Saturday, April 11, 2009

Off to the HamFest, in the rain

Which in most other places wouldn't be that unusual, but this IS Phoenix after all.

Of course being a hamfest, I doubt the rain will bother folks much... If you don't know hams, it can be hard to explain; but basically they're like the post office. Neither rain nor snow, nor gloom of night can deter them from their Elmerish pursuits.

Anyway, I need a new antenna for my HT (a Yaesu VX-5R, 6m/2m/70cm TX broadband RX). The factory stock rubber ducky has a hard time hitting a repeater just 5 miles away with 5 watts, and that's just sad.

For the uninitiated, "my HT" refers to my hand held portable radio transceiver; a compact model manufactured by Yaesu (A.K.A. Vertex Standard) electronics in 2004 (they've come out with a couple newer models since and discontinued mine), capable of transmitting on the 6 meter (50mhz), 2 meter (144mhz) and 70cm (440 mhz) ham bands, and receiving signals on many more bands, above, below, and between the ham bands (like AM and FM radio, public safety bands, aviation bands etc...).

My particular VX-5R is also modified to act as an aviation transceiver; however as transmitting on those bands is unlawful for non-aviation purposes, I don't transmit on that band ever. I did the modification so that I could signal aircraft in an emergency.

Oh and why do they call them HTs? Handie-Talkie is what Motorola called the first one in 1941, and hams are... let's just be polite and say a conservative and traditional bunch. They were called HT's 68 years ago, they're called HTs today.

People have backronymed it to "Handheld Transciever" but that's just so they don't have to admit to being old fuddie duddies (even the young ones).

Seriously, I'm not sure who is more conservative, hams, or gun owners... of course there IS a pretty significant overlap....

UPDATE: Well, that was a bust. Apparently, it was quite busy... from 6am to 8am; but by the time we got there, most folks had already buggered off.

Thankfully it seems they buggered off all of 300 yards away, to the local Ham Radio outlet; and I was able to get a new antenna for the HT. Actually I picked up two: One zero attenuation mini stubby (a Comet SMA-501), and one Diamond high gain 1/4 wave whip).

Zero attenuation in this instance refers to the fact that the stubby little antennae has no attenuation (loss of signal strength) compared to an equivalent end feed 1/4 wave vertical antenna, on both 2m and 70cm (which means it is electrically the same as a simple wire antennae 19" long for 2m operation, or 7" long for 70cm). Not bad for an antennae less than 2" long.

High gain, in this instance, refers to the fact that the Diamond whip antenna exhibits increased signal strength as compared a plain wire 1/4 wave end feed. Theoretically this particular antenna has 2.15 dbi gain (slightly less than doubling of signal strength. Every 3db is an approximate doubling of strength) on 70cm, and 6dbi gain on 2m (approximately 4 times the effective signal strength).

Unfortunately, because of the inverse square law, an increase in effective strength only actually increases the range you can transmit or receive by the square root of the increase (and that's in a vacuum, not accounting for terrain, interference, or atmospheric attenuation). So a +3dbi gain, or doubling of signal strength, gives you about a 40% improvement in range; and a quadrupling of signal strength only gives you a 100% increase in range.

And of course, that's only the theoretical physics of it. The real world DOES include terrain, and atmosphere, and other such inconveniences, which dramatically effect your range. In the real world, a +3dbi or even +6dbi increase only gives you maringally more usable range; because although you get a lot more theoretical maximum range, the signal at that extended range is still too weak to be useful (it's called being below the noise floor).

The Diamond is one of the antenna models I was interested in and specifically looking for; and HRO had it (Actually both of them) for well off list. It seems like a significant improvement over the factory rubber ducky. I'm having no problem hitting several repeaters I couldn't hit before. 'Course, it is twice the length of the factory whip (more flexible though).

The stubby is very useful for local short range operations, like car to car in convoy; and it is only very slightly less effective than the factory rubber duck. Plus, it's TINY (1-3/4"), fits into small spaces and isn't likely to snag on anything or break off.

While JohnOC and I were driving over there, I discovered the PTT on my headset was dead, so I also picked up a new speaker mike (about half the price of a new PTT headset, and more comfortable to use most of the time anyway).

I also snagged the 2009/2010 repeater director, the Gordon West tech, general, and extra manuals for Mel and I to study (Mel is now thinking she at least wants to get her general), and the 9th edition operating manual (I only have the 8th edition). I figure 'tween all those, we should be good to go.