From: "Clemens Paul" <cpaul@gmx.net>
To: <rsgb_lf_group@blacksheep.org>
References: <94719482.20170623130346@gmail.com> <EFA843B116824E4B89B87C3BAAE2DB33@Clemens0811> <408186507.20170624173207@gmail.com> <1B7B7537AD024FBDAA5E898E3DF21AAB@Clemens0811> <1483178977.20170624190258@gmail.com> <A1807AACE4FF4AA38C1FB06188042EB7@Clemens0811> <741897120.20170624204412@gmail.com> <2A1ED0432B3E4914AF1896E8F1B83924@Clemens0811> <498643488.20170626115655@gmail.com>
In-Reply-To: <498643488.20170626115655@gmail.com>
Date: Tue, 27 Jun 2017 20:38:13 +0200
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Subject: RE: LF: RE: Transformer questions.
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Hi Chris,

>I seem to be being
>told  the  impedance  matching  transformer  in the white box could be
>upstairs  in the shack by one, and it has to be by the loading coil by
>your good self! 

In my first reply from 24.6.2017
"This would be possible but more or less lossy"
it was not clear to me that you would possibly like to tap the transformer
*of the combiner* and that the LPF is ahead of it.
So,as I said in my last reply it is the best to let things as they are.

73
Clemens
DL4RAJ 


>-----Original Message-----
>From: owner-rsgb_lf_group@blacksheep.org 
>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Chris Wilson
>Sent: Monday, June 26, 2017 12:57 PM
>To: Clemens Paul
>Subject: Re: LF: RE: Transformer questions.
>
>Hello Clemens,
>
>
>Thanks   for   the   reply,   I  have  posted  a  link  to  photos  at
>http://www.gatesgarth.com/radio.zip   that  show  the  outside  stuff.
>Perhaps  that  will  make the set up a bit clearer. I seem to be being
>told  the  impedance  matching  transformer  in the white box could be
>upstairs  in the shack by one, and it has to be by the loading coil by
>your good self! Reading what you have said below, I think it should be
>where  it  is, but hopefully the photos and explanation in my reply to
>the  insulated mast thread will confirm. Photos speak a thousand words
>:)
>
>Sunday, June 25, 2017, 1:19:54 PM, you wrote:
>
>> Hi Chris,
>
>> ok, I hope I have now understood your set up and what you 
>may possibly want to change.
>> Present configuration:
>
>>>2  X  amps to combiner via 2 off 12 inches Teflon coax 
>cables : Combiner
>>>to  LPF via 12 inches Teflon co-ax : Combiner to outside 
>about 40 feet
>>>RG-213  co-ax  :  Outside  is impedance matching transformer 
>on top of
>>>loading  coil / variometer : Impedance matching transformer 
>to loading
>>>coil  via  12  inches  RG-213 : Loading coil feeds vertical 
>section of
>>>antenna directly. 
>
>> And from an earlier post by you:
>
>>>>Can I wind the isolating
>>>>transformer as a 1 : 1 and do impedance matching (which changes with
>>>>weather / foliage growth) indoors using a tapped combiner auto
>>>>transformer? 
>
>> So you want to modify the combiner-autotransformer into a tapped one
>> and OTOH modify the tapped isolation transformer into a 
>non-tapped 1:1 one.(?)
>
>> This would be not a good idea.
>> The combiner XFM would not work any more,the LPF would not 
>work any more properly.
>> Both need to see 50 Ohm.
>> Even if you cancel out the antenna/feeder reactance by the loading
>> coil/variometer you are left with a
>> very low real part of impedance of a few Ohm.
>> So beside the malfunction of the combiner and the LPF you would get
>> a loss of about 2dB on the 40 feet
>> coax (assuming 2 Ohm for the real part).
>
>> 73
>> Clemens
>> DL4RAJ 
>
>
>
>
>
>
>
>-- 
>Best regards,
> Chris                            mailto:dead.fets@gmail.com
>
>
>
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