|
Reg Edwards wrote:
If a conjugate match matters two hoots, or is involved in the slightest way with the design of power amplifiers or any other sort of amplifier, why don't tube manufacturers state the internal resistance or impedance in tube date sheets? So I guess you just connect your tubes or transistor finals directly to the coax? I mean, since it doesn't matter... Tom K0TAR |
In article ,
Tam/WB2TT wrote: [...] When device people talk about "matching", they mean matching the load to what the transistor wants to see, which is not the conjugate of the output impedance. Actually, in this case, I was speaking of matching the transmitter's output to the load. The transmitter already contains gawd knows what L and C components etc. The OP has a completed transmitter and a hunk of wire. If he matches the wire to what the transmitter wants to see, the transmitter will be happy. If he causes a reactive current to flow that the designer did not design for he will cause added heating in the output device. If the designer did a good job, the transmitter will protect its output devices and thus end up producing less power. Also if he makes the real component of the impedance vary from what the designer intended, the output power will decrease. Which direction gets limited by the Vcc and which by the protection circuit depends on the collection of Ls and Cs inside the transmitter. -- -- forging knowledge |
Ken Smith wrote:
Now lets assume that you slightly decrease the resistance. Since we are assuming that this is a well designed case, we can assume that the designer took steps to ensure that the output devices would be protected from excess currents. Let's assume the designer is an amateur who didn't provide any protection for his tube's output. The lower the resistive load, the more current the output device draws until it fails. What is the output impedance of the device? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Rich Grise wrote:
Evidently, the guy's never tuned up a 40 meter pi-net output transmitter. ;-) If that's not impedance matching, I don't know what it is! (Oh, "Load line" matching? What are the two parameters of the load line? Voltage and Current, right? What's the slope of the load line? Impedance!) And there's the catch. If the load line is the source impedance, the load (not the designer) effects the source impedance. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Reg Edwards wrote:
If a conjugate match matters two hoots, or is involved in the slightest way with the design of power amplifiers or any other sort of amplifier, why don't tube manufacturers state the internal resistance or impedance in tube date sheets? When I first became a ham, transmitters didn't have any protection at all. They would keep putting out more and more power until the final or power supply got too hot. My 6L6 went out during a contest in the 50's. All I had to replace it with was a metal 6V6. What's the source impedance of a 6V6 plugged into a 6L6 socket? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
The phrase "output impedance" in connection with amplifiers is ambiguous and
likely to result in arguments. The correct description is "internal impedance" or "internal resistance" and should always be used. ---- Reg. |
Ken Smith wrote:
If you then put in the output device protection they didn't include, you end up with the matching as I explained elsewhere. SWR foldback is part of impedance matching? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
"Reg Edwards" wrote in
message ... The phrase "output impedance" in connection with amplifiers is ambiguous and likely to result in arguments. I suppose the same could be said of any block that is susceptible to having some feedback put around it. Therefore the term "output impedance" should never be used at all. And of course, any term that could, or has ever been known to lead to an argument, with any uninformed person that might come along, should be eliminated from our vocabulary. Uuugh. Mmmmph. Me drag woman to cave by hair. The correct description is "internal impedance" or "internal resistance" and should always be used. Nonsense. If I wanted to speak of an impedance inside of some circuit, I might loosely speak of it as "internal", but in any useful discussion, it would be spoken of as either an output impedance or an input impedance, and, with most people I have such discussions with, there would be no need to add that some unknown additional feed- back not part of the present discussion could alter the observable impedance. I hope your post was a troll. -- --Larry Brasfield email: Above views may belong only to me. |
I read in sci.electronics.design that gwhite wrote
