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<div dir="ltr">Hi all,<br><br>This topic comes every some time.<br>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.<br><br>73, Maximo - EA1DDO<br><br> <br><br><br><div>> Date: Fri, 23 Sep 2011 10:26:10 +0800<br>> From: phil@pharman.org<br>> To: k5so@valornet.com<br>> CC: hpsdr@lists.openhpsdr.org<br>> Subject: Re: [hpsdr] VHF/UHF downconverter project for HPSDR<br>> <br>> ***** High Performance Software Defined Radio Discussion List *****<br>> <br>> Hi Ante,<br>> <br>> I also have been working on a variant of your B1 solution.<br>> <br>> When initially working on the Cyclops spectrum analyser I tested an Si570<br>> for the second LO (1.126GHz). Whilst this was fine in terms of spectral<br>> purity it did drift quite badly with temperature. For that reason I used<br>> a conventional VCO + PLL system.<br>> <br>> More recently, with Cyclops being re-started, I've been evaluating the<br>> ADL4350 synthesiser chip. This chip contains a 2.2 - 4.4GHz VCO,<br>> integer/fractional N PLL and output dividers. It will provide an output<br>> between 137MHz and 4.4GHz at +5dBm. Whilst the close in phase noise above<br>> 2GHz is not particularly good, in terms of parts count and performance/$<br>> its hard to beat.<br>> <br>> Using similar building blocks to Joe I've built a simple down converter<br>> using Mercury at 60MHz as the IF. Using this IF simplifies the design of<br>> the input filters.<br>> <br>> I'm also experimenting with using multiple IFs so that either a<br>> combination of LO and IF could be found that avoids any images and/or<br>> subtracting the image signal(s) from the wanted signal (when used as a<br>> spectrum analyser). Early tests look very encouraging.<br>> <br>> The use of multiple LO/IF combinations to identify images is not a new<br>> technique. I recall one of the first spectrum analysers I used over 30<br>> years ago had a button you could push in order to determine which of the<br>> signals displayed where images. It was up to the operator to do the final,<br>> visual, signal processing!<br>> <br>> With the speed of modern PCs and FFTs we should be able to automate this<br>> process.<br>> <br>> If there is any interest I'll write this up for the Wiki.<br>> <br>> 73 Phil...VK6APH<br>> <br>> <br>> > ***** High Performance Software Defined Radio Discussion List *****<br>> ><br>> > Hi Ante,<br>> ><br>> > I happen to use a variation of your B1 "solution" on 70 cm EME with<br>> > good results with polarization diversity using an HP-8642B synthesizer<br>> > for the LO, a Mini-Circuits ZAPD-900-5W-S+ splitter to drive two<br>> > MiniCircuits ZX05-C24LH-S+ mixers, followed by the MiniCircuits<br>> > BLP-50+ low pass filters to yield an IF at 10 meters for the HPSDR<br>> > dual Mercury receivers to use.<br>> ><br>> > I could do something similar for my operations at 23 cm EME but I<br>> > happen to use one of DownEast Microwave's 1296/28 MHz transverters<br>> > there, and it works just fine too.<br>> ><br>> > There are many ways to down convert from the VHF and microwave bands,<br>> > of course!<br>> ><br>> > Good luck with your project!<br>> ><br>> > 73, Joe K5SO<br>> ><br>> > _______________________________________________<br>> > HPSDR Discussion List<br>> > To post msg: hpsdr@openhpsdr.org<br>> > Subscription help:<br>> > http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org<br>> > HPSDR web page: http://openhpsdr.org<br>> > Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/<br>> ><br>> ><br>> <br>> <br>> _______________________________________________<br>> HPSDR Discussion List<br>> To post msg: hpsdr@openhpsdr.org<br>> Subscription help: http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org<br>> HPSDR web page: http://openhpsdr.org<br>> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/<br></div></div>
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