[hpsdr] VHF/UHF downconverter project for HPSDR

[Máximo EA1DDO_HK1H]

Hi all,

This topic comes every some time.
I guess that many of us are waiting for a "HPSDR VUHF Card", so, when a solution be ready, many of us will go for it.

73, Maximo - EA1DDO

                                               


> Date: Fri, 23 Sep 2011 10:26:10 +0800
> From: phil at pharman.org
> To: k5so at valornet.com
> CC: hpsdr at lists.openhpsdr.org
> Subject: Re: [hpsdr] VHF/UHF downconverter project for HPSDR
> 
> ***** High Performance Software Defined Radio Discussion List *****
> 
> Hi Ante,
> 
> I also have been working on a variant of your B1 solution.
> 
> When initially working on the Cyclops spectrum analyser I tested an Si570
> for the second LO (1.126GHz). Whilst this was fine in terms of spectral
> purity it did drift quite badly with temperature.  For that reason I used
> a conventional VCO + PLL system.
> 
> More recently, with Cyclops being re-started, I've been evaluating the
> ADL4350 synthesiser chip. This chip contains a 2.2 - 4.4GHz VCO,
> integer/fractional N PLL and output dividers.  It will provide an output
> between 137MHz and 4.4GHz at +5dBm.  Whilst the close in phase noise above
> 2GHz is not particularly good, in terms of parts count and performance/$
> its hard to beat.
> 
> Using similar building blocks to Joe I've built a simple down converter
> using Mercury at 60MHz as the IF. Using this IF simplifies the design of
> the input filters.
> 
> I'm also experimenting with using multiple IFs so that either a
> combination of LO and IF could be found that avoids any images and/or
> subtracting the image signal(s) from the wanted signal (when used as a
> spectrum analyser). Early tests look very encouraging.
> 
> The use of multiple LO/IF combinations to identify images is not a new
> technique. I recall one of the first spectrum analysers I used over 30
> years ago had a button you could push in order to determine which of the
> signals displayed where images. It was up to the operator to do the final,
> visual, signal processing!
> 
> With the speed of modern PCs and FFTs we should be able to automate this
> process.
> 
> If there is any interest I'll write this up for the Wiki.
> 
> 73 Phil...VK6APH
> 
> 
> > ***** High Performance Software Defined Radio Discussion List *****
> >
> > Hi Ante,
> >
> > I happen to use a variation of your B1 "solution" on 70 cm EME with
> > good results with polarization diversity using an HP-8642B synthesizer
> > for the LO, a Mini-Circuits ZAPD-900-5W-S+ splitter to drive two
> > MiniCircuits ZX05-C24LH-S+ mixers, followed by the MiniCircuits
> > BLP-50+ low pass filters to yield an IF at 10 meters for the HPSDR
> > dual Mercury receivers to use.
> >
> > I could do something similar for my operations at 23 cm EME but I
> > happen to use one of DownEast Microwave's 1296/28 MHz transverters
> > there, and it works just fine too.
> >
> > There are many ways to down convert from the VHF and microwave bands,
> > of course!
> >
> > Good luck with your project!
> >
> > 73,  Joe K5SO
> >
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> 
> 
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