On Mon, 07 Mar 2005 11:13:33 GMT, "Highland Ham"
wrote:

have been examining some surplus mobile telephone base station
equipment and discovered that the 70MHz to 455kHz mixers consists of
2x SA602. Since I've never seen an application using two such items,
my guess it for an image rejection type mixer.
Could somebody please guide me into some notes describing such mixer,
possibly using 2x SA602 (and a crystal osc)
=======================================
Jan-Martin , With 2xSA602 ,are you sure there isn't a 10.7 MHz
'intermediate' IF as well ?

Frank GM0CSZ / KN6WH

Nope, it is shown as
http://www.noding.com/la8ak/12345/images/bd34-rx.jpg
This for NMT450, while earlier NOKIA NMT900 mobile phone BS used
21.4Mz IF as well as 455kHz, while modern 900mc GSM handsets now are
direct conversion. In the actual rig there is a 70MHz xtal filter as
well as 455kHz ceramic filters
The complete page (in Norwegian) is at
http://home.online.no/~la8ak/d28.htm

73, Jan-Martin LA8AK (ex GW5BFV)

---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm