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Re: RE: Geo Opportunity



On Wed, 30 Jul 2003, Pieter Ibelings wrote:

> Why do you want to use a linear cable TV amplifier? I have never seen a
> cable TV amplifier that can do more than 1 watt or so.

Oh.  I was hoping they were higher power up to say 4 or 5 watts. :-(

> These hybrids are very linear but are normally run with levels of 0dBm
> or so per tone. They can handle 132 channels spaced 6 MHz apart with
> good distortions. The P1 dB is around 28 dBm. Why wouldn't a mitsubishi
> style module work for this?

Those modules are class C, and not usable for linear transponders.

Anyone else have any ideas for off-the-shelf high linearity in the 10W
class?

Bob

> >From: Bob Bruninga <bruninga@usna.edu>
> >To: kgschaffrath@beckman.com
> >CC: amsat-bb@AMSAT.Org
> >Subject: Re: [amsat-bb] RE: Geo Opportunity
> >Date: Wed, 30 Jul 2003 15:54:23 -0400 (EDT)
> >
> >On Wed, 30 Jul 2003 kgschaffrath@beckman.com wrote:
> >
> > > The downlink dosn't look bad. Actually it looks pretty good.
> > > especially if we can get about 10dbw for the transponder.
> > > Its the Up link that would be murder, without any antenna gain
> > > on the sat you would need lotsa kilowatts on the groundstation
> > > to get a reasonable return signal.
> >
> >But, not on 10 meters as the uplink band.  the 14 dB pathloss advantage
> >really helps...  For any discussions please, we need to see the full link
> >budget in any email discussions so we can all see what one is talking
> >about.  Use this format:
> >
> >Uplink 10m
> >TX power         25W    43 dBm
> >TX Antenna Gain          3 dBi
> >Polarization loss       -3 dB
> >Resulting EIRP          43 dBm
> >
> >Path Loss at 10m      -153 dBm
> >Receiver Antenna Gain    0 dBi
> >Received signal       -110 dBm
> >Required for 10dB SNR
> >   in 3 KHz bandwidth  -119 dBm
> >------------------------------
> >Margin                  +9 dB
> >
> >Downlink 2m
> >TX power         5W     34 dBm
> >TX Antenna Gain          3 dBi
> >Polarization loss       -3 dB
> >Resulting EIRP          34 dBm
> >
> >Path Loss at 70cm     -167 dBm
> >Receiver Antenna Gain   15 dBi
> >Received signal       -118 dBm
> >Required for 10dB SNR
> >   in 3 KHz bandwidth  -120 dBm
> >------------------------------
> >Margin                  +2 dB
> >
> >But we still need someone to identify an off-the-shelf
> >ultra-linear Cable TV AMplifier usable at 2 Meters.
> >And how much power is available from them?
> >
> >Bob, WB4APR
> >
> >
> >----
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>
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de WB4APR@amsat.org, Bob

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