Message-ID: <002401c906de$82e26030$0301a8c0@mal769a60aa920>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: 	<000d01c9052d$6f142c30$0301a8c0@mal769a60aa920><C6D17EC6BC594EC7A5CAAF551968B84E@AGB><003e01c90543$b12bb870$0301a8c0@mal769a60aa920><20080823193946.20d4b66b@sighthound.demon.co.uk><005701c90555$0018bcb0$0301a8c0@mal769a60aa920><9256A09B44B94949B34506B5E7260A84@AGB> <20080824233353.muhlmpin3r34kggk@webmail4.kuleuven.be>
Date: Mon, 25 Aug 2008 19:15:10 +0100
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Subject: Re: LF: 500khz rtty
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Rik
My advantage is Location. I am only  2 miles from the sea to the East across 
countryside, to my south there is a river, which probably helps and I am 
sorrounded by thousands of hectares of green fields in all the other 
directions. The only obstacle if any is the town of Scarborough to my SE.
Therefore, my transmitted signal has a good take off and the same applies on 
receive. I have maximum advantage with the permitted power.
Measuring or comparing signals at a distance is impossible, it depends how 
the signal is launched, in an urban environment/middle of a housing estate 
the signal is likely to be attenuated dramatically.
Air calibration at various distances from the TX is the only reliable 
solution. Hardly worth the effort.
The German beacons on 505 khz are strong with me during daytime as well as 
night time, and as a matter of interest I can work most EU stations on 160 
metres daytime when they are active. Antenna on 160 is a one wave inv L at 
over 100 ft vertical, this is one leg of 4 legs for 137 khz.
de G3KEV


----- Original Message ----- 
From: "Rik Strobbe" <Rik.Strobbe@fys.kuleuven.be>
To: <rsgb_lf_group@blacksheep.org>
Sent: Sunday, August 24, 2008 10:33 PM
Subject: Re: LF: 500khz rtty


Based on the antenna description given by Mal ("1/4 wave inv L for 500
khz, 100 ft vertical and rest horizontal") simulation reveals a
radiation resistance of 5 Ohm and a directivity of 1.5 dBd. This means
that only 375 mA antenna current is needed to radiate 1 W ERP.
It is hard to tell from here, but such a big antenna should have a
loss resistance of 20 Ohm or less. So in the worst case 2.8 Watt TX
power is needed to get 1 Watt ERP.

I can only dream of such a situation ;-)

73, Rik  ON7YD - OR7T

> From: "mal hamilton" <g3kevmal@talktalk.net>
> Sent: Saturday, August 23, 2008 8:18 PM
> To: <rsgb_lf_group@blacksheep.org>
> Subject: Re: LF: 500khz rtty
>
>>
>> ANYTIME . If you saw the fet in my PA you would'nt bother.
>> G3KEV
>>
>> ----- Original Message ----- From: "John Pumford-Green GM4SLV" 
>> <gm4slv@sighthound.demon.co.uk>
>> To: <rsgb_lf_group@blacksheep.org>
>> Sent: Saturday, August 23, 2008 7:39 PM
>> Subject: Re: LF: 500khz rtty
>>
>>
>>> On Sat, 23 Aug 2008 18:14:23 +0100
>>> "mal hamilton" <g3kevmal@talktalk.net> wrote:
>>>
>>>> I thought that would be the response from you. Why no ID?
>>>> I will let OFCOM decide if necessary
>>>> G3KEV
>>>
>>> Perhaps we could ask them to check your ERP at the same time?
>>>
>>>
>>>
>>> No virus found in this incoming message.
>>> Checked by AVG - http://www.avg.com
>>> Version: 8.0.138 / Virus Database: 270.6.6/1626 - Release Date: 
>>> 8/21/2008 6:54 PM
>>>
>>>
>>>
>>
>>
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus   Database: 
>> 270.6.7/1628 - Release Date: 8/22/2008 18:32
>>
>>
>>



Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm



No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.138 / Virus Database: 270.6.7/1629 - Release Date: 8/23/2008 
1:16 PM