Fw: Fw: Re: [Antennas] 450 Ohm Ladder Line
Joe Giacobello, K2XX
[email protected]
Thu, 12 Dec 2002 15:48:30 -0500
Well, roughly speaking, your 100 watts is more like 25 watts and your
600 watts is more like 150 watts with 6 dB loss. Six dB is the typical
gain one gets with a three element tribander, obviously not small change.
73, Joe
E. Jerold Forwood wrote:
>Excuse me! I forgot! How many db's does it take to equal one S unit?
>In the far field?
>How much less is the guy on the other end apt to hear me when I am
>running my linear at 600 Watts v/s barefoot at 100 Watts?
>73's de Jerry, K�EJF
>
>On Thu, 12 Dec 2002 13:25:37 -0500 "Joe Giacobello, K2XX" <[email protected]>
>writes:
>
>
>>I happened to save a copy of some test measurements that Tom, W8JI,
>>made
>>with 450 ohm ladder line back a few years ago. The experimental
>>data
>>show that there is substantial loss when burying the line in PVC
>>pipe.
>> His report is pasted below.
>>
>>73, Joe
>>
>>You will be amazed at the attenuation caused by the soil,
>>especially if you allow the ladderline to get near the wall of the
>>buried pipe.
>>
>>Balanced lines have a strong field extending at least a few
>>conductor spacings outside the line in a plane in-line with the flat
>>
>>part of the line, and to a lesser extent broadside to that plane
>>REGARDLESS of the fact they might have little far-field radiation.
>>
>>My original post was:
>>
>>Since no one knows what happens when open wire line is buried, I
>>measured some today. The line was heavy duty one inch spaced
>>twinline, with 14 gauge stranded conductors. The measured dry
>>impedance of a 50 foot dry sample was 328 ohms, although the
>>line is advertised as 450 ohm line.
>>
>>Digital photographs are available if anyone wants to put this on a
>>Web Site.
>>
>>50 foot 15 MHz loss measured with Wiltron Network Analyzer
>>(matched line conditions in every case):
>>
>>Dry line suspended in air= .12 dB
>>
>>Dry line laid on 3 inch tall dry grass, held up off the dirt unknown
>>
>>amount by the fairly thick grass= .83 dB
>>
>>Dry line pulled in 2" PVC white plumbing pipe laying on grass =
>>1.55 dB
>>
>>Dry line buried 3-6 inches deep in PVC pipe in fairly dry dirt =
>>4.12
>>dB
>>
>>Same dry line in same pipe with dirt soaked with hose = 6.81 dB
>>
>>Same dry line back in air = .15 dB
>>
>>Line being wet down with heavy mist = .63 dB
>>
>>Line slightly wet but not being misted for several minutes = .28 dB
>>
>>Line was rematched to eliminate mismatch loss as impedance
>>changed, and matching network loss zeroed-out with analyzer.
>>
>>
>>73, Tom W8JI
>>[email protected]
>>
>>
>>
>>Dan Richardson wrote:
>>
>>
>>
>>>At 12:35 PM 12/11/2002 -0600, you wrote:
>>>
>>>
>>>
>>>>On the other hand...........
>>>>
>>>>* Ladder line tests were performed at 50MHz to 150Mhz
>>>>
>>>>
>>(instrumentation
>>
>>
>>>> limitation) where losses are greater .....not at HF, 160m -
>>>>
>>>>
>>10m
>>
>>
>>>Knowing those values it is easy to calculate the losses at lower
>>>frequencies. The formula is given in the article.
>>>
>>>
>>>
>>>>* Many of the tests were performed with Wireman Type 554
>>>>
>>>>
>>....should
>>
>>
>>>> also use the larger AWG.
>>>>
>>>>
>>>Not so. He measured Wireman's numbers 551, 552, 553 & 554 the
>>>
>>>
>>results
>>
>>
>>>are shown in Table 1.
>>>
>>>
>>>
>>>>* The premise is that you are trying to load random length
>>>>
>>>>
>>dipoles
>>
>>
>>>>due to
>>>> space limitations .....the antennas I feed are "tuned
>>>>
>>>>
>>dipoles".
>>
>>
>>>I believe he was cautioning that substantial losses can and will
>>>
>>>
>>take
>>
>>
>>>place feeding short (less 3/8-wavelength) dipoles with window
>>>
>>>
>>line.
