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From: Roger Lapthorn <rogerlapthorn@gmail.com>
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Date: Thu, 4 Jul 2013 07:46:21 +0100
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
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Subject: Re: LF: WSPR-2 on 630m last night
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Hi Dimitrios,

Don't forget to consider wire loop antennas for 630m. My QRP set-up has got r=
eports from Finland for 3 autumns running at around 1800km with just a thin w=
ire loop in the garden. With thicker wire it could be at least 3dB more effi=
cient. Larger loops could gain another 6dB at least. They need no ground, ar=
e easy to resonate and match, and have useful directivity.=20

I am sure a very efficient fixed MF antenna could be made with thick copper p=
ipe without being very big.=20

73s
Roger G3XBM

On 3 Jul 2013, at 00:10, Dimitrios Tsifakis <dtsifakis@gmail.com> wrote:

> Hi Dave,
>=20
> 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 ;-)
>=20
> 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.
>=20
> 73, Dimitris VK1SV
>=20
>=20
> 2013/7/3 Dave G3WCB. <ganymede444@btopenworld.com>:
>> Hi, Dimitris, LF.
>>=20
>> 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.
>>=20
>> With an RF output of about 2 watts into a 5m high "tee" antenna with a 20=
m
>> top, I've been consistently spotted at 363km range during darkness by PA3=
ABK
>> and PA0A at 499km, with just one spot by DG3LV at 791km range.
>>=20
>> 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 se=
e
>> if the terms of my licence NOV allow portable operation on 630m first ;-)=

>>=20
>> 73, Dave G3WCB IO91RM
>>=20
>> -----Original Message-----
>> From: owner-rsgb_lf_group@blacksheep.org
>> [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of Dimitrios
>> Tsifakis
>> Sent: 02 July 2013 00:39
>> To: rsgb_lf_group@blacksheep.org
>> Subject: Re: LF: WSPR-2 on 630m last night
>>=20
>>=20
>> Hi Stefan,
>>=20
>> VK dominates WSPR in numbers but not in records -  yet!  :-)
>>=20
>> 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:
>>=20
>> http://people.physics.anu.edu.au/~dxt103/472/wspr_tx/
>>=20
>> 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!
>>=20
>> 73, Dimitris Vk1SV
>>=20
>> 2013/7/2 Stefan Sch=C3=A4fer <Stefan.Schaefer@iup.uni-heidelberg.de>:
>>> Hi Dimitris,
>>>=20
>>> Am 01.07.2013 06:02, schrieb Dimitrios Tsifakis:
>>>=20
>>>> Not only it's winter, but I noticed that VK dominates WSPR on 630m on a=

>>>> regular basis :-)
>>>=20
>>> Are you sure? :-)
>>>=20
>>>=20
>>>> There are plenty of stations monitoring, from all over the country,
>>>> including, from time to time, one from Perth, Western Australia.
>>>=20
>>> Yes, i see. It is very nice to see so much activity from down under. But=

>>> where are all the ZL stations?
>>>=20
>>>=20
>>>> 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 E=
U
>>>> station is received here.
>>>=20
>>> 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 :-)
>>>=20
>>> Have fun and good luck!
>>> Any new /p experiments from your side? And how does the tube PA perform
>> now?
>>>=20
>>> 73, Stefan/DK7FC
>>>=20
>>>>=20
>>>> 73, Dimitris VK1SV
>=20