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Re: P3E Microwave Frequencies



----- Original Message -----
From: "Stan" <stan@capecod.com>
To: <amsat-bb@amsat.org>
Sent: Sunday, May 11, 2008 4:28 PM
Subject: [amsat-bb] P3E Microwave Frequencies

> Hello The Net:

> plan for P3E.
>
> I am starting to plan for Microwave receive only down converters and
> transmit only up converters.
>
> How firm is the frequency for the X band downlink at 10,490 MHz  ?
>
> Ditto for the L2 uplink of 1,263 MHz  and S band uplink at 2,447 MHz ?

Hi Stan, W1LE

For the uplink in  L1 and L2  of AO40 I have used  homebrewed transmit
converters to cover 1268-1270 MHz with an IF 144-146 MHz but for P3-E
the L1 must cover 1268-1270 MHz while the L2 must cover 1260-1262 MHz

The L1 is the old uplink from 1268-1270 MHz on AO40 and it will continue
to be used for P3-E if we amateurs we don't interfere with the new Galileo
satellite-navigation-system that will use part of the 1268-1270 MHz band

The L2  is the uplink from 1260-1262 MHz and it will be used as a Galileo
alternative "only ?" if we amateurs will interfere with the Galileo system.

By the way using transmit-converters with a 144-146 MHz  IF will produce
interference while receiving in 2400-2402 MHz using a downconverter with
the same IF between 144-146 MHz

For the above reason and for the 23 cm transmit-converter I have changed the
IF to 146-148 MHz using the following XTAL's with the followig
multiplication and conversion.

L1
LO  XTAL:            93.500 MHz
Multiplier              93.500 x 12 =1122 MHz

Conversion             1122 + 146 =1268 MHz
                                1122 + 148 =1270 MHz

L2  (Galileo alternative)

LO XTAL               92.833333 MHz
Multiplier              92.833333 x 12= 1114 MHz

Conversion             1114 + 146 = 1260 MHz
                                1114 + 148 = 1262 MHz

Using the above transverter setup with a linear amplifier both antenna
mounted there are no problems if only the L1 or only the L2 will be
used extensively for long periods of time but if unfortunately P3-E will
be scheduled to go one day in L1 and another day in L2 then using
transverters we loose the frequency agility because at every change
we must tune again the multipliers and the linear amplifiers over the roof.

Tanks to the S/X-P3E/P5A-team the X band linear downlink of P3-E will
be 10451.000 MHz centered so that it will be possible to reuse the old
10450-10452 MHz dowconverters already built for AO40 but never
used for it.

My homebrewed 10450-10452 MHz downconverter uses a 146-148 MHz
IF with a 107.333333 MHz XTAL as follows:

First multiplier     =     107.333333 x 24 =  2576 MHz
Second multiplier =     2576 x 4               =  10304 MHz

Conversion           =       10304 + 146       = 10450 MHz
                              =       10304 + 148       = 10452 MHz
>
> I am starting to look at possibilities of a common Local Oscillator (LO)
> for some of the bands, but I am having no luck. Having a common LO or at
> least
> parts of a LO multiplier chain, would economize and maybe lend
> themselves to being PLLed
> to the station 10 MHz reference.

I believe it is a difficult task considering all possible "birdies" falling
into the different bands.
>
> Has anyone come up with common LO and IF schemes for multiple P3E bands ?
>
Long time ago I have seen a project over a  ARRL Proceedings Microwave
Update for OSCAR-13 but I have to look for it.
>
> My IC-910H will cover 1,263 MHz nicely, but it looks like all of the
> other higher
> bands will have a unique LO for the band, at least for X band and below.
>
I believe that in real life from the point of view of the frequency agility
your IC-910H is much better than using separate transmit-converters and
down-converters covering from 2 meters to 23 cm

>From 13 cm and up to the X band the downconverters and transmit-comnverters
are mandatory

> Time to get ready....
>
> Stan, W1LE   FN41sr   Cape Cod
>
I agree

Have fun and 73" de

i8CVS Domenico



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