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#21
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Who is God?
"Generally" works "exactly"? You seem to be somewhat confused. "Tim Wescott" wrote in message ... Airy R. Bean wrote: I can assure you that it is not. However, if it makes you feel better then please deceive yourself on that matter as you undoubtedly do upon the religious beliefs of DSP. I will! Particularly since when _I_ build a system with DSP it generally works exactly as I've predicted it will. If I'm deceived, then so is God -- are you saying that God is deceived by how DSP works? |
#22
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Is this kind of inductors still for sale or still build ? I would like to
buy two identical roller inductors of about 20 to 30 µH for an antenna tuner. Does somebody know where I can buy them. In the US or in Europe, no matter. 73 de ON5MJ - Jacques. ====================================== These roller inductors can often be found at ham flea markets . Residing in Belgium you might have an opportunity to visit some of the many flea markets in the Netherlands . There is a really big one in March every year at Rosmalen near 's Hertogenbosch. Another one is the open air ham flea market at the 'Lichtmis' trucker's stop between Zwolle and Meppel (last Saturday of September). I have seen roller inductors for sale at any ham flea market in NL ,also new ones . Good Luck Frank GM0CSZ / KN6WH |
#23
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An old-timer I used to know made his own from plastic drain pipe. He used
a lathe for cutting a spiral grove in the pipe for the wire, and machined most of the other parts himself. ========================= Before using drain pipe check it for RF integrity in the microwave oven. The grey stuff seems to have metal containing pigment. The white stuff might be better .....suggest you always check. Another possibility might be a polystyrene cylinder in the shape of a liquid volume measuring gauge as used by photographers in the dark room . I have such a gauge made by JOBO - Germany , volume 500 milli-litre ,diameter 65 mm ( approx 2.6 inch), length 200 mm (8 inch). Frank GM0CSZ / KN6WH |
#24
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To do this I would use a 'blast from the past', a variometer.
This consists of two coils, one fixed and one rotating inside the fixed coil. If both are the same inductance (so the outer one is would with wider spacing than the inner) when they are in "series aiding" the total inductance will be the sum, plus the mutal inductance. When they are series opposing, the total inductance will approace zero. (over simplifcation). Variometers have NO moving contacts so they are easier to build than rotary coils. They can't be made as large in inductance without avoiding other problems (large distributed capacitance), but a small variometer in series with a multitapped coil is a good compromise. ======================== Don't know the US situation ,but in Europe the marine 2 MHz band (in particular 2182 kHz emergency channel) is no longer used, with most ships now having satellite comms. All that redundent equipment is now being dumped or made available via the surplus trade . They all have variometers. However these variometers are probably only usable up to 10 MHz. Recently I was given a low power life boat emergency transceiver made by SKANTI (Danemark) for operation on 2182 and 8863 ? khz ,fitted in a water proof enclosure ............beautiful components including a variometer. Skanti also made the wellknown Sailor marine radio ( painted green). Frank GM0CSZ / KN6WH |
#25
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In my case I can't have a look into the tuner or handle alligator clips as
the tuner must be remotable and outdoors. The shack will be soon located in the cellar and it will not be possible to pass the ladder line through the house. A coax would be rather acceptable indoors. So I am looking for a good solution for the inductors: roller inductors, tapped inductors, tapped inductors with small variable serie capacitors. Driven by servos or stepper motors. Maybe I don't need a fine tuning of the inductors because of the main variable capacitor could be enough. ========================================== Provided there is not too much metal around you can readily pass a balanced feeder 75 -300 or 450 Ohms ribbon through the house. I use a 'Doublet' 2x 21 metres with a balanced 450 Ohms ribbon feeder running into and over the loft and so into the ground floor shack with a balanced to unbalanced matching unit in the shack next to the transceiver . No RF(I) problems ! Max RF power 100W-PEP Frank GM0CSZ / KN6WH |
#26
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To do this I would use a 'blast from the past', a variometer.
This consists of two coils, one fixed and one rotating inside the fixed coil. If both are the same inductance (so the outer one is would with wider spacing than the inner) when they are in "series aiding" the total inductance will be the sum, plus the mutal inductance. When they are series opposing, the total inductance will approace zero. (over simplifcation). Variometers have NO moving contacts so they are easier to build than rotary coils. They can't be made as large in inductance without avoiding other problems (large distributed capacitance), but a small variometer in series with a multitapped coil is a good compromise. ======================== There's a serious shortcoming with variometers for transmitting purposes. As the inductance reduces the wire resistance remains constant. Result - extremely low Q for small inductances. ---- Reg, G4FGQ |
#27
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![]() Now I will try to find 4 stepper motors. I also got very good ideas from Bob (anonymous) about the use and control of stepper motors. =================== Good stepper motors for your job would be found in 'ancient' 8 inch floppy drives or the larger Hard Drives . Frank GM0CSZ / KN6WH |
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