[Premium-Rx] mixer fets

[Danny Higgins]

Hi Steve.

I worked for quite a few years in the Racal RX lab back in the 70s and 80s.
The engineer who designed the mixer spent most of his time evaluating new
devices and running a series of comparative tests on a reference receiver.
He didn't find anything better than a set of BSV81s.  These devices come
without the input protection diodes which ruin the strong signal handling
ability.  There is a conductive rubber ring on the devices which needs to be
removed AFTER the FETs have been soldered in place.  I remember forgetting
to remove the rings once, only to be met with the smell of burning rubber
when the board was powered up.

I have an RA3702 and an RA3712.  The 3702 uses BSV81s while the 3712 uses an
SI8901Y module.  The 3rd order intercept point for the 3702 is typically
+32dBm and for the 3712 it is typically +30dBm.

Danny, G3XVR

-----Original Message-----
From: premium-rx-bounces at mailman.qth.net
[mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of engineroom
Sent: 06 January 2013 09:52
To: premium-rx at mailman.qth.net
Subject: [Premium-Rx] mixer fets

Hi Folks,I need to change mixer fets on a Racal RA1792 it has bsv81 type on
the circuit drawing but i noticed some posts on here before mentioning the
sd215de's being used the receiver picks up only strongish broadcasts
stations but passes bite ok i suspect the mixer, it's the later 85830 radio
with score.I was wondering if there is a superior fet replacement or should
i stick with the drawing type?
Regards
Steve in Rugby England
______________________________________________________________
Premium-Rx mailing list
Home: http://mailman.qth.net/mailman/listinfo/premium-rx
Help Page: http://mailman.qth.net/mmfaq.htm
Post: mailto:Premium-Rx at mailman.qth.net
Help Contact eMail:  paul at 8zo.com
Home Page:  http://www.premium-rx.org/