hello again miles- the FT8800 has a mounted fan and the FT8900 also includes 10 and 6 meters besides 2 and 70cm. There are other rigs to consider as well. 73, pat n2oeq
------- Original Message -------
From : MM[mailto:ka1rrw@yahoo.com]
Sent : 6/4/2007 6:30:01 PM To : patrick.n2oeq@gmail.com Cc : Patrick@yahoo.com; amsat-bb@amsat.org Subject : RE: [amsat-bb] Re: ISS & Amateur Voice Comms (R
Cross Band FM Repeaters:
These are fun devices. We had a 440 repeater (mono band) on Mir that was very popular. And we have been able to on occasions enable the cross band mode on the Kenwood D700, which was also popular. There are a few issues with cross banding that need to be weighed against the popularity.
A typical mobile rig in cross band mode can not handle the high duty cycle of that mode for extended periods of time. Even if you set the power to 5 watts, it would be transmitting continuously for 20 minutes straight as it passed over the USA and Western Europe. In space we do not have convection cooling, hot air does not rise. All electronics in Space on ISS will run much hotter than on Earth. For this type of job you will need commercial or similar equipment designed for 100% duty cycle and it needs to operate with the heat dissipation limitations of zero gravity inside ISS. We already had an Alleged-overheating problem with one radio on ISS and that was at less than 40% duty cycle.
Other limitations:
Frequency: Some countries doe not allow hams to have access to 440, which is why most of the ISS projects are being designed as Mono band projects.
Space: We are short on physical space. No room for big cavity filters.
Repeater suggestions: If some group has the time, effort and Money, they could try to submit a project proposals for a repeaters. Here are some ideas that may be receptive to ariss.
440 uplink, 10 meter down link repeater or visa versa: Benefits, Only minimal band pass cavities will be needed (all transmitters need to exceed commercial TX noise specifications). We have an unused 10 meter antenna presently and 3 440 antennas on the Service module.
440 mono band repeater: Uplink on 435.bottom of band and Downlink on 437.top end of band. (Satellite band on 440 is 435.000 438.000). for the Mir project the DLR team took an Icom repeater and stuffed the filters inside the box. It worked good.
The project will need to fit into a small are and all filters need to be self-contained. Quiet fan cooling and food screens, etc. And you may need to build 5 to 10 working units. One unit will fly in to space the other 9 or so will be given to each one of the training and testing departments in each country.
The new radio I am proposing for voice, packet and SSTV does not have dual receivers or cross band. We just had too many issues with teaching the crew how to use a true dual bander and it just is not worth going through that mess again. Keep it simple, One band active at a time.
73 Miles WF1F
--- Thomas McGrane patrick.n2oeq@gmail.com wrote:
Hi miles- just a short response- I no longer wait to hear the astronauts calling CQ and realize the future operation will be vastly independant of the crew. Considering the almost exclusive use of simple digipeating packet for several years, I have been pushing for cross-band repeater operation to liven things up. Does the digital radio have crossband capability???
Incidentally, the radio I mentioned can be used to monitor both VHF and UHF simultaneously.
Whatever you do, please consider mostly unattended operation aside from use by the crew. I would rather be talking to fellow "space Cadets" on earth than waiting months for nothing.
Thanks, pat
On 6/4/07, MM ka1rrw@yahoo.com wrote:
Hello Patrick, Thank you very much for your comments on the Marex Project proposal. We are always interested in
hearing
pros and cons for all projects and welcome constructive input.
We believe in the slogan Keep It Simple (KIS). When it comes to projects we sometimes Dumb them
down
to make it easier for the ISS crew. Sure these
guys
are very smart, but they do not have time to find
and
read the manuals for the 50+ radio, etc on ISS.
Examples: On Mir Marex flew the Kenwood TM-D7A. This radio
was
used to run the SSTV project and became the
primary
Voice link. This and other Kenwood's have a row
of
Program Mode buttons (I call them function
buttons).
They allow you to save different modes of
operation
and can be very complicated. After reading the manuals several times and testing the PM buttons,
we
decided it would be too complicated for the crew
to
understand these buttons, so we disabled them. Actually I programmed all of the PM buttons to do
just
the same two items, Go To Channel #1 and Set
Transmit
Power to Low. That way if the crew hit a PM
button
they did not have to worry about rebooting the
radio
into a different configuration.
Slow Scan TV: On ISS, Silicon Pixels custom designed software
just
for ISS. We chose them because they had the best solution at the time for SSTV. However, there off
the
shelf version of software "CPIX" wold have been
too
complicated for the crew to understand. There
were
many great features that the ISS crew just would
not
have time to learn. The Silicon Pixels team
developed
a Dumbed down version of software that had just
the
basic features that the ISS crew would need. We
tried
to make it as simple as possibly by deliberately deleting features that were not needed. And we
made
the Buttons big so the crew could hit them easily while floating in Zero-G.
For the new Dual band Radio proposal that Marex
has
put forward, I wanted to again try to Keep it
simple.
I wanted to avoid the problems associated with a
true
Dual-Band radio, such as two volume controls, two squelches and a Band switch etc. The ISS crews
have
been having problems with figuring out a "Function Button" radio verses a Channel knob radio. I
wanted
to go back to 1 channel knob, 1 squelch and 1
volume
control. The Icom ID-800 seems to meet most of our
requirements
for Keeping it Simple. Once we program the radio
on
the ground the ISS crew only needs to know the following controls:
Power Switch Channel Knob Volume Knob Squelch knob.
Instructions for changing frequencies, bands or
Voice
Modes will be as follows. Turn Channel knob to channel XYZ.
Turning on Packet will be as simple as: Turn Channel knob to channel XYZ. Push power button on TNC and look for Green LED on TNC.
Believe me, it's a lot simpler to use than what we currently have in space.
Digital Voice Modes: The ID-800 does support digital voce modes and all normal Analogue FM modes. Since our goal is to
reach
as many people as possible, the primary mode will
be
Analog FM voice. The digital modes wold most
likely
be used for semi-private family communications,
etc.
Deliver Time Frame: This project is not approved at this time. We
only
have approval to continue with the Kantronics
KPC-9612
Modem side the project. Back in the Old Mir days,
the
longest it took me to Pitch a theory to Switch on
was
15 months (SSTV Mir, Pitch theory September 1997, Switch on December 1998). With ISS, it takes much longer. I am tying to use a radio that will still
be
in production when we go into space.
The next project proposal demonstration is
tentatively
planned for Moscow in Late 2007 or early 2008.
Thanks for your input and support.
Miles
www.marexmg.org
--- Patrick McGrane N2OEQ@aceweb.com wrote:
Hi miles- de patrick n2oeq- nice to see you
thinking
of the future. I miss the MIR days. I think there was a simple kenwood dual
bander
on the MIR. I looked at the icom ID800 and my first impression was that it was
not a
simple radio and I am not interested in buying a new digital radio to work
the
ISS. Since there is no rush, please consider other radio models of SIMPLE
design.
Within the past couple of years I purchased a very easy to operate Yaesu FT8800R
dual
band rig capable of cross-band repeat, 9600 baud packet, and narrow FM
operation to
name a few. I looked at several rigs before deciding on it. Of course, it was a personal preference and others may prefer other models but I found this to be my
choice
for satellite work etc.
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