(in ) about '1/4 vs 1/2 wavelength antenna', on Fri, 25 Feb 2005: I'm sorry, but they are not. Nor are any power amps that I know of. Efficiency (and thus necessarily output swing) is what matters for power amps. To maximize swing requires load line matching, not impedance matching. What is a 'load line'? A straight line on an I/V graph? What does the gradient of that line represent? -- 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 |
On Fri, 25 Feb 2005 22:35:28 -0600, Cecil Moore wrote:
Rich Grise wrote: Evidently, the guy's never tuned up a 40 meter pi-net output transmitter. ;-) If that's not impedance matching, I don't know what it is! (Oh, "Load line" matching? What are the two parameters of the load line? Voltage and Current, right? What's the slope of the load line? Impedance!) And there's the catch. If the load line is the source impedance, the load (not the designer) effects the source impedance. Apparently, I'm not following the same conversation here, because I thought that the impedance matching network (in the instant example, the pi-net output of the transmitter) was what translated the load impedance to the source impedance, matching both in the process. Thanks, Rich |
On Fri, 25 Feb 2005 21:42:37 -0800, Larry Brasfield wrote:
Uuugh. Mmmmph. Me drag woman to cave by hair. Uh. Nuh. Drag _FROM_ hair. |
My "Bailey" amps (Wireless World c. 1970) have lots
of internal resistances, all soldered in neatly by hand. In your comment below, I think that you have "output" much "impudance". "Reg Edwards" wrote in message ... The phrase "output impedance" in connection with amplifiers is ambiguous and likely to result in arguments. The correct description is "internal impedance" or "internal resistance" and should always be used. |
Rich Grise wrote:
On Fri, 25 Feb 2005 22:35:28 -0600, Cecil Moore wrote: Rich Grise wrote: If that's not impedance matching, I don't know what it is! (Oh, "Load line" matching? What are the two parameters of the load line? Voltage and Current, right? What's the slope of the load line? Impedance!) And there's the catch. If the load line is the source impedance, the load (not the designer) effects the source impedance. Apparently, I'm not following the same conversation here, because I thought that the impedance matching network (in the instant example, the pi-net output of the transmitter) was what translated the load impedance to the source impedance, matching both in the process. Maybe I inferred wrong. From your "load line equals impedance" statement above, I inferred that you were implying that the load line *is* the source impedance. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Sat, 26 Feb 2005 04:53:03 +0000 (UTC), "Reg Edwards"
wrote: The phrase "output impedance" in connection with amplifiers is ambiguous and likely to result in arguments. The correct description is "internal impedance" or "internal resistance" and should always be used. S22 is fairly well defined. Allan |
On Sat, 26 Feb 2005 08:33:25 -0600, Cecil Moore wrote:
Rich Grise wrote: On Fri, 25 Feb 2005 22:35:28 -0600, Cecil Moore wrote: Rich Grise wrote: If that's not impedance matching, I don't know what it is! (Oh, "Load line" matching? What are the two parameters of the load line? Voltage and Current, right? What's the slope of the load line? Impedance!) And there's the catch. If the load line is the source impedance, the load (not the designer) effects the source impedance. Apparently, I'm not following the same conversation here, because I thought that the impedance matching network (in the instant example, the pi-net output of the transmitter) was what translated the load impedance to the source impedance, matching both in the process. Maybe I inferred wrong. From your "load line equals impedance" statement above, I inferred that you were implying that the load line *is* the source impedance. No, just trying to make the point that it does, in fact, _have_ an impedance. (even if it's running class E.) What that exact impedance is, of course, is left as an exercise for the reader. :-) And another thing - in a transmitter, the impedance matching only happens at the one frequency, which is a lot different scenario from, say, a stereo. This could be a confusion factor here. Thanks, Rich |
John Woodgate wrote:
"The problem is that people say "output impedance" when they mean "load impedance". Quite right. I`ll use "source" and "load". Current through a load depends on the voltage. Ratio of volts to amps is the impedance. A source with the same resistance and offsetting reactance to the load enjoys a Goldilocks relationship with its load. The source`s volts and amps perfectly match the demands of the load. It`s just right. There`s no surplus of either volts or amps when source and load are connected. Its a match. Only a matched source and load deliver all the power available in a source. If we have too much resistance in our load, it doesn`t take as much power as it could. If we have too little resistance in our load, too much power is lost in our source. The perfect match of equal source and load resistances, with the reactance neutralized, is the only condition permitting maximum power transfer. Somme amateurs want all the power they can get from their transmitters. Best regards, Richard Harrison, KB5WZI |
