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#11
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Richard Clark wrote:
On Wed, 23 Feb 2005 19:08:20 GMT, gwhite wrote: RF transmitters are not .... Sorry OM, This was all nonsense. Nice articulation. I don't know who OM is, but RF transmitter power amps are not "impedance matched." Neither are audio power amps for that matter. |
#12
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In article , gwhite wrote:
Richard Clark wrote: On Wed, 23 Feb 2005 19:08:20 GMT, gwhite wrote: RF transmitters are not .... Sorry OM, This was all nonsense. Nice articulation. I don't know who OM is, but RF transmitter power amps are not "impedance matched." Neither are audio power amps for that matter. "OM" is an amateur radio term. It is short for "Old Man". It is a respectful term for all other males that is quick to transmit via Morse code. Richard Clark appears to be an amateur radio operator or the like. RF transmitter power amps are certainly "impedance matched" to the intended load. Take a look in the ARRL "The radio amateur's handbook". If you have the 1944 addition, you will need to start reading at page 96 in the lower right column. If you don't have that, try Motorola's AN-721. As for audio amp, you are 1 for 3 my friend. -- -- forging knowledge |
#13
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On Fri, 25 Feb 2005 03:17:12 GMT, gwhite wrote:
RF transmitter power amps are not "impedance matched." Neither are audio power amps for that matter. Hi OM, You seem to be shy of facts and long on claims. Got any experience at the bench, or is this all arm-chair philosophy? 73's Richard Clark, KB7QHC |
#14
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Dear gwhite [no call, no location]:
Notwithstanding the clear limitations on making conclusions about what happens inside of a circuit that has been modeled using Thevenin's theorem, it is part of Religion that the least important theorem in circuit theory is applicable. Debates about Faith are a waste of energy. Avoid the tar-baby. 73 Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: "gwhite" |
#15
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Ken Smith wrote:
RF transmitter power amps are certainly "impedance matched" to the intended load. Take a look in the ARRL "The radio amateur's handbook". If you have the 1944 addition, you will need to start reading at page 96 in the lower right column. If you don't have that, try Motorola's AN-721. A CMOS Class-E amp is in full saturation (0.5v at 2a) for 10% of a cycle and off (12v at 0a) for the other 90% of a cycle. The tank circuit changes the digital energy to analog energy by filtering out everything except the fundamental frequency component. How in the world does one determine the steady-state impedance of the CMOS source? Isn't the best one can do with a digital switch is to keep it within specified parameters? The CMOS device dissipates 2 watts for 10% of the time - therefore 0.2 watts steady-state. -- 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 =--- |
#16
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Cecil Moore wrote:
The CMOS device dissipates 2 watts for 10% of the time - therefore 0.2 watts steady-state. Sorry, should have been: The CMOS device dissipates one watt for 10% of the time - therefore 0.1 watts. ----== 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 =--- |
#17
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Ken Smith wrote:
RF transmitter power amps are certainly "impedance matched" to the intended load. Take a look in the ARRL "The radio amateur's handbook". If you have the 1944 addition, you will need to start reading at page 96 in the lower right column. If you don't have that, try Motorola's AN-721. It appears that I may have canceled an earlier posting by accident so will repeat it. A certain Class-E CMOS amp is in full saturation for 10% of a cycle, 0.5v at 2a. For the rest of the time it is off. The supply voltage is 12v. What is the steady-state impedance of the source at the fundamental frequency? -- 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 =--- |
#18
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On Fri, 25 Feb 2005 09:47:16 -0600, Cecil Moore
wrote: Ken Smith wrote: RF transmitter power amps are certainly "impedance matched" to the intended load. Take a look in the ARRL "The radio amateur's handbook". If you have the 1944 addition, you will need to start reading at page 96 in the lower right column. If you don't have that, try Motorola's AN-721. It appears that I may have canceled an earlier posting by accident so will repeat it. A certain Class-E CMOS amp is in full saturation for 10% of a cycle, 0.5v at 2a. For the rest of the time it is off. The supply voltage is 12v. What is the steady-state impedance of the source at the fundamental frequency? Now, now, Cecil! Don't sully the thread with facts !-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice480)460-2350 | | | E-mail Address at Website Fax480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#19
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"gwhite" wrote in message ... Richard Clark wrote: On Wed, 23 Feb 2005 19:08:20 GMT, gwhite wrote: RF transmitters are not .... Sorry OM, This was all nonsense. Nice articulation. I don't know who OM is, but RF transmitter power amps are not "impedance matched." Neither are audio power amps for that matter. My stereo amp has a spec on output impedance. As I recall, it was around 0.16 Ohms. Intended load is 4 - 16 Ohms. Tam |
#20
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Ken Smith wrote:
RF transmitter power amps are certainly "impedance matched" to the intended load. 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. If you want to study RF PA's I suppose Cripps is one of the best I know of for a modern text: http://www.amazon.com/exec/obidos/tg.../-/0890069891/ |
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