Month: August 2011

Autumn Antenna Plans

Dave Mueller

Autumn on Guam brings a continuation of the rainy season, but the temperature maintains the constant year-around tropical heat. Shorter days in the northern hemisphere bring better conditions, and the start of the contest season.

There are a number of projects I would like to tackle over the next month to prepare for the Oceania DX contest, CQWW DX, and other fall/winter contests:

(1) I need to renew my African Beverage wire. I made the mistake of stringing the receive antenna with white insulated, stranded #16 wire. The stranded wire caused it to stretch and sag, and the wild pigs chewed the antenna to pieces, thinking the white insulated wire were grubs or worms (food). I ordered 700ft of #18 copper clad steel wire, the same material I use for my other three Beverages which have been reliable for the last year since they were installed.

(2) Relocate my 40/30m dipole. Right now, my 40/30m dipole is located on an extension above my Spiderbeam, placing the feed point at 50ft. Relocating the antenna to a nearby coconut tree will lower the center by a few feet, but reduce the stress on the rotator. I’m worried it may fail in wind due to the lever action of having 15ft of mast sticking out the top. Also, I am worried about interaction between the 40m dipole and nearby vertical, as well as interaction with the Spiderbeam on 15m.

(3) Raise the Spiderbeam a few feet, from 35 to 40 or 42 feet. Once the 40m dipole is moved, I feel I can get the beam up a few feet higher by telescoping one more piece of pipe at the base (2.5″ at the bottom instead of 2″ that I have now). I’ll need my son to help raise it into place, but that 5-7 feet should be beneficial on 20m, even if only to satisfy my mental thoughts of being louder.

(4) Install phased verticals for 40m. I have room to install a 2nd 40m vertical and phase them toward EU, 90 degree spacing 90 or 135 degrees out of phase (I’ll probably use the Christman method of feeding with 90 degree phasing). The house will effectively block the takeoff toward NA and SA, so I will need to keep the dipole for those directions, but phased verticals should give me some additional gain to try to break through the EU “wall” on 40. Relocating the 40m dipole will help minimize interaction which would make the array ineffective if left in its current location (according to EZNEC).

(5) Renew my 80/160m support mast. The mast is a bit floppy at the far end, and it got tweaked during the recent nearby formation of Tropical Storm Talas which brought higher than normal winds to Guam. I don’t think I can extend the mast any longer, but I need to make it more rigid.

(6) Better SO2R isolation. I need to better configure my shack for SO2R, with the addition of W3NQN type bandpass filters and a new 2nd radio antenna. This 2nd radio antenna (for 40-10m as I can use 80/160 already with the 2nd radio) will probably only be a dipole or other simple temporary antenna, but greater separation by placing it behind one of the vacant next door houses should keep me from blowing up any more front ends.

These projects should keep me busy during the month of September!

My current 40/30m vertical which will make up one of my phased 40m vertical array. The 80/160m TEE is in the background.
Current configuration showing my Spiderbeam and 40/30m dipole that will be relocated to prevent interaction and overloading of the rotator

 

CQWW CW comparison AH2R & NH2T

Dave Mueller

One nice thing about open logs in the CQWW DX contests is that you can compare with your local competition to see where you excelled, and where you need to improve.

For the 2010 CQWW DX CW contest, the AH2R team entered the M/S category, while I was SOABHP. The final results just came out; our final scores were very close, within 100K points.

The AH2R team operates from a hotel in the tourist district. The hotel is set on the hillside, overlooking beach front hotels. The view (and takeoff) to the West is remarkable, and they have a great shot to Europe and JA. Their shot to North America, however, is very unremarkable. The have monoband yagis for 40-10m, along with phased 80m verticals and a 160m vertical installed on the roof for the contest weekend only.

On the contrary, my station is much smaller. I have a pretty good takeoff to Europe and JA also, but nothing like the drop off at AH2R’s hotel. My takeoff to North America is better than AH2R’s, but nothing to brag about. My station is smaller, with a Spiderbeam up 35ft, 40m dipole, 40m vertical, and 80/160m TEE vertical.

NH2T hourly QSO rate
AH2R hourly QSO rate
NH2T continental breakdown
AH2R Continental breakdown
NH2T QSO Summary
AH2R QSO Summary

The above screen shots were taken from UA4WLI’s SH5 log analysis software. I highly recommend it.

