Sunday, June 23, 2013

ARLHS IDO-061 Damar Besar/Edam (Java) Lighthouse

Damar Besar/Edam (Java) Lighthouse

Pulau Damar Besar {Edam}
1881. Active; focal plane 55 m (180 ft); four white flashes every 20 s. 50 m (164 ft) 12-sided cast iron tower with lantern and gallery. Entire lighthouse painted white. Deni Adam Malik's photo is at the top of this page, a portfolio of photos and another photo are available, and Google has a fuzzy satellite view. Staffed by a crew of five. This famous lighthouse traditionally welcomes travelers to Jakarta. It was prefabricated in the Netherlands by Nering Bögel, Deventer. Located on Pulau Damar Besar in the center of the entrance to the bay of Jakarta. Accessible only by boat, but apparently boats can be chartered in Jakarta. ARLHS IDO-061; Admiralty K1062; NGA 23404.

Further out, about 17 kilometers from shore and right in the center of the semicircle described by Jakarta Bay, lies Damar Besar island. Known by the Dutch as Edam, the island takes its current name from the fact that a lighthouse stands on it: damar means torch and is also the name of the combustible resin that oozes from certain tropical trees. The lighthouse currently standing at one end of the island was built from a standard kit of iron parts shipped out from the Netherlands. This one was assembled in 1879 and there is an identical one at Anyer on Java's west coast of about the same age.

The lighthouse keeper will happily let visitors climb to the top of the tower (225 steps) in exchange for some lunch money. (Not that there is anywhere to buy lunch -- you have to take your own.) From the tiny iron walkway at the top of the lighthouse, you look down over a dense canopy of secondary forest, from which the calls of birds and cicadas drift up. The boat at the landing stage lies far below. Unfortunately, it was not a clearday and the blue-green sea receded into a gray haze past the skeletal fish traps and scores of fishing boats.

Most of the island is occupied by dense secondary forest, but this was not always the case. If you wander around the paths between the trees, you will come across two Japanese gun emplacements from World War II. One assumes the forest was cleared at that time for visibility. Now, the humid silence of the jungle shrouds these solemn reminders of past conflict.

There is also a group of graves, one holding the remains of Ratu Syarifa Fatima, the wife of Banten sultan who died on the island in 1751, having been ousted by the people of the historic port city west of Jakarta. At that time a splendid mansion stood on Damar, built by Dutch governor-general Camphuijs. It is said the foundations still remain but you will have to search for them. The English did a pretty good job of destroying the house in 1800.

Decades ago, there was a ""resocialization center"" on Damar. It seems the idea was to get criminals and other undesirable elements of society together and try to teach them better ways. To us today, it sounds more like a ""send-them-offshore-and-let's-forget-about-them center"". These ruinsstill remain: tall rooms stand ceilingless, cement rots slowly and the jungle steadily asserts its grip.

After a look around Damar, it is highly recommended to take the boat out a little way and dive in. The water on the day we went was crystal iridescent turquoise. Irresistible.


Wednesday, June 12, 2013

Home Built Buddistick Antenna

Home Built Buddistick Antenna

W3FF made the original instructions on building a home built Buddistick. He commerically manufactures the Buddipole and Buddistick. This is the Buddistick that I made. It was built similar to the instructions but I changed a few things. I didn't use the speaker wire, I used # 14 enamel wire for the coils and inside the bottom tube. The top piece I made from 1/2" PVC and drove a 3/8" X 24 coupling into the 1/2" PVC (it makes a tight fit). If you use the alternate whips I would do it differently (see below). Down Load the complete instructions below.

I made the bottom pole first. It is made from 3/4" PVC sch. 40, 26" long. I drilled a small hole 1" from the top and bottom (only through one side of the pipe). I then put in a # 14 enamel wire inside the pipe and put the wire out through the holes. The bottom wire only needs to be 1" but the top will need to extend out about 6". On the bottom I drill two holes (at right angles to one another) for 6 / 32 bolts (one of the holes need to be close to the wire). Insert the bolts and nuts. Scrape off the enamel off the bottom wire and secure it to the bolt closest to it (I soldered a lug on mine). Place a second nut to hold the wire onto the bolt and then place the Wing nut on the bolt. On the other bolt place a Wing Nut on the bolt (this will be used for the coax shield and Radial).

Cut the coil forms according to the chart below (use 3/4" PVC). Drill a hole all the way through the PVC (this should be a tight fit for the # 14 enamel wire) 1" from each end, the holes should be oriented the same way. Push one end of the wire all the way through the pipe leaving about 6" exposed. Wind the number of turns indicated in the chart below and then push the end all the way through the pipe to secure the coil.

Whip Mounting Detail 9 1/2' Whip w/3/8 X 24 Thread

Alternate Whip Mounting Detail 72" Whip w/1/4 X 20 Thread

Mounting the antenna, I put a 3/4" plug into a coupling (slip on one end for the plug and threaded on the other end for the antenna) and mounted the assembly on a spring clip. I can then place the spring clip on a table etc. It works good up to ~ 1" table, if thicker it will then lean to one side. I'm working on a different mount.

