Message-ID: <5B93B005.9030803@posteo.de>
Date: Sat, 08 Sep 2018 13:18:29 +0200
From: DK7FC <selberdenken@posteo.de>
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References: <5B8FD14A.2080403@posteo.de> <14564361536176528@iva5-e9a4c5420a84.qloud-c.yandex.net> <5B904C48.9000302@posteo.de> <13745221536184440@sas1-0a6c2e2b59d7.qloud-c.yandex.net> <5B926595.4090705@posteo.de> <106526A3B629406BBA15C3AA514D9EA7@Clemens0811>
In-Reply-To: <106526A3B629406BBA15C3AA514D9EA7@Clemens0811>
Subject: Re: LF: RE: 137 kHz WSPR-2 on a 900m long ground loop, this weekend
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Genossen!

I just matched the antenna and run some WSPR-2 transmissions on 137.425 kHz.

I'm getting 260 mA antenna current at 10 W RF power. So the overall loss 
resistance should be 150 Ohm (the wire has about 30 Ohm). For resonating 
i need about 2.5 nF in series to the wire.
So the feed point impedance is Z = 150 Ohm + j450 Ohm, still behaving as 
a loop. Quite a comfortable managable impedance. I had to wind an output 
transformer on a "RIK20" core (Reichelt!), which works very well. The 
secondary number of turns was unknown at the beginning ;-)

Regular transmissions will start in an hour or so.

73, Stefan

Am 08.09.2018 12:07, schrieb Clemens Paul:
> Hi Genosse Stefan,
>
>    
>> Will someone catch the signal at all? At least i'm already
>> asking for RX
>> stations!
>>      
> I've just resonated my antenna aa inverted L on 137.5kHz (with 502µH)
> and wil be ready to receive in WSPR-2 as soon as you start.
>
> 73
> Clemens
> DL4RAJ
>
>
>
>    
>> -----Original Message-----
>> From: owner-rsgb_lf_group@blacksheep.org
>> [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of DK7FC
>> Sent: Friday, September 7, 2018 1:49 PM
>> To: rsgb_lf_group@blacksheep.org
>> Subject: LF: 137 kHz WSPR-2 on a 900m long ground loop, this weekend
>>
>> Genosse Roman, LF,
>>
>> Yesterday i built a small LF PA providing 10 W at 50 Ohm. It
>> consumes 1
>> A at 12 VDC. I intend to run an over-night WSPR-2 transmission (20% TX
>> rate) on saturday night, using the ground loop or earth antenna in
>> JN39WI. The signal generator is a Raspberry Pi running on a separate 7
>> Ah lead gel accu. The PA has its own 7 Ah accu. The PA can switch from
>> 2.5 W to 10 W :-)
>>
>> Will someone catch the signal at all? At least i'm already
>> asking for RX
>> stations!
>>
>> I'll carry some measuring equipment there, like my M0BMU LF tuning
>> meter, some Cs, a T106-2 and some wire, also a small ferrite core to
>> build a transformer if necessary.
>> What could the feed point impedance be? I have no idea! My modified
>> MFJ-259B covers LF but i expect it will be overloaded with strong
>> signals on the antenna, so i try to match the antenna with the
>> transmitter.
>>
>> More soon :-)
>>
>> 73, Stefan
>>
>> PS: Oh, i'm also going to connect two anti-parallel LEDs to
>> the antenna
>> to see if they shine. It is all a big game for old children!
>>
>>
>> Am 05.09.2018 23:54, schrieb Roman:
>>      
>>> OK Stefan.
>>> Try it to do. may be wonderful results.
>>>
>>> Roman
>>>
>>>
>>>        
>>>> Hello Roman,
>>>>
>>>> Yes maybe i'll build a quick PA tomorrow for LF and will
>>>>          
>> transmit on LF
>>      
>>>> for 24 hours, each 10 minutes, WSPR-2. I have no idea at
>>>>          
>> all how this
>>      
>>>> antenna performs on 137 kHz. Is it still a loop or rather a
>>>>          
>> dipole or a
>>      
>>>> mixture? At least it has about the length of a full size
>>>>          
>> dipole for 137
>>      
>>>> kHz. I would TX at 10 W RF power only, so that a small accu
>>>>          
>> covers some
>>      
>>>> hours. But i'm not yet sure if i can find the time to do it
>>>>          
>> tomorrow.
>>      
>>>> 73, Stefan
>>>>
>>>> PS: If the antenna acts as a dipole, then it is beaming to
>>>>          
>> Russia directly.
>>      
>>>> Am 05.09.2018 21:42, schrieb Roman:
>>>>
>>>>
>>>>          
>>>>> Congrts, Stefan!
>>>>>
>>>>> We are follow by your success!
>>>>> Listen, do you planning to operate 136 kHz, I hear, tell
>>>>>            
>> me pse - do you planing try to TX with that ant on 477 kHz and 160M?
>>      
>>>>> I will be interestin to hear about results.
>>>>>
>>>>> 73!
>>>>> Roman
>>>>>
>>>>>            
>>
>> ---
>> Diese E-Mail wurde von AVG auf Viren geprüft.
>> http://www.avg.com
>>
>>      
>
>