A few things are telling from the analysis. I ended up with nearly 500 more QSOs than AH2R, and that’s even with 4 hours of off time. I suspect this was because of a number of reasons. First of all, I spent more time focusing on North America. I QSYed to 15 early both mornings to catch the East Coast opening, while AH2R chose to focus on working EU on 20 (and catching more multipliers). Likewise, I went to 40 and 80 early, before sunrise in Eastern NA, while AH2R stayed on 15m longer to catch the end of the European opening. The USA can not work each other for points, while Europeans can, so I preferred to focus on rate and run the USA when possible since I did not have to compete with continental QSOs.

Something I failed to mention previously is that AH2R suffers from being in a high noise environment. Being located in the tourist district means they have to listen to all the neon lights and other noise generators downtown. When pointing toward NA, they are beaming directly into the N/S main power line feeder on Guam and an industrial area with high noise. On the contrary, I live 2 miles north of AH2R, and have a very quiet QTH. My US Navy housing area has underground utilities, and my unit is located along the fence line with nothing but jungle to my north. During marginal openings, I suffer with smaller antennas but benefit from a quiet location.

Finally, I am very active outside of contests. I think that many underestimate the benefits of being active. Callsigns are more familiar to me, which helps increase the rate. I know that 9HP is probably YO9HP for example. This activity not only helps me recognize calls, but also understand propagation. It looks like I caught a great sporadic E opening to JA on 10m the 1st day that AH2R largely missed, rewarded with big rates.

My secret weapon are my Beverage antennas. I now have four, covering SA, NA, EU/JA, and AF. These receive antennas are extremely effective, and as a result I thoroughly trounced AH2R on 80 and 160m. The gentlemen at AH2R told me after the contest that they were frustrated listening to me run EU on 160m that they could not hear.

It looks to me, following this comparison, that my weak areas are 40 and 20m. During the contest, there was a two hour window both days, from 0300-0500 both mornings (local time), when I could not work anything. AH2R maintained rate during these hours; I took them off. This 03-05 local time window is during EU sunset, when they are busy working each other. This forms an effective wall that is hard to break through, and attempts to run are thwarted by key clicks and guys taking the frequency. AH2R was much more effective in running EU on 40m with their 2el yagi, so this is one aspect where I can try to improve my station. 20m is also a difficult band for me, with my antenna up only 35ft.

Coconut tree antenna supports

Dave Mueller

You know those days, when nothing seems to go right? Today was one of those days for me.

All was going fine, and I pulled into the driveway after work looking forward to a bike ride, since it was overcast and not too hot. Then, I noticed that one end of my TEE 80/160m vertical had come down. This explained why I felt weak last night on 160m when working W5XZ and trying to work TI5XP.

Coconut trees are the tallest things around my house, and I use them for antenna supports. Specifically, I use two ~40ft trees as supports for the end of my TEE vertical. The problem with coconut trees are that they have no branches. A line over the top will eventually fall out as the tree drops fronds as it grows – which is exactly what happened to me.

No worries, I got my fishing pole and heavy sinker to heave a new line over the tree. First throw – I miss to the right. Second throw – to the left. Third throw – I hit the tree trunk and the weight falls to my feet. I start getting frustrated. More throws are unsuccessful. I finally get the weight over the top of the tree – but the wind carries the fishing line off to the right and I miss the top all together. Next toss – somehow the line got wedged in the spool and the line goes no where – but the weight – one of my sockets – goes flying never to be seen again.

I get pissed – and throw the fishing rod – which promptly snaps in two. The handle even breaks off the reel so I can no longer use it. Now what?

Fortunately I have a recurve bow – but no arrows. I quickly make an arrow out of a length of 1/4″ aluminum tubing. After a few tries, I finally make the perfect shot over the center of the tree. But the “arrow” does not fall to the ground, and hangs 25ft in the air.

No worries – I go get a length of aluminum tubing, one of my old verticals. I reach up – and find myself 3ft short of the “arrow”. Really? Can nothing go right?

I grab more aluminum and lengthen the pole. I finally get the “arrow” down and pull the end of the vertical back up. This 30 minute project turned into a 3 hour affair, and now it is too late for that bike ride. But hopefully now I am louder on 160 – now that one end of the TEE is 6 inches higher in the tree.