Attach the Radial and Coax, the Radial is an elevated Radial, it doesn't touch the ground.

Using the above chart as a starting point, hook-up your antenna analyzer and find the lowerest SWR. If the frequency is high then you will need to lenghtened the radial, etc.

If you don't have an antenna analyzer then you will have to use your SWR meter on your radio or tuner. To get the approximate setting for your tuner tune for maximum noise and then check the SWR.

Whip Mouting Detail 3/8" X 24

Buddistick Components Whip - Coils - Bottom Pole - Clamp

Buddistick Antenna Top Section

Buddistick Antenna / Bottom Section 10M, 12M, 15M, 17M Configuration

Buddistick Antenna / 40M Coil / Bottom Section

Operating & Tuning - Home Made Buddistick

I did an analysis of the Buddistick that I made. The radial lengths are different than what was published in the article as I built mine a little different. I corrected the table above. I used EZNEC to model each configuration. Below are the results, showing the SWR curve for each band. It is based it on a height of 4' (off the ground) for the Buddistick and 1' at the end of the radial. The radial has to be above ground. 

10 M SWR Curve 
12 M SWR Curve 

15 M SWR Curve 
17 M SWR Curve 
20 M SWR Curve 
30 M SWR Curve 
40 M SWR Curve 
60 M SWR Curve


Tuesday, June 11, 2013

10M Vertical Antenna

10M Vertical Antenna

After reading an article by N2UHC on a 10M vertical dipole I decided to build my own. The antenna in the article was made from electrical conduit. I had some problems with the electrical conduit as it was very hard to tune. I have built several of the Copper Cactus 2M antennas and have also been building EH antennas, so I decided to use similar building methods and material for my 10M vertical dipole (copper pipe and PVC pipe). I used 3/4" copper pipe for it's rigidity and the 1/2" copper pipe allows for adjustment. I began by modeling the antenna using EZNEC. I decided to mount the antenna close to the ground. This gives the antenna a low angle of radiation. You can notice that you have a decrease in the gain but I think the low angle of radiation will make up for the loss in gain.


3/4" X 10' Copper Pipe Lowe's / Home Depot
1/2" X 10' Copper Pipe Lowe's / Home Depot
1 1/2" PVC Sch. 40 Pipe Lowe's / Home Depot
3/4" X 1/2" Copper Pipe Reducers Lowe's / Home Depot
# 8 or #10 X 1/2" Sheet Metal Screw Lowe's / Home Depot
SS Hose Clamps Lowe's / Home Depot
With the price of copper, you might want to use alumunim tubing.

Start by cutting the 3/4" copper pipe in two 5' sections. On one of the section mark 1', 2', and 3'. At the marks drill a 3/8" hole through the tubing on one side. All the hole should be lined up. On the other section mark at 6" and 1' and drill 3/8" holes through the tubing on one side. These holes will be used for mounting the copper pipe to the PVC pipe.

The 2 reducers have to be modified. Using a hack saw cut a groove in the 1/2" end down to the 3/4" section. This will give the hose clamp room to compress the reducer and hold the 1/2" pipe. Now on the inside of each reducer you will find a little tit. This is used to stop the pipe at the correct location when inside of each reducer you will find a little tit. This is used to stop the pipe at the correct location when Solder the reducer onto the 3/4" pipe. On the section that has two holes, solder the reducer on the opposite end.

Cut the 2 - 3' section of the 1/2" copper pipe. This will be used for the ends of the antenna. Slide the 1/2" pipe into the reducers leaving about 2' exposed and secure using the hose clamps. Lay out the PVC pipe and the two sections of the antennas. The spacing between the two sections should be approximately 1". Drill a hole through the other side of the tubing where you have the 3/8" holes. This hole should be sized so the sheet metal screw will rotate freely. Now place the copper pipe and PVC pipe according to the drawing. The PVC should extend approximately 14" above the center of the dipole. Using a 1/8" drill bit drill through the hole in the copper pipe into the PVC. Fasten the copper pipe to the PVC pipe using the sheet metal screws. Now mount the coax to the antenna. The braid of the coax should be on the section closes to the ground. There are many ways to connect the coax to the antenna (using screws, soldering, etc.). Mount the antenna using the PVC pipe. Mounting solutions is up to you. The antenna may be tied down with non-conduction rope. This will give it more stability. After mounting the antenna, connect it to your rig and tune the short pieces (1/2") to obtain the best SWR. As can be seen from the SWR plot the 2:1 bandwidth is over 1 Mhz.

6M Vertical

Make a 6M vertical dipole using the same model except the 3/4" pipe sections are 3' long and the 1/2" pipe section are 3' long with 1 1/2' exposed. Antenna would be ~ 2 1/2' above ground to 11 1/2'. I started with the antenna at 2 feet above ground similar to the 10M antenna but after tuning the 1/2" copper pipe ended up being 1 1/2 feet instead of 2 feet.