Re: LF: ERP DISTANCE ETC

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Thanks Mal.

Yes, I agree the margin of error is quite large, but trying to measure ERP by taking accurate field strength measurements some 10s of kms away from the QTH seems a reasonable aim to me. I'm learning something by doing this and the inputs today from Alan, Jim and Rik have been very helpful.

BTW, I agree that QRP is often, but not always, successful because of people, like you, 
with good equipment and ears taking the trouble to listen for and work weak 
signals.  I appreciate this. This was certainly the case last winter in my tests on 500kHz. 

Incidentally, I'm sure I'll copy you on 8.97kHz in due course and look forward to your signal when the band becomes available for radiated tests by NoV. Good luck when this happens.

73s
Roger G3XBM

On 11 August 2010 20:13, mal hamilton <g3kevmal@talktalk.net> wrote:

The trouble is that these misleading figures get published and then some think that the world can be worked using uWatts on LF when in fact it CANNOT

Your figures quoted earlier then modified by others all conflict depending on speculation or guesswork, everyone has a go. The outcome is usually as I have previously stated arrive at a figure then it could be plus/minus by up to 10 dB which is a lot, this renders the experiment meaningless.

My argument is not a criticism of individuals and what they do but the misleading figures and calculations produced that could misguide others.

QRP merchants like to get reports from well equipped stations with proper elevated antennas, there is little or no chance of them hearing each other,

In all walks of life there is disagreement, scientist for example.

Building a suitable amplifier to generate 1W erp on 137 Kcs or 10W erp on 500 Kcs would be preferable to watching TV.

I am ready both RX and TX on CW for 8.97 Kcs and would immediately build a suitable rf amplifier if the band becomes available for TX in the UK

I can guarantee you will hear me if you use an elevated antenna suitable for purpose.

 

G3KEV

 

----- Original Message -----

From: Roger Lapthorn

To: rsgb_lf_group@blacksheep.org

Sent: Wednesday, August 11, 2010 6:44 PM

Subject: Re: LF: ERP DISTANCE ETC

Mal,

Thanks again for the great encouragement. Would you prefer we just watched TV instead and gave up the hobby?

Here, I've no interest in running high power on any band, rather I want to see what I can achieve with low power, simple rigs and simple antennas. If this results in my best DX being only 20-30km then so be it.

As for your comment on earth antennas, I beg to differ. There is still a great deal to be explored and understood in this area on all bands from sub-9kHz to at least 500kHz.

73s
Roger G3XBM

On 11 August 2010 18:24, mal hamilton <g3kevmal@talktalk.net> wrote:

Lots of figures appearing on here at present are guesswork and misleading. This has happened in the past trying to guess who was running what power, then the conclusion was + or - 6 to 10 dB wich is nonsense ie could be !W or 4W or !W or 10W. For those complaining about no room for large antennas, use the best elevated antenna you can get up and run several K/Watts to achieve the required ERP.

Earth antennas have also been tested in the past are only useful for Cave radio communications, the wheel keeps being reinvented here on LF.

G3KEV

 

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G3XBM   GQRP 1678    ISWL G11088

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http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM   GQRP 1678    ISWL G11088