Re: [loopantennas] RE: Question About Tuned Magnetic Loop
- Bob VE3UK, It's late afternoon here, in Canada you'll be asleep, makes communication a little difficult. In your last? Email "No, the feed point...." you reacted negatively to a statement, what was that statement mon ami? In anticipation Max vk2tti.
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On 23/09/2013, at 4:11, <leschyna@...> wrote:
No, the feed point should be very close to 50 ohms that is what the transformer is doing. However, a 1:1 balun does have its place in further limiting the noise picked up by the loop and sent to your RX via common mode.
Hope that helps.
73 Bob VE3UK
--- In firstname.lastname@example.org, <vk2tti@...> wrote:Tony and all, I am troubled by the repeated reference to the word balun, unless I have read incorrectly, nowhere does G0CWT refer to his transformer feed as a balun! And rightly so, whether or no it affects the balance of the loop I have no way of measuring. In practice it would not matter much, if I can't hear the difference does it matter? Regards to all, Max vk2tti.
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On 22/09/2013, at 13:20, Tony Magon <temagon@...> wrote:Tony VK2ICHi Max and allI have made one up for 40 meters and tried it out briefly and it worked quite well. The balun tubes can be purchased from Jaycar.
73On Sun, Sep 22, 2013 at 11:55 AM, <vk2tti@...> wrote:
G'day Tony and all. Thank you for the heads up re G0CWT website have gone straight to it. Very impressive video with the neon tube and the high voltage and the clamp on current measure. My youngest daughter joined the human race and went to uni studdied engineering as a mature age student, now she am be one wiff a first and second class honours to her credit. She came homn one day said " You know Dad when you try to measure something you change it! ". It seems to me that G0CWT has demonstrated that adding an unbalanced pickup loop to a tuned loop alters the theoretical current and voltage distribution expected. I would like to see the same demonstration done without the pickup loop. The problem then becomes how to excite the loop in free space! Still an interesting website. Max VK2TTI.
Sun, 22 Sep 2013 09:48:19 +1000
----- Original Message -----To:<email@example.com>Cc:Sent:Subject:Re: [loopantennas] Question About Tuned Magnetic Loop
Tony VK2ICHi MaxHave a look at G0CWT website.
73On Sun, Sep 22, 2013 at 9:44 AM, Maxwell Mclellan <vk2tti@...> wrote:
G'day all again. Some more thoughts re main loop/pickup loop thing. If you consider them as a transformer a multi turn (say 10 turns) and a pickup loop (1 turn).Voltage (in the secondary) is reduced by 10 and the current available increased by 10 ( to keep P=RI). Impedance transformation is to the square of the turns ratio, assuming a 50 ohm secondary the the primary winding will be 50 x 100= 5000 ohms. A parallel tuned loop exhibits a high impedance. If you assume a 100ohm secondary we get a transformation of a 100 x100= 10,000 ohms ( I hope my Maths is right. If we consider a 1 turn loop and pickup the square of 1 is 1 ie no impedance transformation. That is why I gave away pickup loops for single turn loops. Copper pipe is good but expensive, for small loops I prefer aluminum strip, gets an oxide film but can be brushed clean with a brass wire brush. I believe ( religion ) that an unbalanced pickup will unbalance the system. Regards again, Max VK2TTI.
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