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Not to start an arguement just some thin s Ive learned over time.

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  #33  
Old 02-20-2012, 05:04 PM
Crotchety Old Bastard
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The antenna input impedance plus the impedance of the matching section for that antenna are approximately 100 ohms impedance. Parallel two of those antennas and the resulting impedance is approximately the desired 50 ohms impedance. That '100 ohms' and the resulting '50 ohms' are -only- approximations. There can be quite a variation in those impedances.
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  #34  
Old 02-20-2012, 08:31 PM
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Fine, 98 ohms, 106.371 ohms, I don't really care if it's exact, I just don't understand how 4 watts can be divided by 2 but remain 4 watts into both parallel loads, now equaling 8 watts?

If that's the case, then let's set up 128 pairs and keep piggy-back-splitting them by using 75ohm coax phasing harnesses and then the original 4 watts will now provide over 1 kilowatt?

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Old 02-20-2012, 09:03 PM
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I'd rather have a 1/4 wave vertical at 10,000 ft than a 10 element yagi at 10 ft.
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  #36  
Old 02-20-2012, 09:25 PM
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if you're using coax for the feed line on both the 1/4 and the yagi id rather have the beam at 10 ft. .
80 db of loss from 2 miles of RG8 LOL
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Old 02-20-2012, 10:01 PM
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Having just checked the price of tea in China, I've decided I'd rather have a bottle in front of me than a frontal lobotomy.
I hear the skiing is excellent this time of year.
Can you even imagine a supercharged V-8 mid-engine?
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  #38  
Old 02-20-2012, 10:17 PM
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Below I hooked two 1/2 wave 50 ohm jumpers to two 50 ohm dummy loads. I connected the jumpers to a T-connector and hooked my Autek VA1 to the third port on the T and I saw 28 ohms.

I hooked one jumper direct to the VA1 and got 49 ohms, the other image is also 49 ohms with the VA1 direct into the dummy load.

I don't have a 75 ohm co-phase harness, but if I did and hooked it up in this setup then I would expect the TX'r end of the T-connector to show close to 50 ohms. Am I wrong?

The following is not a transformational harness so we should not see any transformation by the harness, but we do see an approximate halving of the impedance at the transmitter end of the harness.

50 ohm co-phase setup into two 50 ohm dummy loads.
Co-Phase harness (640x480).jpg

VA1 into T-connector at the end of the harness.
VA1 Z value on Co-Phase (640x480).jpg

VA1 direct into a 50 ohm non-reactive dummy load.
VA1 direct to dummy load (640x480).jpg

VA1 direct into one of the jumpers and a dummy load.
VA1 thru one line into dummy load (640x480).jpg

Sorry for the meter response no showing up well, this meter is old and worn somewhat.

If I'm not wrong, then where are ya'll getting 100 ohms? Is the discussion about a mobile antenna or some other antenna like a quad or maybe a 5/8 wave with an end impedance somewhere around a 100 ohms with a lot of reactance to boot?

NB, you're getting all incredulous again, like I called your momma a bad name. I asked a civil question, and it was not a trick question about the accuracy of the impedance.

BTW, I agree with you not seeing how 4 watts....however you said it.
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Last edited by Marconi; 02-20-2012 at 10:29 PM.

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  #39  
Old 02-20-2012, 10:29 PM
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Quote:
Originally Posted by Marconi View Post
Below I hooked two 1/2 wave 50 ohm jump

NB, you're getting all incredulous again, like I called your momma a bad name. I asked a civil question, and it was not a trick question about the accuracy of the impedance.
Hi Marconi,

You turkey!

Sometimes you take things personally that are never meant that way, not by me anyway. You're the most enthusiastic user on this forum and the only one who addressed my question on topic.

...but stop calling my momma bad names!

OK, the 100 ohms is what you should get at the other end of a 75ohm electrical 1/4 wave matching transformer coming from a 50ohm load. (Don't even begin to try to make me think you don't already know this)

Two of them, each from a 50ohm antenna into a T connector should show right about 50 ohms at the single input, like your test, except double the impedance back to 50ohms.

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  #40  
Old 02-20-2012, 10:42 PM
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Quote:
Originally Posted by BOOTY MONSTER View Post
if you're using coax for the feed line on both the 1/4 and the yagi id rather have the beam at 10 ft. .
80 db of loss from 2 miles of RG8 LOL
Boy it don't take much to get you boys all bent out of shape! ^can not stand it^

Booty is right, if old 888 could get it up at 10000' feet his signal from his CB would probably peter out with about 200' - 300' feet up the coax. Plus if he was that high above everyone around him for about 200> miles, and could make a signal, nobody within that range would even know he was out there.
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