[amsat-bb] Re: New To Satellites

[George Henry]

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
> recently..!!)
>
> 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.....
>
> Cheers
>
> 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!

Good luck!


George, KA3HSW