wrote:



I don't much like the receivers I've used in contemporary tranceivers
-- the general coverage synthisized open front end ones. (I hasten to
add I haven't used any of the $4000 rigs; can't afford them). But the
ones I have used seem plagued with near-signal desensitization, front
end overload, etc., and I suppose all that comes from putting the
selectivity so far downstream.

I'm almost tempted to get an old 75s4 and shut up, but I really don't
need another room heater, so, instead, I'm thinking of building my own
receiver along the lines laid down by the late Doug DeMaw in his _QRP
Notebook_. Single conversion 160m superhet with Collins mechanical
filters in the IF and a series of down-converters for the other bands.
Anybody got any experience with the DeMaw Design?

Jim, K5YUT


There was a project to design a REALLY good sigle conversion ham radio and
here is the website:


http://www.warc.org.uk/cdg2000/The%2...ransceiver.htm


It was designed to have a fantastic dynamic range and, after seeing some
of the schematics, it has quite a few good ideas. The mixers and crystal
filters are worth studying.



One of the designers made a helical coil VCO with really good phase noise,
although the mechanical details were complex. These days, I'd want to look
into the AD9954 DDS design.

Probably still have to do something about DDS spurs, but they are fairly
low as is.

==================

So, it seems to me that there are a lot of designs for homebrew gear.
You need to look at your specific requirements to see what will suit you.

In my case, I live in a very RF HOT location, with quite a few powerful
signals. I might take the extra effort to go for maximum dynamic range.
Probably ovekill for most ham locations, but necessary for me.


Jim N6BIU






--

15:10 Pacific Time Zone
Dec 26 2006

International Time
23:10 UTC
26.12.2006