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[Fwd: [linrad] Homebrew Receivers]

Hello, all!

I screwed up the pa3ckr url. My old eyes could not tell the difference between 'i' and 'l', and as I was using one computer to surf the web and another to write the email, I couldn't cut and paste the url.

The correct URL is: http://www.qsl.net/pa3ckr/hlmixer/

The other URL was OK.

My apologies!


-------- Original Message --------
Subject: [linrad] Homebrew Receivers
Date: Sun, 06 Apr 2003 10:29:56 -0400
From: w3sz <w3sz@xxxxxxxxxxx>
Reply-To: linrad@xxxxxxxxxxxxxxxxxxxxxxxxxx To: linrad@xxxxxxxxxxxxxxxxxxxxxxxxxx References: <CFEIKLJOPPJLBFPEJHKOGEHMCPAA.leif.asbrink@xxxxxxxxxxxxxxxxxxxx>

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

Please note that there may be an antispam preamble to the "replyto"
address. IF so, remove it to reply directly to this message. Thank you!

Roger Rehr
2 Merrymount Road
Reading, PA 19609