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
>
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