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I read in sci.electronics.design that Reg Edwards
wrote (in . com) about 'Say what you mean.', on Sat, 26 Feb 2005: The best I could do is ask what is the S22 of a 6J5. One thing for certain, it is not mentioned in manufacturer's data sheets. Yet ARRL simple PA design rules manage very well without it. You wouldn't expect to use scattering parameters for a 6J5. But change that to 7194 and the question is not so facetious. (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. The good news is that nothing is compulsory. The bad news is that everything is prohibited. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
In article , Cecil Moore wrote:
Ken Smith wrote: At the point where it fails, the output goes to zero, I assume. If so, wouldn't that be the impedance as I've been defining it. Is an amp that fails at one minute with 100w FM better matched than an amp that fails at two minutes with 100w CW? No, you've got the concept backwards. Obviously the worst matched is the 1 o=minute case, next would be the 2 minute case and so on up to one which runs for about its MTBF at the connected load. This last case would likely be the one the designer was targeting. -- -- forging knowledge |
In article ,
John Woodgate wrote: [...] If the FM is what passes for music these days, it's MUCH better IMHO. There is very little that is sent in the form of radio waves that is worth the electrical power to send it. The really sad thing is that much of what is send via FM is really "voice grade" material. When FM was new, the material for FM was specially produced to take advantage of the wide bandwidth and large dynamic range. -- -- forging knowledge |
In article ,
Jim Thompson wrote: [....] But I vaguely recall a 5/8 wavelength antenna that had a good low-angle pattern. Unfortunately, the OP (is he still here?) was stuck with a box to short to even fit a 1/4 wave whip. I also think that this box could not be assumed to be resting on the ground If you squint at the ASCII art below, you will see more or less the radiation pattern of a 5/8 whip over a large ground plain. ................................. .................!............... ...........******!*****.......... ..........*......!......*........ ..........*......!......*........ ...........****..!..****...A..... ........*******..!..*******...... .....***.........!.........***... ...*.............!.............*B ******************************** If you don't have a large enough ground plain, the notch in the side labeled "A" starts to go away and the peak at "B" reduces. -- -- forging knowledge |
On Sun, 27 Feb 2005 17:52:52 +0000 (UTC),
(Ken Smith) wrote: In article , Jim Thompson wrote: [....] But I vaguely recall a 5/8 wavelength antenna that had a good low-angle pattern. Unfortunately, the OP (is he still here?) was stuck with a box to short to even fit a 1/4 wave whip. I also think that this box could not be assumed to be resting on the ground If you squint at the ASCII art below, you will see more or less the radiation pattern of a 5/8 whip over a large ground plain. ................................ ................!............... ..........******!*****.......... .........*......!......*........ .........*......!......*........ ..........****..!..****...A..... .......*******..!..*******...... ....***.........!.........***... ..*.............!.............*B ******************************** If you don't have a large enough ground plain, the notch in the side labeled "A" starts to go away and the peak at "B" reduces. -- The rain in Spain falls mainly on the plain ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
Still here, not quite sure who to believe, but enjoying the ride :-)
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On Sun, 27 Feb 2005 17:12:46 +0000, Ken Smith wrote:
In article , John Woodgate wrote: [...] If the FM is what passes for music these days, it's MUCH better IMHO. There is very little that is sent in the form of radio waves that is worth the electrical power to send it. Hmm, many advertisers would disagree. Since they have real money at stake and you don't... The really sad thing is that much of what is send via FM is really "voice grade" material. When FM was new, the material for FM was specially produced to take advantage of the wide bandwidth and large dynamic range. Bandwidth, perhaps. Wide dynamic range? The FCC rules seem to suggest otherwise. -- Keith |
On Sun, 27 Feb 2005 10:16:19 -0700, Jim Thompson wrote:
On Sun, 27 Feb 2005 17:08:23 +0000 (UTC), (Ken Smith) wrote: In article , Cecil Moore wrote: Ken Smith wrote: At the point where it fails, the output goes to zero, I assume. If so, wouldn't that be the impedance as I've been defining it. Is an amp that fails at one minute with 100w FM better matched than an amp that fails at two minutes with 100w CW? No, you've got the concept backwards. Obviously the worst matched is the 1 o=minute case, next would be the 2 minute case and so on up to one which runs for about its MTBF at the connected load. This last case would likely be the one the designer was targeting. -- It's been thirty years since I "hammed". I was only interested in the electronics, not the talking, so I dropped out after I got a homemade solid-state 2-meter rig running. I did the same after putting together a HF setup. The electronics was fun, but the chirping was booorrring. But I vaguely recall a 5/8 wavelength antenna that had a good low-angle pattern. I didn't know the height affected the pattern that much. IIRC 5/8 wavelength seems to be what the AM stations around here. Though they'd load up a barn if it worked. -- Keith |
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