Message-ID: <000d01c81c8e$85911230$0d00000a@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <001c01c81c0b$ef981a80$2201a8c0@PC2><E1InMCb-0006LO-Ae@post.thorcom.com><47297997.1208.1CCA4C@dave.davesergeant.com> <20071101082740.18172494@lurcher.twatt.local>
Date: Thu, 1 Nov 2007 13:53:02 -0000
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Subject: Re: LF: RE: 500 kHz report /  Great expectations 
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>>>>.....  No-one will hear you if you can't radiate a signal! .....<<<<



'Steady on old boy', J ,   On the contrary, we can all radiate signals. its 
just that the receiving stations are in the wrong place's ,



I'm sure , during the height of 'beacon bedlam' a lot of stations where 
introduced to  the concept of 'service area'



Birmingham, as the radiation fly's is about 75 miles from my location and 
looks to represent the limit of reliable communications , may be a touch 
less at round the 60 mark. When I can see a trace, I can reduce the power to 
a couple of mW erp and still see the trace, and thats over land ...



After 60 miles, what happens  its anyone's guess,



At the change of state, for want of a better description, there looks to  be 
a 150/250 mile hop, during which time reasonable signals may be expected, 
but once again, if your outside the limits, nothing,  Interestingly, the 
mobile station, who was relaying signal reports, co-incidentally, while I 
ran the 'olivia' data test, reported good signals from his location sw of 
Darby , checking his  location, he was about 100 miles range at 5/600 feet 
asl , that's some 500 feet above my  location ..The trace at Birmingham, had 
all but gone , too close for skip ?  Height help's ?



Later after sunset, falling into a long skip round the 1000 mile mark, 
During which times , good traces can be seen at Shetland and , Wolf has 
posted many 'good'  signal reports, from discussions with those who use the 
band in the past, 1/2000 miles was the expected norm for the northern 
hemisphere and  4/5000 miles for the southern. the north/south allways 
strikes me as 'odd'  Ok, may be a few more watts and reception by-ear  , but 
with the level of digital processing    in use now, looks like 'we' can 
'see' we are living up to expectations,



It's just that we cannot actually 'hear' the other station . !



G ..







----- Original Message ----- 
From: "John Pumford-Green GM4SLV" <gm4slv@sighthound.demon.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, November 01, 2007 8:27 AM
Subject: Re: LF: RE: 500 kHz report


> On Thu, 01 Nov 2007 07:00:39 -0000
> "Dave Sergeant" <dave@davesergeant.com> wrote:
>
>
>> So my only problem is that most people can't hear me! But that is
>> down to the sand below the lawn and the corresponding astronomic
>> earth resistance. Only thing I can do there is to move!
>>
>
> Dave, LF,
>
> The other option is more power of course! If your antenna is
> inefficient due to low radiation resistance you need more current and
> if it's poor because of high environmental losses you need more driving
> power to get the current.
>
> I tried a simple vertical 2 weeks ago in an attempt to eliminate the
> top loading wires for the winter (got tired of them breaking free in
> the gales).
>
> The antenna was 11m with no top-capacity loading and using a
> professional FSM I found that with 80W TX power and 0.9A RF current
> at the feed-point I got an ERP of only 85mW.
>
> I relented and installed some top-loading. With 4 x 7m long capacity
> loading wires running down the upper guys (not a long horizontal
> stretch), and only 30W TX power, I achieved 140mW ERP.
>
> The bare vertical was very inefficient due to low Rrad, as there was
> plenty of current flowing, almost 1A.
>
> The top loading however gave 6dB gain in ERP! I also found the overall
> R dropped considerably with the longer top-load wires (previously I'd
> used 3.5m long loading wires), needing large change in matching
> transformer taps to get back to 50 ohms. The overall losses must be
> lower. Probably due in part to needing much less L to bring it to
> resonance, and fewer losses in the loading coil.
>
> If I couldn't improve the ground losses, which I find I can't either
> (very wet peat on rock isn't great!) I'd put more power into the
> antenna, which I do. I find that with a real "QRP" TX of ~5W I'd not be
> heard by anyone except in the most perfect of conditions. At least you
> have some locals to work I suppose.
>
> My nearest regular stations are Mal and Finbar - both over 600km away,
> even Mark GM4ISM is 500km+ and he's a "GM"!
>
> No-one will hear you if you can't radiate a signal!
>
> I heard Chris G3XVL call/work you on Tuesday and strained my ears, and
> eyes on the waterfall, but could see nothing more than the very faintest
> hint of a signal between his overs.
>
>
> More power Igor!
>
> -- 
> John GM4SLV
> IP90gg
> Clousta, Shetland
>
>
>
>
>
> -- 
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> 10/30/2007 18:26
>
>