Hi Dimitrios,

Don't forget to consider wire loop antennas for 630m. My QRP set-up has got reports from Finland for 3 autumns running at around 1800km with just a thin wire loop in the garden. With thicker wire it could be at least 3dB more efficient. Larger loops could gain another 6dB at least. They need no ground, are easy to resonate and match, and have useful directivity. 

I am sure a very efficient fixed MF antenna could be made with thick copper pipe without being very big. 

73s
Roger G3XBM

On 3 Jul 2013, at 00:10, Dimitrios Tsifakis <[email protected]> wrote:

  

Hi Dave,

There are no problems here operating portable on 630m. The only
problem with portable operation is that it is hard to provide a low
impedance ground system. At home, I have a number of copper plated
rods and the impedance of my antenna is about 20 ohm, which is great.
When /P though, this figure is always much higher, and that ain't
because the radiation resistance has gone up miraculously ;-)

By the way, I am always amazed by the distance covered by such low
radiated power. Surely this has to do with 630 m but also with the
WSPR protocol. I routinely reach Tasmania, Brisbane and Adelaide with
my low power beacon, and the are all just shy of 1000 km away. I have
also reached a station in Alice Springs, right in the middle of the
country, and that's closer to 2000 km. If there were more listeners
further away, I am sure they would report reception too.

73, Dimitris VK1SV


2013/7/3 Dave G3WCB. <[email protected]>:
    

Hi, Dimitris, LF.

Thanks for posting an interesting article on QRP WSPR. I've been
experimenting along similar lines, but in my case I'm using a QRP Labs
Ultimate 2 kit, which uses the same DDS as your TX, but the WSPR is
generated by an ATmega168 AVR microcontroller. No PC necessary.

With an RF output of about 2 watts into a 5m high "tee" antenna with a 20m
top, I've been consistently spotted at 363km range during darkness by PA3ABK
and PA0A at 499km, with just one spot by DG3LV at 791km range.

My ultimate aim is to assemble a portable WSPR station and hike out to a
remote location, for example Dartmoor, in Devon. I'll need to check to see
if the terms of my licence NOV allow portable operation on 630m first ;-)

73, Dave G3WCB IO91RM

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Dimitrios
Tsifakis
Sent: 02 July 2013 00:39
To: [email protected]
Subject: Re: LF: WSPR-2 on 630m last night


Hi Stefan,

VK dominates WSPR in numbers but not in records -  yet!  :-)

I have been busy with university homework but that's finishing now, so
I will get busy with radio again. My latest experiment is a very
simple WSPR-2 Arduino/DDS/Class-E transmitter. The web page below is
work in progress:

http://people.physics.anu.edu.au/~dxt103/472/wspr_tx/

I have also been doing some tests with a very restricted antenna just
to prove the point that a super large antenna is not the only way to
enjoy the new low bands. Last weekend I did a quick test with the WSPR
beacon from my block of land outside Canberra, using the earth dipole
antenna. I was able to cover 180 km with only 5 W and I know what to
do to improve this. Can't beat a ground antenna when it comes to
convenience!

73, Dimitris Vk1SV

2013/7/2 Stefan Schäfer <[email protected]>:
      

Hi Dimitris,

Am 01.07.2013 06:02, schrieb Dimitrios Tsifakis:

        

Not only it's winter, but I noticed that VK dominates WSPR on 630m on a
regular basis :-)
          

Are you sure? :-)


        

There are plenty of stations monitoring, from all over the country,
including, from time to time, one from Perth, Western Australia.
          

Yes, i see. It is very nice to see so much activity from down under. But
where are all the ZL stations?


        

So far, we haven't managed to repeat the VK1DSH->F6CNI record but
          

perhaps,
      

if the activity keeps to a high level, it's a matter of time until an EU
station is received here.
          

That was a very rare event i guess. But we'll try. Thanks for the
motivation. BTW soon the LF DX season starts again and Edgar has done a
        

lot
      

of effort to prepare for a new #3 DX WR on LF. I'll try to transmit as
        

much
      

as possible, either on MF or on LF. Actually i should really build an
automatic antenna switch. Then i can send a MF WSPR 2 block between the
        

gap
      

of 2 LF DFCW-180 elements :-)

Have fun and good luck!
Any new /p experiments from your side? And how does the tube PA perform
        

now?
      

73, Stefan/DK7FC

        

73, Dimitris VK1SV