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links and more links

HI, All!

Interesting that there should be problems with the links!

The links I posted work fine here. They are:
www.warc.org.uk/cdg2000/introduction.htm .

I have used them on 3 computers with both Netscape and Microsoft Explorer, and they work fine! Google also reports them both as working webpages when I type them in to its search engine.

Maybe there are some less-than-accurate or less-than-up-to-date DNS's out there that some of you use? Maybe there is another explanation...if so, let me know what it is. Maybe it will help me in some of my network play ;)

Since I had the above excuse to post this to reassure you all that the links I gave [with the 'i' to 'l' correction I posted] do work, I would like to give an additional interesting link, as I kknow I am NOT the only one on this list interested in DSP and SDR's in a more general sense.

The link is for Gerald Youngblood AC5OG's SDR-1000, which was featured in the last 4 issues or so of QEX, and which is now available as a Kit.


I checked this link before sending it, and it works here on both Netwcape and Microsoft Explorer and on multiple computers also, just like the other links ;) .

There is also the Discuss-gnuradio list, which has some interesting tidbits from time to time, and which alerted me that the SDR-1000 kit was now available. If you Google Discuss-gnuradio, the first listing will take you right to their information page.


Roger Rehr

Jan Wedin wrote:
Hi all, I also had to search a little to find working links, and here I found useful ones:

Best regards


w3sz wrote:

Hello all,

Just a quick note to those who might be contemplating 'rolling their
own' front ends to use with LinRad. The April RadCom Technical Topics by Pat Hawker G3VA features a variation by I7SWX on the H-mode mixer by G3SBI. With these mixers IIP3's in excess of +40 dBm (up to +55 dBm!!) are reported.

These are, like the mixers Leif shows on his webpages, switching mixers. What the differences are between the H-mode mixers and Leif's design (if any) I am not smart enough to see, except that the transformer configuration appears different with the H-mixers.

These H-mode mixers mixers are also shown in the new ARRL Experimental Methods in RF Design book on pages 5.15 and 5.16, and used in a practical receiver on 6.48 and 6.49. This reference describes this H-mode mixer design as 'perhaps the most exciting work published in the past decade in this area'.

On the web they are discussed by PA3CKR at www.qsl.net/pa3ckr/himixer/

The CDG2000 uses them www.warc.org.uk/cdg2000/introduction.htm
Slightly off this topic, you might also have a look at the LO phase noise specs on that page for the CDG2000.

There is an amusing rant on another list that complains that the writer was able to achieve an IP3 of 'only +40 dBm' with the H-mode mixer. How sad ;)

I'd appreciate any comments to the list by those who can comment on whether they have had experiences with these mixers, and to compare and contrast them with the switching mixers on Leif's pages.

One interesting note is that PA3CKR built one version that used the Minicircuits T4-1 rather than a roll-your-own transformer and the FST3125, and that gave a respectible +41 dBm IIP3 (Input IP3).

Thanks in advance,

Roger Rehr

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Roger Rehr
2 Merrymount Road
Reading, PA 19609