[Premium-Rx] FST3125 mixer

[Carcia, Frank A. HS]

Hi,
I bought the parts but have not built the mixer yet. I would also be
interested in real performance. The VCC is higher than normal and
I could see possible problems with layout and bypassing. I've seen
some mixers like this with magic beads in the ground lead. All this
could lead to unstable operation and ground bounce. These parts are very
fast
and could have problems with oscillation. ACTQ parts fixed some of the EMI
problems but raised the source Z. Thank you for your observation. fc

-----Original Message-----
From: W.J. Ubbels [mailto:w.j.ubbels at student.tudelft.nl]
Sent: Tuesday, July 15, 2003 10:03 AM
To: premium-rx at ml.skirrow.org
Subject: [Premium-Rx] FST3125 mixer


Hi all,

This may be a bit off-topic, but I thought I'd ask:
Is there anyone on the list who has experience in using the FST3125 H-mode
mixer in an up-converting HF receiver design, with an LO from say 45  to
75MHz (and a 45MHz IF)?
I have built such a mixer myself, but I am not satisfied with the results
when using it at input frequencies of 25MHz and up. I have noticed a lot of
noise coming from the mixer which is then fed down the IF chain when
listening at these frequencies. It appears to me like some kind of
oscillation in the mixer or its driver (74AC86). Any help is appreciated.

Regards,

Wouter PE4WJ


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