Re: Hey BMJ....



On Mon, 2 Nov 2009, BMJ wrote:

Me wrote:

<snip>

The homebrew Buddipole consists of a pair of telescoping whip antennas and some hand-wound coils, but no capacitors. All one has to do to tune it, in theory, is to adjust the length of the whips and use the appropriate coils.

The "capacitors" are the whips at the end. By making them longer or shorter you increase or decrease the capacitance and thus adjust resonant frequency.

I was thinking about capacitors used like a T or gamma match.

Yes, but every piece of electrically conductive metal, no matter what form, etc., has some capacitance and inductance, depending on that form.



But, you can always go out and buy an automatic tuner and play "spoiled brat" like all the other spoiled brat non-macho, quiche-eating dweeb-geeks.

One reason I consider using a tuner is that I could set up my antenna, tune it properly with my antenna analyzer one day, set it up again to the way I had it before another day and the SWR's gone to pot because a neighbour put something out on the balcony. All of the settings I had from before wouldn't be any good.

At least with a tuner, I might get some consistent settings, considering that in my neighbourhood, there are lots of things which could affect an antenna's performance. Personally, I'd rather tune it by hand without any other added hardware.

It should not affect tuning that much unless you get something very close to the antenna.

It could be that the kids living right above me at the time stored some junk on their balcony that wasn't there before.

One can only make speculations if you can't actually know everything going on around you for a radius of, say, 10-20 feet.

They were a bunch of slobs who weren't particularly concerned about being good neighbours. They frequently tossed their cigarette butts over their railing, so guess where many of them ended up. They weren't the swiftest bunch and made Beavis and Butthead (or, here in Canada, the Trailer Park Boys) look like Mensa.

Yeah, I read about these clowns in my local newspapers, too.



Don't worry too much about SWR. Anything up to 2:1 is really not hurting your rig or, significantly, your signal. A 3:1 SWR means you might be losing 25% of your power (depending on feedline length) which is something like 2 db and it would be difficult for anyone to really notice that without instruments. Bars on bar-graph indicators on FM transceivers are probably more like 4-5 db and I rarely hear any difference if guys up or down their power level, unless they are really "in the noise" to begin with.

I understand that part, but what drove me up the wall was when, despite following the designer's tuning instructions and building the antenna as close as possible to what he had, I couldn't get the SWR down below 5 on some bands.

Sounds like a problem.

For one thing, I didn't have all the materials exactly as the designer called for, largely because some of them aren't available up here. I had to compromise, so there might be a few things wrong with what I built.

Yes.

Lots to work on....


I talked about it with another local ham who built one himself and he was similarly frustrated. A tuner, though it may be the easy way out, might overcome some of those problems. I got the idea from a newsgroup I subscribe to, so maybe the person who suggested it has some further comments about it.

Or, you didn't build it quite right.

The original suggestion was an automatic tuner, but I found a manual unit made by MFJ which might work for me. I won't need an extra battery for it (which means less weight in my backpack) plus it's designed for mobile service and it works on 6 m.

I bought a manual tuner at a flea market last year, but it only goes up to 30 MHz.

Kenwood, at one time, made a specific tuner for 2 meters, and I bought one with the idea of antenna experiments without a gamma match.


On the other hand, I cobbled together a 2 m dipole using a set of rabbit ear antennas. I got the idea from an article in a ham magazine where the design called for some leftover whips from dead radios. Since I didn't have anything like that handy, I bought the rabbit ears from a nearby store and tried it out a few times without checking it with my antenna analyzer. I worked some local repeaters and checked in with a 2 m SSB net. It seems to work.

Keep it.

I intend to. I want to have a variety of antennas to experiment with. I've got a number of verticals that I can use with either a magmount on my car or with a ground plane kit.

OK

<snip>

Problem for me is that my CW code speed
just never gets much faster than 8-10 wpm then I start making errors and that's no fun.

I can copy at least 12 WPM and I'd like to push it towards 20.

I wish I could be there. At 12 wpm, I start missing about 10% of characters.

I sometimes do that, but I often fill in what's missing if I've copied enough.

<snip>


OK
.

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