[amsat-bb] Re: Full band transverters for satellite operations?

Tony Langdon vk3jed at gmail.com
Tue Jun 12 13:26:02 PDT 2007

At 12:47 AM 6/13/2007, Alan P. Biddle wrote:
>With the advent of rigs like the FLEX-5000, features are becoming available
>which exist in no traditional rig.  However, for operation on VHF, UHF, and
>microwave frequencies, you are obviously going to need a transverter.  Using
>a 28-30 MHz IF, you can cover 2 meters with 2 LO crystals.  However, once
>you get to 70 cm, it would take 15 crystals to do this.  Now admittedly, you
>wouldn't necessarily want to cover the entire band, as an FT-847, TS-2000,
>etc do.  But you would want more flexibility than just one or two 2 MHz
>segments for both space and terrestrial operations.  More if you wanted to
>include basic FM repeaters.

Well, as someone else suggested, lowering the IF would give you more 
bandwidth to play with.  Even better, some SDR designs also have the 
ability to do undersampling, where a narrow (relatively) bandwidth 
that is much above the sampling rate can be accurately sampled ( 
conceptually, it's like the sampling is also the first mixer).

It appears that the HPSDR hardware will be capable of undersampling, 
possibly into the UHF region.  I'm hoping to find out for myself 
later this year when the Mercury and Penelope boards become available. :)

With the right SDR hardware and configuration, transverters may not 
be needed until you go beyond 70cm.

73 de VK3JED

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