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Date: Sun, 19 Jan 2014 22:13:59 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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References: <stb7jj8i36ykvnjmhn2w1jb9.1387917789184@email.android.com> <35FE4D7949D24153B93AD287570B1AA6@Clemens0811> <52CDB98E.2090806@iup.uni-heidelberg.de> <07DCC8F8EED14FA7A932FF8F90ED27A6@Clemens0811> <52CDD7DE.8080807@iup.uni-heidelberg.de> <34613E4DA8F14D389A2BCF8A04DDF0DA@Clemens0811> <52D1B87C.80005@freenet.de> <E2DE4EC9105C43E0847B31050309F109@Clemens0811> <52D1C679.9070506@freenet.de> <81046BF0DF784FB18751214A2CE7347A@Clemens0811>
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Subject: Re: LF: MW Antenna [was:RE: Clemens on MF!!]
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Hello Clemens,

What did i say...
So now you need a clean earth and maybe you can use a relay while=20
transmitting. The relay switches both earths parallel and during RXing=20
you just use the clean earth.
+6 dB, so now you're getting twice the antenna current with the same powe=
r?
Can you show us the image showing your house and the antenna again? I=20
remember there was a coax of some 10m between TX and dipole feed point=20
(?). If you can install an earth system directly below the feed point,=20
then the RF current cannot cause TVI at home.

73, Stefan/DK7FC


Am 19.01.2014 16:11, schrieb Clemens Paul:
> Hi Wolf,
>
> I've tried the T-Antenna mode this weekend.
> It was excited against PE (protective earth of the house).
> Matching was surprisingly easy by a series C of around 1340pF,
> R (the real part)  happened to be 50 Ohm (in dipole mode it varies betw=
een 60 and 70 Ohm).
> The effect was dramatic in any sense.
> Ground wave signal strength went up by ~ 20dB as measured on a remote P=
erseus in
> Amberg (nr N=FCrnberg) this afternoon.
> Sky wave signal strength during last night went up by at least 6dB,mayb=
e 10dB
> (diifficult to measure because of qsb while changing the configuration)=
 in DL as well
> in OH (1900km distance) on a remote Perseus.
> Now the downside:Rx noise level went up by roughly the same amount (day=
/night)
> and funny things happened when TXing with full power.
> The TV and some lights in the living room went off and on,there was hum=
 in the telephone
> etc.
> The RX noise problem could easily be solved by switching the two antenn=
a modes
> automatically with the PTT line and a few relays.
> The EMI problem perhaps by a separate earth?
>
> 73
> Clemens
> DL4RAJ
>
>
>   =20
>> -----Original Message-----
>> From: owner-rsgb_lf_group@blacksheep.org
>> [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of wolf_dl4yhf
>> Sent: Saturday, January 11, 2014 11:32 PM
>> To: rsgb_lf_group@blacksheep.org
>> Subject: Re: LF: RE: Clemens on MF!!
>>
>> Hi Clemens,
>>
>>
>> Am 11.01.2014 22:58, schrieb Clemens Paul:
>>     =20
>>> The dipole is a horizontal 90=B0V, 8-15m high and according to
>>>       =20
>> EZNEC it has a spheroidal
>>     =20
>>> pattern with no nulls.
>>>       =20
>> Ok... that makes a difference.
>>     =20
>>> The vertical part of the feeder is only about 6m long.
>>>       =20
>> So the rainworms will be cosy and warm around the lower parts of the
>> antenna, hi..
>>     =20
>>> Tomorrow I'll check the impedance of the antenna aagainst
>>>       =20
>> ground with both feeder wires
>>     =20
>>> connected
>>> and see if I can match it to 50 Ohm,dependent on the available parts.
>>>       =20
>> That would be a good indicator for the ground conductivity.
>> At the local antenna farm, the total resistance (after
>> compensating the
>> reactive part with a series coil) went up from 26 to approx 35 ohms
>> within a few months.
>> During transmit, I simply use the PE (plus possibly the underground
>> cables) as counterpoise. During RX, the PE is disconnected from the
>> antenna's own 'ground' which consists of a few buried wires,
>> to prevent
>> QRM from the mains creeping in. Another remote RX antenna is already
>> planned, most likely it will be a small active loop or a system of
>> crossed loops.
>>
>> Cheers,
>>    Wolf.
>>
>> ( where is everyone .. now hearing only "  -...  ..  .-  "  ? )
>>
>>
>>     =20
>
>   =20