Archive for April 2007

Bruce Miller Nursery

April 29, 2007

I believe this is the fourth gardening post this spring. I also think it is the most important of the four.

Recall our disappointment at the high prices at Calloways in Plano. Maybe you don’t recall. Well drive up to Plano and look. You will see what we mean.

Those prices were so high that we thought we were getting a super deal at the A&M plant sale where we were only charged two bucks a plant.

The home improvement centers were mixed blessings. I just find it difficult to justify paying more than one dollar each for annual bedding plants.

Last week we received a 15% off card in the mail from Bruce Miller Nursery. My first thought was to ditch it but it re-educated me that their closest place of business was only a mile or so down the road.

Yesterday afternoon we gave Bruce Miller Nursery a visit. Not only did we get 15% off the asking price but the asking price was significantly lower than even the stuff we saw at the home improvement center. To top that off, their plants looked better than any we had seen anywhere this season.

A flat of 18 fairly large (3 inch pots), well established, plants for $14. Or $11.90 with the 15% discount. That comes to about 66 cents per plant and they looked every bit as good as the two dollar variety we bought at the A&M plant sale. To be honest the two dollar plants were in a larger pot, but three inch pots at 66 cents each are the best deals we have found in a long time.

Bruce Miller

Click on Bruce Miller above to get to their web site. Don’t expect too much on their web site. I was expecting pictures of plants with prices but did not find any. I had to go to their business location to find those. Well worth the trip.

Yes, their geraniums look just as good in real life as they do in that picture on their web site. Only Five bucks a plant. We got two.

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4X811

April 26, 2007

Finally got the tube sockets ordered for the new 811 amp.

Soon there will be a pair of 4-400s with sockets and blower available for more serious amplifier duty in someone else’s shack.

We will be using four 811s along with our 1500vdc one amp HV supply.

The linear will still be larger than it needs to be and rack mounted but it will also be a little better behaved without the noise from the blower to modulate the airwaves.

The conversion should be fairly easy. Just pull the tubes, sockets, blower, build a bias supply, add a low speed fan, and find a 16 amp 6.3vac filament transformer. Need to check that again but the last time I looked an 811 needed 4 amps at 6.3vac for the filament. Man!, that is 100 watts just to light the tubes!

No way am I going to buy that kind of iron new or used. Good thing I saved those 24vac 4 amp utility transformers. Looks like one of them is going to have its secondary rewound for 6.3vac. Shouldn’t be too hard. About six turns is all it will take.

Rain

April 26, 2007

We have come to a new appreciation of rain. We have not had enough of it in the recent past. Minor drought conditions have prevailed.

This week we got plenty of rain. Although we only recorded about two inches, parts north of here got as much as ten inches.

Spring rains are important. April showers bring May flowers. Or so the saying goes. Rain also conditions the ground. Not just the flower beds but the yard as well. A wet yard makes weed pulling easy.

Sure, we can use a herbicide but that might also kill the flowers and the grass. Besides, it costs money and it might not be all that friendly to humans either. It is much more pleasant to sit on a green lawn, enjoying the fresh air and sunshine. It is particularly enjoyable when the ground is wet enough to permit pulling weeds, roots and all.

Resonance

April 22, 2007

Resonance is the condition where the antenna displays a resistive load of predictable value at the frequency of interest. You get there by cutting a dipole to a half wavelength, breaking it at the center and attaching a feedline there. Then raising the whole mess in a flat top configuration a certain distance above electrical ground.

This is what is called a resonant antenna. Its resistive load is generally 75 ohms. Its height is at least one quarter wavelength above ground (or multiple thereof). Under those conditions its SWR is very close to 1:1. It will absorb all the power you feed it as long as the feedline is also 75 ohms and your radio has a 75 ohm output. Such an antenna will also provide the maximum in signal on receive.

A non-resonant antenna requires an antenna tuner. The antenna tuner adjusts the antenna system and brings the non-resonant antenna into a resonant condition. That resonant condition may or may not be 75 ohms resistive. Most commonly it will be higher than 75 ohms and that condition will be handled with open wire line, window line, or twinlead down to the antenna tuner. The SWR on the feedline may be much higher than 1:1 but that is okay because there is very little loss in open wire line. SWRs as high as 10:1 can be allowed without adverse effects as long as open wire line is used.

The antenna tuner will match the higher, resonant impedance to the radio. It will also ensure that the non-resonant antenna behaves as a resonant device in combination with the tuner to form a resonant antenna system.

Depending on the choice of antenna and tuner this is a nice way of providing coverage over the entire HF bands with one antenna system. You end up with a true multiband system where the system only works on one frequency at a time. The frequency to which it is tuned. Untuned multiband systems are tuned to multiple bands at the same time and may result in undesired radiation of harmonics. Such complications are avoided in tuned systems at the cost of requireing tuning.

Full Circle

April 22, 2007

I went from antenna tuner to resonant dipole fed with coax and now back to non-resonant dipole with antenna tuner again.

Getting the thing tuned up on 75 meters this morning I re-discovered a neat property of non-resonant antennas. They are completely deaf except for the frequency to which they are tuned.

I had this thing tuned to 40 meters. I switched to 75 meters and the receiver went dead. I mean dead as a door nail. Nothing whatsoever. Not even that reassuring crackle of static that you hear when connecting an antenna to the input. It was nearly as though I had pulled the speaker plug. In fact, I did check the speaker plug just to make sure that had not happened.

Once I got the antenna tuned to 75 meters and the receiver peaked for that band, all was well again. Lots of signals and some noise.

So once again I am appreciating the frequency discriminating aspects of an antenna system that requires tuning. All those possibly interfering signals on unused bands that were present with the all band antenna system are gone now. I now have a very selective tuned circuit right at the antenna. In fact, it is the antenna and provides a very nice preselector function.

This got me thinking about resonance and what it means.

Imagine That

April 22, 2007

Not sure how this happened but for some reason I disabled the cookie function in my browser last night.

Today I found that I could not log on to my blog. I entered the user name and password but instead of allowing me access, I got the login page again with blank user name and blank password.

Took a while to figure out what was going on. Had I not remembered disabling the cookie function I might still be fussing with the thing.

Now I need to see what it was that made me decide to disable cookies in the first place. Must have had something to do with unwanted ads.

Gardening 2007

April 15, 2007

This years season started out as every other season. We made the rounds. First to a real nursery. Then to the home improvement center. Then back home to plant our purchases.

As usual the nursery was still specializing in annuals and high prices. On the way back from the nursery we passed by the A&M center on Coit and saw a sign advertising an A&M plant sale. We turned around and headed back to the sale.

They were nearly sold out but we still found enough to cost us nearly 40 dollars. Not complaining. Their prices were about half what the nursery was asking. We found some tomato plants, pepper plants, dwarf zinnias, and some very nice lantana.

oldlantana.jpgWe had bought some lantana years before at the home improvement center. It was yellow and took over the entire flower bed. Later we moved it to a side garden where it did not seem so out of place. It dies off in the fall but comes back in the spring. This spring is no exception. There are six very nice sized clumps of the stuff coming up just like they did last year.

newlantana.jpgThe new lantana has leaves that are a deep green and flowers that are deep red. It should go well amongst the yellow stuff we had planted earlier. Although there are only four of the new plants, we expect they will do well, grow quickly and rival the yellow lantana already established.

We still stopped at the home improvement center (handy homers, I call it). The plant section was somewhat of a disappointment when compared to the A&M plant place but we did find an 8 by 4 foot section of 3/4 inch oak plywood that followed us home.