Allan Herriman wrote:
S22 is fairly well defined. What's the S22 of an IC-756PRO? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Allan Herriman wrote:
S22 is fairly well defined. What's the S22 of an IC-756PRO? With that figure, S22^2 is defined as: Power reflected from the network output divided by Power incident on the network output. Better yet, we can then calculate the reflected power dissipated by the IC-756PRO. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Rich Grise wrote:
And another thing - in a transmitter, the impedance matching only happens at the one frequency, which is a lot different scenario from, say, a stereo. This could be a confusion factor here. Therefore, the key to converting the non-linear source to an equivalent linear source lies in a Fourier analysis? Do the other-than-fundamental terms in the Fourier analysis encounter a low impedance or a high impedance? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Richard Harrison wrote:
Some amateurs want all the power they can get from their transmitters. I learned long ago that approach burns up unprotected transmitters. Nowadays, I settle for efficiency and lots of protection circuitry. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
I read in sci.electronics.design that Cecil Moore
wrote (in ) about '1/4 vs 1/2 wavelength antenna', on Sat, 26 Feb 2005: Rich Grise wrote: And another thing - in a transmitter, the impedance matching only happens at the one frequency, which is a lot different scenario from, say, a stereo. This could be a confusion factor here. Therefore, the key to converting the non-linear source to an equivalent linear source lies in a Fourier analysis? Do the other-than-fundamental terms in the Fourier analysis encounter a low impedance or a high impedance? Yes. Not facetious; the impedance matching network can be configured to minimise individual or a few harmonic emissions by adjusting its impedances at harmonic frequencies. Either high or low (or perhaps both) can minimise the emission, depending on the configuration. -- 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 |
"Cecil Moore" wrote Allan Herriman wrote: S22 is fairly well defined. What's the S22 of an IC-756PRO? ============================= Cecil, I havn't the foggiest idea what an IC-756PRO is except that it is something which comes from that excellent manufacturer Icom. But your extremely brief question is the most hillarious ever asked on this newsgroup. You are still at the best of your form. I can't stop laughing. 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. ---- Yours, Reg. |
In article , Cecil Moore wrote:
Ken Smith wrote: Now lets assume that you slightly decrease the resistance. Since we are assuming that this is a well designed case, we can assume that the designer took steps to ensure that the output devices would be protected from excess currents. Let's assume the designer is an amateur who didn't provide any protection for his tube's output. The lower the resistive load, the more current the output device draws until it fails. What is the output impedance of the device? 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. -- -- forging knowledge |
In article , Cecil Moore wrote:
Ken Smith wrote: If you then put in the output device protection they didn't include, you end up with the matching as I explained elsewhere. SWR foldback is part of impedance matching? Yes for the purposes of the OP's case it is. He is trying to use an existing transmitter design and a hunk of wire. This seems to be the part of my argument that people are missing. I suggested he use a matching network to match the wire to the transmitter's output. -- -- forging knowledge |
John Woodgate wrote:
Cecil Moore wrote: Therefore, the key to converting the non-linear source to an equivalent linear source lies in a Fourier analysis? Do the other-than-fundamental terms in the Fourier analysis encounter a low impedance or a high impedance? Yes. Not facetious; the impedance matching network can be configured to minimise individual or a few harmonic emissions by adjusting its impedances at harmonic frequencies. Either high or low (or perhaps both) can minimise the emission, depending on the configuration. Whether the harmonic impedance is high or low would affect the efficiency, no? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
