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LF: Re: freq: monitor ??

To: [email protected]
Subject: LF: Re: freq: monitor ??
From: "Alan Melia" <[email protected]>
Date: Tue, 26 Jun 2001 23:44:13 +0100
Reply-to: [email protected]
Sender: <[email protected]>
Hi Pascal I am sure you will get lots of answers to your question so I will
reply to you directly.

The secret of 136 operation is in the antenna. Most particularly in reducing
the ground loss to as low as possible. Your 40m dipole with the feeders
strapped and then fed via a loading coil and variometer should work ok. You
will need some work on grounding (earthing....such as counterpoise or buried
earth wires) just like for an HF vertical but it is even more important to
good signals on 136kHz.

Often receiving is the most difficult to solve. Many receivers are
insensitive on 136kHz. You should be able to hear the idle tone of the
German utility Station DCF39 on 138.830kHz at about 20db over S9 (or about
500uV at the input from the antenna) if you system is working properly

Please remember that Steve has been active for about 3 years on LF and has
optimised his antenna system, but his maximum distance on the 'Marathon' was
about 100miles (160kms) In France you do not have many active stations so
you may not be within range of a qso with only 5watts. I would suggest you
should think of at least 50watts, which is fairly easy to generate. In the
early stages as you optimise your antenna and tuning you may find QRSS
operation usefull. It is very much easier to copy in the summer when the
band is full of static. 3 second 'dot-length' QRS can be copied on a
computer DSP with a 0.3Hz filter bandwidth at about 20dB lower level than
audible morse-code. Steve's transmitter has it's uses also for antenna
experiments, and measurements, and is fun if there are stations in range you
can work. Like QRP on other bands, it may not be the easiest way to start
making qsos on 136kHz.

I recommend you look at Rik's web site (I am sure you already have done
this) he has a very good 'tutorial' on antennas and also on DSP reception.
www.qsl.net/on7yd

There is no coordinating frequency on HF for 136. Activity levels are low at
the moment, but most announcements of activity are made on this reflector,
also there is some information via the DX Cluster. My local DX Cluster
distributes 'spots' right across Europe. Some Cluster software allows the
frequenciy to be entered correctly ( 136.5 ) some older software only allows
the 'spots' to be entered at 1800.0 with the detail in the comment field, so
look at both if you decide to use the DX Cluster.

Best activity times are Saturday and Sunday mornings. It was thought that
the best time was early when the noise was low. My propagation studies are
showing that this may not be so. The quietness may be due to a collapse of
the propagation at dawn. Signals are usually quite good from 0700z until
1200z.

Whilst loop antennas may be usefull for a noisy location, or if you have
strong qrm. There is a general agreement amongst the UK amateurs that a good
wire antenna will give a better signal to noise on a very weak signal that a
loop.

It is difficult to retain enthusiasm when you are struggling alone with a
band like 136kHz. Please use the reflector as a 'club' and ask for help when
you need it. There is a lot of experienced operators reading the mail here,
who are available to help you. Dont worry about your English....you would
probably not understand my French at all !!

I am available most of the day and listening most days. Please try to give
us about 24hours notice of your activity period and I am sure there will be
stations looking for you.

73 de Alan G3NYK
[email protected]

-----Original Message-----
From: f6kaw radio club d'ivry <[email protected]>
To: [email protected] <[email protected]>
Date: 26 June 2001 20:25
Subject: LF: freq: monitor ??


From Pascal, F5PNP....



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