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RE: R: Amateur satellites and disasters...



Hi Domenico and all HAMSATs,

>Hi William, PE1RAH
>
>The S band with a small 60 cm dish and 2400 MHz downconverter and uplink
>with a small yagi for 70 cm with 50 watt or 23 cm with 20 watt is the best
>choice for emergency communications via amateur satellite provided you
>have a HEO satellite available like AO40 because the above setup is easily
>transportable and the HEO satellite is usable for many hours per day.
>Remember Rolf DK2ZF and his small transportable station during operation 
>via
>AO40 from the Pacific area ?
>The radio amateurs very active on AO40 from the disaster area where at list
>the following taken from my log and this is not a very small numbar 
>compared
>to the other Region areas.

Unfortunatly, from my practical experience my conclusion is that the L and 
upwards bands are not practical for emergency use, and of use for hams 
outside Europe, USA, and more rich countries in Asia (like Japan, Singapore 
etc).

First I will explain the portable problem. I did many experiments with Ao10 
when it was still active. I wanted to make a small, battery powered 
back-pack station, that I could take almost everywhere on earth. It was just 
a technical goal to find the ultimate combination.
After long testing I made a 2m/70cm back-pack station with a FT290 and 
FT790, just 10W PEP on 70cm and a handheld (arrow-alike) antenna with 7el. 
on 70cm and 4el. on 2m.
With this set I made many contacts... and the funny thing was that it even 
worked with the small-yagi antenna put on a small branch of wood, sticked in 
the earth :o)

With this station I later made a travel through europe, together with ON1DLL 
(now ON5GS), with sat. qso's made from all countries in Europe. Just have a 
look on my website for info and pictures:
www.qsl.net/pe1rah

With S-Band on Ao40 I did also many tests because I also wanted to have this 
band in my portable setup. However it never worked that well as with Ao10 on 
2m/70cm. First problem was the tremendous ERP power needed to get over Ao40 
(on U and L-band), compaired with Ao10. A 50W amp. also needs lots of 
battery power what was an additional problem. The second problem I had was 
the heavy dish. Even 60cm is not easy to carry, or to set up easy and fast 
to the satellite.
I tried some ideas with an inflatable dish, and later a foldable dish what 
was useable but not optimal.

Then there is the financial thing. Even if P3e will have a 1000W PEP, there 
is the need of a downconverter. Most of the hams in Europe, USA can affort 
them, but thats not for the rest of the world where most hams just are able 
to build their HF set. (SHF components are not everywhere easy available on 
the globe).

Then there is also the license regulation problem. In many countries hams 
can not work (or may RX) higher than 2m. Even when they can, they might not 
do it. Maybe you remember that Ao40 several time was swiched to 2m uplink to 
let them use Ao40.


Before some hams misunderstand me I want to make clear that I like to have 
L, S and higher bands on satellite for experimental reasons. However for an 
global emergency radio the easiest and best way is HF, 2m, and 70cm, with HF 
or 2m as uplink. HF because 99% of the hams around the world have it as TX. 
As bought tranceiver, or as kit build, or made themself by old radios :o)

2m ssb is already more a problem, and 70cm is outside Europe, USA, and some 
rich Asian countries not available. (ofcourse there are always a few 
exeptions, I am talking about the majority)
2m/70cm bands can be used as downlink, and with use of a simple 
downconverter kit, converted to the already available HF :o) These kits are 
lot cheaper and much easier to construct without need of SHF equipment... 
The antennas on 2m/70cm is also much easier to construct and adjust than on 
SHF.

But maybe P3e will give some better results than Ao40 on S-band, then it 
might also be usefull as an emergency radio :o) But P3e will also have 10m 
uplink and 2m downlink, what gives us the good old Ao10 feeling back again 
:o)

73 de PE1RAH, William
---

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