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'[EE] UHF Transmitter availability'
2006\04\11@122545 by Alan B. Pearce

face picon face
Anyone have any suppliers for a UHF transmitter of around 1W output?

Don't know the frequency yet, but it is to go up on Mars as a beacon for an
orbiting satellite to find the lander. AIUI there will be no data
transmission.

Ideally it would be mil-spec, and possibly radiation hard, but I suspect one
could get away with something that was just "rugged".

The frequency range in question used to be used for sounding rockets to
transmit telemetry to ground, but they do not get used these days, so all
the companies that used to make such devices have gone out of business, or
moved on to other products.

My thoughts had run along the line of the devices available for attaching to
machines as an RS232 wireless link, that get mentioned here every so often.
Not sure if they will be rugged enough to withstand launch vibration though.

In the event of not finding anything commercially available, we will
probably have to get the local rf guys to build something. Least then we
would have control over the components used and cleanliness, but if we can
find something commercial to use that is another box ticked, as the saying
goes.

US suppliers fine, as we regularly need to deal with ITARS, which such a
product may well fall under.

2006\04\11@124958 by Bill N8HKI

flavicon
face
Take a look at these guys
http://www.herley.com/


----- Original Message -----
From: "Alan B. Pearce" <spam_OUTA.B.PearceTakeThisOuTspamrl.ac.uk>
To: "PicList" <.....piclistKILLspamspam@spam@mit.edu>
Sent: Tuesday, April 11, 2006 12:25 PM
Subject: [EE] UHF Transmitter availability


> Anyone have any suppliers for a UHF transmitter of around 1W output?
>
> Don't know the frequency yet, but it is to go up on Mars as a beacon for
an
> orbiting satellite to find the lander. AIUI there will be no data
> transmission.
>
> Ideally it would be mil-spec, and possibly radiation hard, but I suspect
one
> could get away with something that was just "rugged".
>
> The frequency range in question used to be used for sounding rockets to
> transmit telemetry to ground, but they do not get used these days, so all
> the companies that used to make such devices have gone out of business, or
> moved on to other products.
>
> My thoughts had run along the line of the devices available for attaching
to
> machines as an RS232 wireless link, that get mentioned here every so
often.
> Not sure if they will be rugged enough to withstand launch vibration
though.
>
> In the event of not finding anything commercially available, we will
> probably have to get the local rf guys to build something. Least then we
> would have control over the components used and cleanliness, but if we can
> find something commercial to use that is another box ticked, as the saying
> goes.
>
> US suppliers fine, as we regularly need to deal with ITARS, which such a
> product may well fall under.
>
> --

2006\04\11@125258 by David VanHorn

picon face
On 4/11/06, Alan B. Pearce <A.B.PearcespamKILLspamrl.ac.uk> wrote:
>
> Anyone have any suppliers for a UHF transmitter of around 1W output?


There's a fellow on Ebay, selling Johnson UHF data radios.
Xtalled.  Item # 9710561106
He has full tech docs..  I have 5 in hand


--
> Feel the power of the dark side!  Atmel AVR

2006\04\11@132822 by Mike Hord

picon face
First ebay sale to travel to another planet?

Mike H.

On 4/11/06, David VanHorn <.....dvanhornKILLspamspam.....microbrix.com> wrote:
{Quote hidden}

> -

2006\04\11@134351 by David VanHorn

picon face
On 4/11/06, Mike Hord <mike.hordspamspam_OUTgmail.com> wrote:
>
> First ebay sale to travel to another planet?


:)

They look like nice units.  If you depopulated the receiver you'd save
weight.
The fact that they're xtal controlled means less problems to worry about.
Synths are noisier, and can do interesting mode-hopping things where they
end up outputting on multiple frequencies while thinking they are in lock.


--
> Feel the power of the dark side!  Atmel AVR

2006\04\11@160821 by Howard Winter

face
flavicon
picon face
Dave,

On Tue, 11 Apr 2006 13:43:51 -0400, David VanHorn wrote:

>...
> The fact that they're xtal controlled means less problems to worry about.
> Synths are noisier, and can do interesting mode-hopping things where they
> end up outputting on multiple frequencies while thinking they are in lock.

The only thing is whether the crystal(s) can survive the vibrations of the flight, and whether it will stay in
tune over the temperature range - unless the craft has the energy budget to keep it at constant temperature,
it's quite a challenge!

Cheers,


Howard Winter
St.Albans, England


2006\04\11@164654 by Wouter van Ooijen

face picon face
> The only thing is whether the crystal(s) can survive the
> vibrations of the flight, and whether it will stay in
> tune over the temperature range - unless the craft has the
> energy budget to keep it at constant temperature,
> it's quite a challenge!

There are lots of issues for spacecraft design that do not apply to
earthbound electronics. Vibration during launch is one, temperature
another. Left alone in space most electronics will simply free to death.
And there is (all sorts of) radiation, but IIRC that is mainly an issue
for certain orbits. If you are going to use redundancy: eliminating all
(or at least the most important) common-cause failures. And lots of
other issues I forgot, it is some years ago now that I was involved in
space stuff. But they are realy going to launch the ERA arm!

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2006\04\11@172836 by upand at them

picon face

This is a joke, right?  Who's sending this up?  Nothing commercially
available would likely survive long in space or on Mars.

Mike


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2006\04\11@174534 by David VanHorn

picon face
>
>
> The only thing is whether the crystal(s) can survive the vibrations of the
> flight, and whether it will stay in
> tune over the temperature range - unless the craft has the energy budget
> to keep it at constant temperature,
> it's quite a challenge!


I used to see a lot of problems with hobby HPR designs, and when you'd look
at the board, they had the main acceleration axis running through the large
face of the crystal.  Those solid motors are pretty rough.

Resonator or R/C clock designs just don't have that problem.


--
> Feel the power of the dark side!  Atmel AVR

2006\04\12@034051 by Alan B. Pearce

face picon face
>This is a joke, right?  Who's sending this up?

No, it is not a joke. My boss is currently preparing a preliminary proposal
to an ESA proposed flight to Mars, which also has as part of the
specification bringing back some real Mars dust.

>Nothing commercially available would likely
>survive long in space or on Mars.

Why do you say that? We currently have a satellite orbiting the moon that
uses commercially available parts.

2006\04\12@034933 by Alan B. Pearce

face picon face
>> The only thing is whether the crystal(s) can survive
>> the vibrations of the flight, and whether it will stay
>> in tune over the temperature range - unless the craft
>> has the energy budget to keep it at constant temperature,
>> it's quite a challenge!
>
>I used to see a lot of problems with hobby HPR designs,
>and when you'd look at the board, they had the main
>acceleration axis running through the large face
>of the crystal.  Those solid motors are pretty rough.

We use Mil-Spec crystals which are built to withstand the vibration. The
unit I have just been working on had the electronics box vibrated at 17G RMS
energy broadband 10Hz-2kHz for 1 minute in each axis. I forget the exact
frequency distribution, but it is shaped over the frequency range.

We don't take any special precautions with the crystal axis, and I don't
know what precautions are taken inside the crystal to ruggedise it.

2006\04\12@074847 by Alan B. Pearce

face picon face
>Take a look at these guys
> http://www.herley.com/

Thanks Bill. Could be in the "starter for 10" category, although a quick
browse of the site suggests most stuff is L and S band. I believe we are
really looking for stuff around the 400-500MHz area.

I think the long term solution will be something built in house, as we do
have a Radio Research Unit as part of the Lab.

2006\04\12@083922 by upand at them

picon face

Okay, wow.  That's cool then.  I guess I was just comparing everyone else to
NASA.

Mike


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