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#12
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On 4 Jan 2005 20:58:31 -0800, "
wrote: Howard-- Thanks for the info--I'll do some reading up on both the of those options. One thing is puzzling me, though: the DX-160 has no coax input--only "screw-type" terminals. So I'm guessing that some other adapter is needed in addition to the transformer? Thanks for the help...! SWS SWS, It's been about 30 years since I owned my DX-150A and I had forgotten about the antenna connection scheme. Will rethink this while I read the other responses. Howard |
#13
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On Wed, 05 Jan 2005 12:23:44 GMT, "Merwin Dooley"
wrote: Try this. http://www.grove-ent.com/WR0130.html I lokked at that and am amazed that a balun can give 5dB gain! What I would expect is that it could help in reducing the noise floor and thus sound like you have gain; or provide a better impedence match (at some frequency(ies) to allow more signal to pass - perhaps. But gain, nope - I just don't see it unless I have totally missed out on some part of my radio education. Howard 1) The DX-160 has an Antenna trim knob, so is a preselctor redundant? 2) The 9:1 matching impedance transformer is intriguing, but can they be found/purchased already built? Thanks in advance for any input! SWS |
#14
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#15
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Howard wrote: On Wed, 05 Jan 2005 12:23:44 GMT, "Merwin Dooley" wrote: Try this. http://www.grove-ent.com/WR0130.html I lokked at that and am amazed that a balun can give 5dB gain! What I would expect is that it could help in reducing the noise floor and thus sound like you have gain; or provide a better impedence match (at some frequency(ies) to allow more signal to pass - perhaps. But gain, nope - I just don't see it unless I have totally missed out on some part of my radio education. Howard You've missed a lot... It ain't rocket science... Damn. dxAce Michigan USA 1) The DX-160 has an Antenna trim knob, so is a preselctor redundant? 2) The 9:1 matching impedance transformer is intriguing, but can they be found/purchased already built? Thanks in advance for any input! SWS |
#16
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On Wed, 05 Jan 2005 23:31:40 -0500, dxAce wrote:
Howard wrote: On Wed, 05 Jan 2005 12:23:44 GMT, "Merwin Dooley" wrote: Try this. http://www.grove-ent.com/WR0130.html I lokked at that and am amazed that a balun can give 5dB gain! What I would expect is that it could help in reducing the noise floor and thus sound like you have gain; or provide a better impedence match (at some frequency(ies) to allow more signal to pass - perhaps. But gain, nope - I just don't see it unless I have totally missed out on some part of my radio education. Howard You've missed a lot... It ain't rocket science... Damn. dxAce Michigan USA Huh? If I'm mistaken, which could be, at least give me a hint why I'm wrong and I will follow up on it. I know this isn't rocket science as I work with rocket scientists and many know little about radio. Until shown otherwise I stand by my statement that the balun will not add gain to the antenna - though it has other characteristics that will improve the received signal. Have a good one DX, Howard ps - I don't use a portable as my primary receiver 8-} |
#17
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Howard wrote:
Huh? If I'm mistaken, which could be, at least give me a hint why I'm wrong and I will follow up on it. Oh, ignore our professional idiot. You did miss something, however. The impedence mismatch makes the energy transfer from the antenna to the receiver to be inefficient. 5 dB is just about right for any 9:1 matching transformer (from an end-fed wire to a 50 ohm load). I'm not going to attempt to explain the theory behind it since I will certainly leave something out and the peanut gallery will come to life again, but think about SWR and reflected power and how bad the mismatch can be without the transformer vs. how bad it would be with the transformer. For a practiacal demonstration try (BRIEFLY) to feed a speaker from a tube amp without using a matching transformer. (You'll want a blocking capacitor, though.) I know this isn't rocket science as I work with rocket scientists and many know little about radio. :-) Until shown otherwise I stand by my statement that the balun will not add gain to the antenna - though it has other characteristics that will improve the received signal. No, no *gain* added to the antenna, but better power transfer to the radio from the antenna. 5 dB is what I've measured as well. I use ICE prepackaged transformers and Mini-Circuits transformers. Have a good one DX, Howard ps - I don't use a portable as my primary receiver 8-} -- Eric F. Richards "Nature abhors a vacuum tube." -- Myron Glass, often attributed to J. R. Pierce, Bell Labs, c. 1940 |
#18
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"Eric F. Richards" wrote: Howard wrote: Huh? If I'm mistaken, which could be, at least give me a hint why I'm wrong and I will follow up on it. Oh, ignore our professional idiot. You did miss something, however. The impedence mismatch makes the energy transfer from the antenna to the receiver to be inefficient. 5 dB is just about right for any 9:1 matching transformer (from an end-fed wire to a 50 ohm load). I'm not going to attempt to explain the theory behind it since I will certainly leave something out and the peanut gallery will come to life again, but think about SWR and reflected power and how bad the mismatch can be without the transformer vs. how bad it would be with the transformer. For a practiacal demonstration try (BRIEFLY) to feed a speaker from a tube amp without using a matching transformer. (You'll want a blocking capacitor, though.) I know this isn't rocket science as I work with rocket scientists and many know little about radio. :-) Until shown otherwise I stand by my statement that the balun will not add gain to the antenna - though it has other characteristics that will improve the received signal. No, no *gain* added to the antenna, but better power transfer to the radio from the antenna. 5 dB is what I've measured as well. I use ICE prepackaged transformers and Mini-Circuits transformers. OK, so it adds 'system' gain. Call it what you want! dxAce Michigan USA |
#19
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"Eric F. Richards" wrote: Howard wrote: Huh? If I'm mistaken, which could be, at least give me a hint why I'm wrong and I will follow up on it. Oh, ignore our professional idiot. If I'm a 'professional idiot' then I'm a damn good one! LOL dxAce Michigan USA |
#20
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wrote:
1) The DX-160 has an Antenna trim knob, so is a preselctor redundant? 2) The 9:1 matching impedance transformer is intriguing, but can they be found/purchased already built? Some food for thought... http://web.telia.com/~u85920178/ Which has this in it. It's hard to find, but it's there. http://web.telia.com/~u85920178/antennas/balun0.htm mike |
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