[Elecraft] KX2 Satellite Derivative? (Was: Re: The KX2)

[Johnny Siu]

Instead of developing a new radio for SAT.  Can there be a device that can link two elecraft radios for up / downlink of SAT?
In the past, CT16 can link Icom IC275 and IC475 to work as a pair.
I think this route will save a lot of R&D for a new radio.
73
Johnny VR2XMC

      寄件人︰ Edward R Cole <kl7uw at acsalaska.net>
 收件人︰ David Anderson <gm4jjj at yahoo.co.uk> 
副本(CC)︰ Elecraft at mailman.qth.net
 傳送日期︰ 2016年05月25日 (週三) 6:47 PM
 主題︰ Re: [Elecraft] KX2 Satellite Derivative? (Was: Re: The KX2)
   
David,

At 12:43 AM 5/25/2016, David Anderson wrote:
>When I was active on the linear transponders of AO6 through to AO13 
>I never used a satellite duplex radio, always separates. We had much 
>better satellites then, in decent orbits like AO-10. So Yaesu in 
>particular brought out lovely expensive duplex radios. Great! 
>However then the linear sats gradually died and were replaced by 
>digital radio sats. Some FM one channel toy sats, but nothing like 
>the old wide linear transponders.

The FT-736R and other dual-band multi-mode duplex radios were 
produced for the early Heo linear transponder sats - true.  And the 
market for expensive big box radios faded with only single channel FM 
Leo sats.  Understandable that mfrs would go where the market is 
largest.  Kenwood and Icom still market such a radio; Yaesu 
stopped.  But they didn't drop out of the multi-mode VHF radio 
market...just a duplex model.


>Only recently with FunCube and the Chinese Sats have we started to 
>get linear voice transponders back, but again in low fast moving orbits.
>
>Many are now making use of SDR dongles or other SDR receivers as 
>their receiver for sats, because they have many advantages over the 
>old way of just being able to listen to your own receive channel. 
>With an SDR and panoramic can see all of the passband of the 
>transponder or transponders on multiple satellites at once. You can 
>point and click on a signal of interest. Record the whole pass and 
>play it back and see who you missed in the very short pass.  You 
>can run the SDR on a tablet computer in the field, and have more 
>capability than your old FT-736R of olden days.

And my proposal was not for such?  Clearly I stated it should be a 
direct frequency SDR, but married with a transmitter which the 
funcubes aren't.  I mentioned a panadapter and IQ interface to 
computer to support modern sw.


>In short, until we have high orbit transponders on VHF UHF like 
>AO-10/13 no manufacturer is going to produce an FT-736R replacement.

I bought an old FT-736R for more reasons than for satellite.  But 
that should not be confused with my proposal for a KX3-like duplex 
radio.  Certainly one would not compare the KX3 with a 
FT-840.  Totally a different product.  Totally new tech.

>  Any plans for a geostationary satellite would not use VHF UHF, but 
> microwave to get the bandwidth required for a third of the world 
> trying to access it at one time all the time.

Yes, that is true.  That will involve a new mw radio designed for the 
digital modes to be used.  Amsat is cognizant of the fact that hams 
will not be easily do this as was done for AO-40 s-band using surplus 
stuff.  The VHF radio + transverter will not suffice.  The concept 
under consideration includes SDR tech.


>Things have moved on, a single duplex box isn't what is needed.  A 
>transmitter CAT coupled to an SDR panoramic receiver is much better. 
>Point on the screen on the signal you see and with Doppler corrected 
>software set the transmitter you have via CAT to the uplink 
>frequency. It is also magnitudes cheaper.

Is that not what I talked about?  The KX3 is a SDR though limited to 
HF/6m + 2m transverter.  Perhaps a wide-range SDR would be better but 
you still need a comparable transmitter which can operate in 
duplex.  At present this still is a bunch of boxes wired together 
requiring a lot of engineering by the individual vs a complete package.

And such equipment should have more than a single application like 
satellite but instead offer a wide range of VHF+ operational activity 
- so one could buy just one box for doing all.  But you are correct 
that the concept should incorporate newest SDR technology with ample 
use of computing power.  I believe I mentioned all those requirements.

Maybe one can build a wide-range SDR based radio without need for 
transverters.  A SDR that tunes 50-4000 MHz but with comparable 
transmit capability.  I'm not sure that one can do direct freq SDR 
that far with existing tech. One thing to guard against is thinking 
SDR means only a receiver (which current funcube are).

It may be that we are too soon to accomplish that?  The first guy to 
do it will have the market.



73, Ed - KL7UW
http://www.kl7uw.com
    "Kits made by KL7UW"
Dubus Mag business:
    dubususa at gmail.com

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