From: =?iso-8859-1?Q?VIGILANT_Luis_Fern=E1ndez?= <luis@vigilant.es>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Thread-Topic: LF: 23:16    136 G6AVK de EB3FRN-1 Op32 Deep Search 725 mi -40
 dB
Thread-Index: AQHQkjMNiOUTj9URcEuC3UbROTSh+52DURkAgAArD7A=
Date: Tue, 19 May 2015 17:03:44 +0000
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Subject: RE: LF: 23:16    136 G6AVK de EB3FRN-1 Op32 Deep Search 725 mi -40
 dB
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Hi Jan, Stefan

I have been using the vertical antenna (11m really) as a first Tx Ae, with NO loading coil
and 11m wire hanging down as counter poise. A 7Mhz vertical dipole suspended at 90m high really

The horizontal loop is 10dB over the vertical on my monitor at 7Km. But would be interesting
to test the vertical with a coil and proper adapter. I guess can try this quicker than the slopper

The building structure is made of metal reinforced concrete. Probably the choice to get a counter poise
is the fire extinguish wet column, which runs inside the building. A true metal pipe filled with water and not connected 
to houses, just to hoses for emergency use. I can also run a wire down parallel to this pipe but not sure
if can connect it to true ground at the bottom

Which feeding system and coil do you suggest ?

Perfectly understood the path stability problems on MF Stefan. At the moment I keep QRSS on 476.177
and got reports from EA1FAQ, EA4NZ and EB3FRN. I have set a kinf of "contest" sending different messages
that they have to copy. This are some winner screenshots. Tx time for DFCW is 60 sec. Will try shorter

https://dl.dropboxusercontent.com/u/7162072/Docs/EA1FAQ%20Rx%20QRSS%20MF%2015%20mayo%202015.jpg

https://dl.dropboxusercontent.com/u/7162072/Docs/EB3FRN%20copy%20EA5DOM%20QRSS%20476KHz.bmp

https://dl.dropboxusercontent.com/u/7162072/Docs/EA4NZ%20Rx%20QRSS%20MF.jpg

LF/MF
Always learning ! Always fun :-)

73 de Luis
EA5DOM
 

-----Mensaje original-----
De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de pa3abk
Enviado el: martes, 19 de mayo de 2015 17:50
Para: rsgb_lf_group@blacksheep.org
Asunto: Re: LF: 23:16 136 G6AVK de EB3FRN-1 Op32 Deep Search 725 mi -40 dB

If his building has a "metal frame" and he is able to get a firm hardware connection to that, it is worth to try.
In the maritime world, e.g. drill rigs, the antenna tuner for the heli beacon is sometimes found in top of the drill tower with a small "attic" 
as counter poise.

The whole drill tower becomes part of the antenna.
The improved height benefits the radiation.
BTW it's very rare that in a oil hazardous enviroment these kind of antenna's are accepted.

See attachment of antenna of a drill rig Pelican.
In this link you can see the attic on top the tower:
http://www.gustomsc.com/index.php/zoo/reference-list/doc_download/596-pelican-class-drillships

Jan/pa3abk


On 19-5-2015 14:50, DK7FC wrote:
> Hi Luis,
>
> Am 19.05.2015 12:46, schrieb VIGILANT Luis Fernández:
>> [...]
>> It is amazing to check how just a little of vertical antenna height 
>> increase can boost the Tx signal ! :-)

> ...so maybe it is worth to try a 10m vertical on your high rise 
> building? :-)

>
>> The question is .... What should be expected from a Op2H with Dynamic 
>> Search ??
> For low distances it will work as expected, i.e. about 120/30 = 4 => 6 
> dB 'better' but for DX you will need a stable path! This will work on 
> VLF but not on LF and not at all on MF.  This is why WSPR-15 is used 
> on LF but not on MF.
> For MF, something arround QRSS-10 is the slowest useful mode i think, 
> at least for DX. See 
> https://dl.dropboxusercontent.com/u/19882028/MF/DK7FC_QRSS-10_476_KHz_
> 12-28-2012.jpg to get an impression how blurry a QRSS-10 MF signal 
> becomes in some 1000 km distance.
>
> 73, Stefan
>
>

--
pa3abk <-> dordrecht jo21it
Sent by Philips STB-75 with T100