>>
>>
>>>>* Wet measurements are made by wetting the line, including an
>>>>
>>>>
>>open wire
>>
>>
>>>> "reference line" which had NO change (indicates that a high
>>>>
>>>>
>>moisture
>>
>>
>>>> "mist" dielectric was not considered) .....this also implies
>>>>
>>>>
>>that the
>>
>>
>>>>change
>>>> in impedance and attenuation shown is due to a wet ladder web
>>>>
>>>>
>>only.
>>
>>
>>>> Making the web smaller should help this.
>>>>
>>>>
>>>Mist? Really? And how are you going to qualify that one and make
>>>
>>>
>>it
>>
>>
>>>repeatable?
>>>
>>>Both wet and dry measurement are shown. (Again Table 1)
>>>
>>>
>>>
>>>
>>>>I'd also like to know, for a HF antenna system, do you get more
>>>>
>>>>
>>power
>>
>>
>>>>radiated by the resonant antenna if 1) you have an impedance
>>>>
>>>>
>>mismatch
>>
>>
>>>>of 9:1 (with it's resultant SWR) between 200ft of 450ohm
>>>>
>>>>
>>transmission
>>
>>
>>>>line and the 50ohm antenna .....or 2) if you use a toroidial 9:1
>>>>transformer
>>>>(with it's loss) between the balanced transmission line and the
>>>>
>>>>
>>balanced
>>
>>
>>>>antenna ?
>>>>
>>>>
>>>>
>>>The article addresses the window line losses only. For comparisons
>>>
>>>
>>>with other systems you're going to have to dig deeper elsewhere.
>>>
>>>Danny
>>>
>>>
>>>
>>>
>>>>Fun stuff.
>>>>
>>>>73 Kees K5BCQ
>>>>
>>>>--------- Forwarded message ----------
>>>>From: Sandy and Kees Talen <[email protected]>
>>>>To: [email protected]
>>>>Date: Wed, 11 Dec 2002 11:06:33 -0600
>>>>Subject: Fw: Re: [Antennas] 450 Ohm Ladder Line
>>>>
>>>>Great article, thanks Dan. It's always good to see real data,
>>>>
>>>>
>>determined
>>
>>
>>>>using a controlled experiment, and excellent test equipment.
>>>>
>>>>73 Kees K5BCQ
>>>>
>>>>
>>>>------- Forwarded message ----------
>>>>From: Dan Richardson <[email protected]>
>>>>To: [email protected]
>>>>Date: Wed, 11 Dec 2002 08:24:01 -0800
>>>>Subject: Re: [Antennas] 450 Ohm Ladder Line
>>>>Message-ID:
>>>>
>>>>
>><[email protected]>
>>
>>
>>>>For those interested here is URL which provides a very through
>>>>
>>>>
>>analysis
>>
>>
>>>>on
>>>>this subject.
>>>>
>>>>http://users.triconet.org/wesandlinda/ladder_line.pdf
>>>>
>>>>Danny, K6MHE
>>>>
>>>>
>>>>No trees were destroyed in the sending of this message.
>>>>However, a large number of electrons were terribly
>>>>
>>>>
>>inconvenienced.
>>
>>
>>>>- - -
>>>>
>>>>Your moderator for this list is:
>>>>Larry Wilson KE1HZ [email protected]
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>>>>
>>>>Your moderator for this list is:
>>>>Larry Wilson KE1HZ [email protected]
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>>>>Antennas mailing list
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>>>>
>>>>
>>>Danny
>>>K6MHE
>>>
>>>No trees were destroyed in the sending of this message.
>>>However, a large number of electrons were terribly
>>>
>>>
>>inconvenienced.
>>
>>
>>>- - -
>>>Your moderator for this list is:
>>>Larry Wilson KE1HZ [email protected]
>>>_______________________________________________
>>>Antennas mailing list
>>>[email protected]
>>>http://mailman.qth.net/mailman/listinfo/antennas
>>>
>>>
>>>
>>>
>>- - -
>>
>>Your moderator for this list is:
>>Larry Wilson KE1HZ [email protected]
>>_______________________________________________
>>Antennas mailing list
>>[email protected]
>>http://mailman.qth.net/mailman/listinfo/antennas
>>
>>
>>
>>
>
>
>E. Jerold (Jerry) Forwood
>
>
>
>