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On Sun, 5 Sep 2004 11:51:57 -0500, "Richard Fry"
wrote: appears to be Hi OM, Another punt. 73's Richard Clark, KB7QHC |
"Richard Clark" wrote
"Richard Fry" wrote: You assume That is called a punt. __________ Neither of us can write that our conclusion about that spec was based on fact. Neither of us knows. RF |
"Richard Harrison" wrote in message
... Brian Reay wrote: "---dying to hear at what frequencies directional couplers suddenly begin to exist." It isn`t sudden. They sure work at audio frequencies. In telephones, they are used to prevent the user`s voice from overpowering the distant party`s voice in the user`s ear. They are called hybrids. Hybrids are also used to couple a 2-wire circuit which simultaneously carries both directions of transmission with a 4-wire circuit consisting of a transmit pair and a receive pair. Best regards, Richard Harrison, KB5WZI Thank you for that Richard but I think you missed the British sense of humour (or humor) ;-) -- Brian Reay www.g8osn.org.uk www.amateurradiotraining.org.uk FP#898 |
Richard Fry wrote:
"At least there appears to be an acknowledgement that some RF amplifiers do not have a source impedance that is the conjugate of their load impedance." Those may be anomalous. I recommend King, Mimno, and Wing to anyone desiring the complete story on the conjugate matches. To the extent that the amplifier is designed for a performance on demand that stresses it to its maximum safe dissipation, an amplifier of the Class C variety is designed for a perfectly matched load. It`s the economical thing to do. You supply the tube with about all the volts it can safely take. Then you supply it with just enough load impedance to limit its current to all it can take under the heaviest loading it well encounter. That would be when it is conjugately matched to a 50-ohm load, the usual cable impedance specification. The tank circuit is mostly a harmonic filter providing a very high impedance to the fundamental frequency and shorting out the harmonics. Best regards, Richard Harrison, KB5WZI |
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On Sun, 5 Sep 2004 12:21:21 -0500, "Richard Fry"
wrote: "Richard Clark" wrote "Richard Fry" wrote: You assume That is called a punt. __________ Neither of us can write that our conclusion about that spec was based on fact. Neither of us knows. Hi OM, This is called indicting your own authority - far more desperate than a punt. So,to this point you have failed to offer a technical discussion (Xeroxed work of others accomplishments offered in its place is rather banal), no personal experience at the bench to support your thesis, you condemn your own authority, and you complain of my attitude. Of those, perhaps the last is accurate as I find your responses to my technical comments (supported by others you claimed would not rise to a common camp) are met with risible content. Even in the comedic foray you are seriously mismatched. 73's Richard Clark, KB7QHC |
Richard Fry wrote:
"I also vaguely note some inference of peduliar intermodulation products that would be produced by a transmitter with 50 Ohm output characteristics---" First transmitting plant I worked in back in 1949 was that of KPRC / KXYZ. These each used an RCA 5-C. Transmitters were 250-watt exciters driving 5 KW water cooled linear final amplifiers. The interesting thing about this plant was that the 950 KHz and 1320 KHz transmitters both fed a common main antenna. Each station had its own directional tower on the side. The way to avoid intermodulation is to keep the foreign signals out of the electronics so they don`t mix. Well designed and adjusted pass/reject fikters in the transmission circuits of KPRC and KXYZ saw to that. Best regards, Richard Harrison, KB5WZI |
"Wes Stewart" wrote in message ... On Sun, 5 Sep 2004 12:18:09 +0000 (UTC), "Reg Edwards" wrote: |What's a directional coupler? |What do they look like? |Don't bother answering those questions. | |Why do the arguers, when caught in a tight corner, always escape to UHF for |help from directional couplers? | |There are NO directional couplers at HF. They are as scarce as real swr |meters. So they cannot be used in futile attempts to explain what really |happens at HF. | |You're next move will be to drag in scattering-matrices. Why not. I have used an HP3577 network analyzer with an S-parameter test set that was specified to work over the frequency range of 100 Hz to 200 Mhz. I guess the guys at HP didn't realize that you can't do this. ================================= Wes, Why do USA citizens invariably introduce the type numbers of their favourite, indeed worshipped articles when they have not the slightest bearing on an argument. To base one's position on a lifeless piece of hardware rather than logic is surely unsafe. What on Earth is an HP3577? In the whole of my career I have never heard of the number 3577. Is it a prime? Traditionally, in the UK, the letters HP on the side of a savoury sauce bottle stand for "Houses of Parliament". Unless a 3577 can unambiguously measure the swr on a non-existent transmission line I'm afraid its presence will serve only to further agravate the argument. Which I'm sure is the last thing you would want. ;o) Can it? --- Reg, G4FGQ |
"Richard Harrison" wrote
Richard Fry wrote: "I also vaguely note some inference of peduliar intermodulation products that would be produced by a transmitter with 50 Ohm output characteristics---" _________ How do find it justified to assign a literal quote to me that I did not write in the first place? RF |
"Richard Clark" wrote
authority - far more desperate than a punt. ...So,to this point you have failed to offer ... personal experience at the bench to support your thesis... Incorrect. See my post earlier today about reflection measurements I made of TV transmit antenna systems. That's better than the bench. It's real life. The thesis has been proven. Even in the comedic foray you are seriously mismatched. An arena in which I don't (and don't wish to) compete, however. RF |
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