Remember to terminate the IF low freqeuncy port and a least one of the
others with something close to 50 ohms at BOTH wanted and image
frequencies if you want to preserve the full dynamic range and strong
signal handling these are capable of. Use a diplexer filter if
necessary to terminate properly at both frequencies
Andy G4JNT
-----Original Message-----
From: PY3CRX PY2PLL [mailto:[email protected]]
Sent: 2001-02-21 15:30
To: LF Group
Subject: LF: TECH: LF Converters
Hi ...
I've been using a MC1496 as a mixer and decided to try those SBLs from
Minicircuits. But the models that cover down to few KHz are
quite expensive
and not available here.
Re-reading the Minicircuits book I have (from 1993, 700 pages
or so) they
say that for some applications we can use the SIG port as
output and the the
IF port as input when we need to "receive from DC to several MHz".
This is the case below 500KHz for cheap SBL1, SRA1, etc or
even to an high
intercept home made DDBM. The isolation remains more or less
the same, so
the SWR.
I checked this inverting feature on SBL1, SRA1 and TFM2. All
units gave the
same insertion loss (6.5dB) and produced the same LO
attenuation at receiver
input (-45dBc). I use a MAV11 as post amp.
The performance actually is better than the MC1496 bug (less
noise) and 82Hz
ZEVS signal still there, so the regular utilities on 16K,
18k2, 18k3, 19k8,
21k4, 24k0 ... and some new ones between 50K and 100K
yesterday (rtty/msk).
73
Marcus
PY3CRX/PY2PLL
S. B. do Campo - GG66rf
http://py.qsl.br
Active from "DC" to 24GHz
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