartridge gutter silicone, then added another piece of box tube over that and welded the 25 ft mast to that, welded a chain link at 20 ft and used 3 plastic coated steel stay cables to eyebolts, drilled hole through tile and rafter and siliconed the hole area for the eye bolts. welded flat plate with positioned holes at top and used U bolts, slid PVC tube over U bolt to clamp Antenea to plate. have fantastic reception. jj

WPXZBP · Post by **WPXZBP** » Thu Jul 10, 2008 11:14 pm

The one I was given simply is screwed to the beams that hold up your roof tiles. It consists of the main section incorporating the dish mounting, a securing section which is held in place by the screws and a horizontal piece of square tube. A second piece slides into the square tube. This consists of another, narrower, square tube onto which a piece of flat plate is welded. This plate is what is secured onto a second roof beam. The two pieces of tube are screwed together for added strength.

This picture shows what I mean.

I'm not sure how good they are but my Diamond X-200 is still up there.

Post by **robbage** » Fri Jul 11, 2008 8:24 am

Thanks guys. The picture helps. I don't have a power saw, but I do have an angle grinder and a pile of left-over tiles

Found some interesting ideas for building a VSWR meter as well.

Blinky · Post by **Blinky** » Fri Jul 11, 2008 4:37 pm

robbage wrote:
I'm not familiar with them. How do they fix to the roof and will they support a 2 or 3 metre mast with an antenna? The weight won't be much but the lateral stress from wind could be a factor if it's anchored to tiles.

"should" be ok. There would be a fair amount of wind resistance from a satellite dish.

If it handles that in the wind, a smallish mast and antenna "should" be able to stand it.

"should" = famous last words

Phil...

Post by **robbage** » Fri Jul 11, 2008 8:57 pm

After looking at the mast and antenna again, I'd say more like 4-5 metres. Doesn't matter; all sorted. My wife will kill me if she sees what I did. Non-acidic RTV is your friend.

Any tips on short mobile antennae for 2m? Â¼ wave hits carport, no decent GP lower down... leased work ute so need to avoid hood & bumper. Can I top load the one I'm using a little and shorten it?

Post by **Toottoot** » Fri Jul 11, 2008 9:49 pm

Never anchor to the tiles - make sure it is to a beam (thick bits of wood holding the thin bits of wood) and not a batten (thin little bits of wood).

You can get those weatherproof seals, sort of like a telescopic rubber mat, to go around whatever comes through the roof.

Post by **robbage** » Fri Jul 11, 2008 11:16 pm

Yup. 40mm al tubing fixed to beam with 8mm ss bolts. Good enough for vhf/uhf verticals.

Post by **VK6ZMS** » Sat Jul 12, 2008 8:55 am

robbage wrote: Any tips on short mobile antennae for 2m? Â¼ wave hits carport, no decent GP lower down... leased work ute so need to avoid hood & bumper. Can I top load the one I'm using a little and shorten it?

Try one of these mounts on the hood, they don't mark the paint.
Mine preforms well on the boot.

http://tinyurl.com/6d6l4w

Andrews sell several different length Super Gainer 2/70cm mobile antennas.

http://www.andrewscom.com.au/site-section-08.htm

btw
I did earth my Yaesu 857 directly to the car.

Post by **robbage** » Fri Sep 19, 2008 6:20 pm

Current project 95% finished, testing stage, for 2 metres. Basically a 5/8th GP modified to be collinear with two more 5/8 elements above. Is only about 1.5 MHz bandwidth for <= 1.5:1 SWR. Alleged gain is somewhere between 6 and 9 db over a 1/4 wave depending who you believe. I'll be happy if it's 4 or 5. The radials are a lot shorter than the design calls for and I have no idea why, but the SWR is about 1.15:1 for the required freq and doesn't improve much with longer ones. I no complain. SWR is crap for 70cm as expected although I managed about 1.55:1 at 433MHz some how. Made from 12mm & 16mm al tubing and SS radials, nuts bolts washers etc. And an N-type socket.

This is the test stand. It's a metallic extension pole for ceiling painting, 1.8m collapsed, 3.7m extended. You just twist each half to lock it. The base is a target stand with an old lead acid battery for weight

It was bloody windy the last couple of days.

Antenna in the 30kmph wind (and HV power lines in the background

) You can see the demarcation between the three elements which are 3/8 phasing coils. About 4.2 metres counting the section of mast above the radials.

Lower

Upper

Post by **RubberDucky** » Fri Sep 19, 2008 7:06 pm

robbage wrote: It's a metallic extension pole

Absolutely ideal for getting into those hard to reach places in between the HV power lines!!!!!