[amsat-bb] Re: New To Satellites
ka3hsw at att.net
Tue Dec 29 12:01:56 PST 2009
Answers inserted below...
----- Original Message -----
From: "Rupert Hamblin" <rupert.hamblin at gmail.com>
To: <amsat-bb at amsat.org>
Sent: Tuesday, December 29, 2009 12:09 PM
Subject: [amsat-bb] New To Satellites
> Hi All,
> I've had a good look round the forums and on the net generally, I'm
> coming into satellites as a newcomer, having spent
> my past 15 ham years on HF/6M CW/DIGI modes. (with a bit of DSTAR
> So a few questions I hope you can answer and update me....
> i) Generally what power levels are needed to access the birds...?
It depends on the mode. With the current crop of low earth orbiting
satellites (LEOs), only a few watts into a beam will do the job. There are
those who routinely make contacts with 500 mW, but most are probably in the
5 to 25 watt range (there IS a lot of competition). There's no harm in
using more power with the FM satellites, but on the linear birds, use the
minimum necessary to hear yourself on the downlink (obvious caveat:
full-duplex operation is called for), because stronger signals cause the AGC
to kick in, locking out weaker stations. It's common courtesy (and an FCC
rule here in the States) to use the minimum power necessary. And rule
number one is, maximize your RECEIVE capability before worrying about your
uplink. As the old adage says, "you can't work 'em if you can't hear 'em!"
> ii) Antenna's - I've read a lot about the arrow antenna - how good is
> this antenna would you recommend for a new comer ?
The Arrow (2-meter and 70 cm antennas on the same boom) and the Elk antenna
(a log periodic design) are both very good for portable operations. I don't
think the Arrow is recommended for permanent installation, though. Most
portable ops on here use one or the other.
> iii) HT or Base Transceiver - How realistic is working satellites on an
> HT with 5W ? & is base transceiver preferred ?
Many use a 5 watt HT with great success, either with one of the antennas
above, or the Pryme AL-800 telescoping whip. The most important requirement
in an HT for satellite use is the ability to hear yourself on the downlink
while you are transmitting on the uplink. If you search back thru the
archives here, you will find a list of suitable HT's posted within the last
couple of months. Base installations have their own obstacles to
overcome... coax length & routing, lightning protection, and antenna
installation (size, azimuth rotor only vs.full az-el, etc.) among them.
Most of the "base" satellite rigs will operate from 12 volts, so they make
nice mobile/rover/Field Day/demo satellite stations as well.
> iv) Following on from the above - I've read about the FT-2000 or FT-847
> which would be better suited to satellites or another rig ?
You'll get as many different opinions on the "best" satellite rig as there
are rigs out there. Many like the HF/VHF/UHF "all-in-one" boxes, others
prefer dedicated satellite radios like the Icom 910H (myself included).
Many dual-band FM mobiles are quite suitable for operating the FM-only LEOs,
as well. I used to make lots of mobile contacts using a Yaesu FT-8100R
mobile. Some like to go cheap, building their station with older rigs like
the IC-271 or 275 and IC-471 or 475. I started out on the old RS-series
Russian birds (2M up/10M down, 15M up/10M down, and 15M up/2M down) with a
Drake T-4XB, R-4B, and the matching TC-2/RC-2 2-meter transmit & receive
converters, all for less than $600 US...
> v) Obviously a rotator / elevator with a beam(s) will give a better
> performance, but what sort of performance could I expect out of an arrow
> on a tripod with an HT & 5W ?
Again, quite respectable performance can be had with that combination.
Unless you want to hunt for the signal, it's a good idea to print out a
table of the desired satellite's azimuth and elevation throughout the pass,
or get a small computer (Netbook) or tracking app for your cell phone/PDA.
I've made many portable contacts using a 5W HT and a 2-meter beam made of
steel measuring tape (see the picture on my QRZ.com profile page)
> vi) On the HT subject - is it necessary to use 2 HT (one TX / one RX) or
> will just one do ?
You can do it either way... with a full-duplex HT, the Arrow antenna must
have a diplexer installed to combine the VHF and UHF signals, while the Elk
has a single feedline and does not require a diplexer. With 2 HTs, the
Arrow can provide separate feedlines, while the Elk would require a diplexer
to combine the VHF and UHF signals
> vii) ....and finally...some have mentioned that not all the sats listed
> on the AMSAT page are live - where can I get the most upto date list of
> satellites that are active & their frequencies / modes..?
The AMSAT pages are the best source of frequency/mode information, while
http://oscar.dcarr.org is probably the best site for activity information.
> Thats it for now - hope you can help...chances are I may have some more
> questions soon.....
> RH / G0TKZ
You came to the right place to get your answers... there are a lot of very
knowledgeable operators here! Just remember, your station "needs" may not
be the same as anyone else's, so feel free to experiment!
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