"Rich Grise" bravely wrote to "All" (26 Feb 05 16:01:31)
--- on the heady topic of " 1/4 vs 1/2 wavelength antenna" RG From: Rich Grise RG Xref: aeinews rec.radio.amateur.antenna:26047 RG sci.electronics.design:194 RG On Sat, 26 Feb 2005 08:33:25 -0600, Cecil Moore wrote: Rich Grise wrote: On Fri, 25 Feb 2005 22:35:28 -0600, Cecil Moore wrote: Rich Grise wrote: If that's not impedance matching, I don't know what it is! (Oh, "Load line" matching? What are the two parameters of the load line? Voltage and Current, right? What's the slope of the load line? Impedance!) And there's the catch. If the load line is the source impedance, the load (not the designer) effects the source impedance. Apparently, I'm not following the same conversation here, because I thought that the impedance matching network (in the instant example, the pi-net output of the transmitter) was what translated the load impedance to the source impedance, matching both in the process. Maybe I inferred wrong. From your "load line equals impedance" statement above, I inferred that you were implying that the load line *is* the source impedance. RG No, just trying to make the point that it does, in fact, _have_ an RG impedance. (even if it's running class E.) What that exact impedance RG is, of course, is left as an exercise for the reader. :-) RG And another thing - in a transmitter, the impedance matching only RG happens at the one frequency, which is a lot different scenario from, RG say, a stereo. This could be a confusion factor here. RG Thanks, RG Rich There are a couple of things meant by matching. The usual notion has to do with the plate resistance of tubes. When used in a linear mode a tube has a given plate resistance. To get the most power output from a tube its plate resistance must equal the load. The available plate current curve and equivalent load then must match the supply voltage. A transformer is needed to adjust the typically low value load resistance to the much greater plate resistance. The other notion of matching has to do with using a switched voltage to synthesize the right output voltage and current to drive a given load. This type of transformation is done by using sampling over time. Another type of transformation uses a resonnant tank circuit which, like the above transformer, can adjust the load resistance to equal that of the source resistance by a choice of the proper tank network reactances. This is a single frequency only matching however. Transistor audio impedance is never matched since an extremely low source resistance is desirable for speaker damping. Musical instrument tube amplifiers are somewhat between these since the tube power must be transformed to match the high voltage supply low plate current to the high current low voltage load, but yet must present a low source resistance damping to a speaker so uses negative feedback for this. A*s*i*m*o*v .... Ok, I pulled the pin. Now what?.....Hey! Where are you all going? |
I read in sci.electronics.design that Cecil Moore
wrote (in ) about '1/4 vs 1/2 wavelength antenna', on Sat, 26 Feb 2005: Is an amp that fails at one minute with 100w FM better matched than an amp that fails at two minutes with 100w CW? If the FM is what passes for music these days, it's MUCH better IMHO. (;-) -- 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 |
I read in sci.electronics.design that Cecil Moore
wrote (in ) about '1/4 vs 1/2 wavelength antenna', on Sat, 26 Feb 2005: John Woodgate wrote: Cecil Moore wrote: Therefore, the key to converting the non-linear source to an equivalent linear source lies in a Fourier analysis? Do the other-than-fundamental terms in the Fourier analysis encounter a low impedance or a high impedance? Yes. Not facetious; the impedance matching network can be configured to minimise individual or a few harmonic emissions by adjusting its impedances at harmonic frequencies. Either high or low (or perhaps both) can minimise the emission, depending on the configuration. Whether the harmonic impedance is high or low would affect the efficiency, no? I think the question can only be answered by 'It depends..'. For example, it is 'affected' if it's changed by 1%, but is that significant? -- 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 |
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 |
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. But I vaguely recall a 5/8 wavelength antenna that had a good low-angle pattern. ...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. |
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 :-)
|
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 |
|
| All times are GMT +1. The time now is 02:07 AM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com