VK3RGL 2m Beacon

[VK3PY]

Today, David VK3QM and I completed the replacement of the 2m yagis on the Mt. Anakie 2m repeater, VK3RGL (QF22DC). The old yagis were some 10 years old and one was looking a little sad. I thought it worthwhile to post some facts relating to this beacon.

The 2m beacon transmitter delivers 18W into the feed line, which after a small amount of line attenuation and 2-way power division leaves 7.5 watts into each of two yagis. One yagi ("West") is aimed at 293 degrees. The other ("North-East") points at 32 degrees. Each yagi has 8dBd gain (according to Yagi Analyzer, on which the design was produced) and a -3dB beam width of 50 degrees. Their -8dB beam width is 84 degrees. Even at the latter beam width, the beacon's ERP equals what it would be with a simple Omni antenna such as a halo or crossed dipoles (in the latter case, it would be running twice the power into a -3dBD antenna). I will leave readers to plot the beacon's coverage on Google Earth.

The 70cm beacon has its two yagis similarly oriented, these being 5-element designs of about 8.5dBd gain and therefore slightly narrower beam width. A significant difference with the 70cm beacon is that unlike the 2m beacon which transmits simultaneously in both directions, it switches directions at approximately 15-second intervals, announcing the direction with either "W" or "NE" at the end of its calls sign, as appropriate. Its output power is also significantly higher at 15W into each yagi.

I doubt that anyone will notice any difference in the 2m beacon's signal since its old antennas were still quite functional. However, reception reports are always welcome.

Chas
VK3PY

[VK2ZRH]

Altogether an intelligent implementation of intended beacon coverage.

[VK2KRR]

Thanks Chas

To me it currently seems the (2m) signal is better than usual. I might need a little more time to see if its being assisted by conditions or not, but so far it seems good.
Of late, maybe the past year or more even, Ive noticed the signal from the VK3RGL 2m beacon has been quite poor most of the time. A slow degredation perhaps over the years, as it used to be quite good. It was to the point where I often didn't really bother to look for the signal due to how bad it was.

So perhaps this has done the trick as its currently sitting on S9+10dB relatively stable. Its being knocked about by aircraft multipath fading at times, but once they go away its fairly stable and strong.

I'd suggest others may well find it better to the north and north east now. One person who would be good to get a signal report from would be Rob VK1KW. I think Rob had also noticed 2m was poor compared to 70cm.

Thanks for your efforts, its a great beacon.

Ps. 1296 beacon please

[VK3PY]

Thanks for the report, Leigh. As it happens, it was the NE facing antenna that had weathered rather badly. It is quite possible that water has got into the gamma match of the driven element. I'll need to take a closer look at the "wreckage" to confirm this. Chris VK1DO had mentioned to me on several occasions in the past that he suspected the beacon's signal was poorer than it used to be. However, there was no indication from within the "shack" that anything was awry. Antenna match was OK, output power good etc. But I was aware that the yagis had reached their "use-by" date, so I built another pair to replace them when time permitted.

The two new yagis are a little more robustly constructed this time, with better weatherproofing. Time will tell. I do value reports, good or bad, as I believe there is no point in having a beacon unless it is reliable and functional. Otherwise, as you quite rightly point out, Leigh, you stop looking for it. Apart from mains power failures or occasional short shut-downs for site maintenance, last week was the first time our 2m beacon was off air for at least a decade.

Chas
VK3PY

[VK3AMZ]

Hi Chas

No difference noted here........ 59.....LOUD

Appreciate the effort from both you & David (I'm sure Ken's handy work is in there as well) . I can testify that both beacons have been ON for a very long time.

Cheers