[Wswss] Re: [Mw] Request for conceptual design info--cooperative microwave effort CC-Rider

[Doug McGarrett]

At 07:54 PM 10/8/2005 +0000, Cliff Buttschardt wrote:
>
>This month many highly useful microwave, communications conferences
>are in progress.  I would like to bring to your attention a long term
>microwave satellite experiment that has been around since 2003.  This 
>should interest the groups mentioned above and a few others as well!
>      Many hands make easier work so it would seem that the first step
>would be to segregate a number of small blocks composing the overall
>design.  First, the eventual goal should be mentioned.  The name of
>this 5.7 GHz project is "The CC-Rider" proposed for use on AMSAT's
>EAGLE satellite but equally useful for point to point communications
>due to the simplicity generated by the drift cancellation ability
>built into the system.  Here is the conceptual URL:
>
>http://www.amsat.org/amsat-new/eagle/documents/cc-revisited_paper.pdf
>
>If we were to allocate individual tasks, they might be these:
>1)  5750 MHz local oscillator, 10 mW out with reasonable stability
>2)  5670 MHz low noise preamp
>3)  5800 MHz power amplifier with one half to one watt output
>4)  low noise receiving mixer
>5)  low IMD transmitting mixer
>6)  antenna assemblies, steerable or non steerable such as a patch
>7)  AFC system using a continuous received tone into a standard IF
>As always there are integration tasks that hams do well developing.
>
>Let's conclude by asking that we start thinking about simple ways of
>first assembling such a system using available off the shelf components.
>This might be OEM units connected with SMA connectors for both transmit
>and receive.  Later, a PC board design similar to the "no tune" of past
>years in which the LO, mixers and filters might be placed.  The first
>step is to find simple brassboard assembly suggestions.  This note is
>just that first step.      Cliff K7RR  CUBESAT San Luis Obispo, CA.
>
>


I would guess that the first step is determining what power supply
voltage is available, and at what current.  Everyone responding to the
original post will need to know, at a minimum, the voltage, and
whether or not it is regulated and/or filtered.  If there is more
than one voltage available, then what are they, and what quality are 
they? 

The second specification that needs to be addressed is the operating
temperature.  Is the space vehicle heated?  Anyway, that needs to
be looked at.  Some semiconductors will simply cease to function at
certain low temperatures.  I can attest to that personally.  (I never
could figure out the mechanism, but it was real and repeatable. At
about -15 C, as I remember, these  op-amps typically failed. 
They were QPL, but rated at 0~50 or so, and that's what they did.
Warm them back up again, they worked.  Weird.)

I do not see myself designing anything for the project, but I would 
be happy to critique the designs, if passed by me.  I am a retired 
RF engineer, with some experience in microwave "stuff," most recently 
in the 1 GHz region, but also at 2.4 GHz, and once at 12 GHz (passive).
I don't know anything about space capability, however.   

I should think that a couple of others on this list would be happy to 
do likewise--K2RIW, for one, and Jerry Klekker, whose call I don't 
remember.  When I was working, engineers used to do a review of new 
designs, and every once in a while, we found something that could be 
improved. Not very often--we had good engineers--but sometimes. So a 
second  or third look is worth it. Particularly when you can't go and 
fix it!

--wa2say


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