Hi Anthony.

The way that I use it on the two radios that I have is to tune in the
frequency so that the signal is centered on the AM mode, and then switch to
the synchronous detector.  I find that tuning in AM with the narrowest
filter available is usually helpful so that you can judge where the center
of the signal is more exactly.  Sync detectors work best if you are tuned
very closely to the carrier frequency.  What sync detectors are useful for
is listening to signals that are getting selective fading as often happens
during the nightime at the upper end of the medium wave broadcast
band.  Often when such fading is occurring, one sideband and the carrier
may fade while the other sideband fades to a lesser degree or not at all,
causing the signal to sound momentarily distorted.  Synch detectors are
really good at filling the missing carrier back in.  They also are helpful
in raising signals that are near the noise floor up a bit for better
intelligibility--at least that is what happens on my Drake and on the Sony
2010.

These detectors have their limitations also.  If you have a radio that
tends to drift, than you will find the synchronous detector to be worthless
because if you drift a few hundred hertz off frequency, your synchronous
detector will go out of lock, and you will hear a heterodyne on the signal
that you are attempting to listen to.  Also, if your radio has passband
tuning, as my Drake does, it is important to have the passband tuning
centered up as off-tuning the passband tuning will also pull the
synchronous detector out of lock.

As for the '7600, I can't tell you--I never owned one.  The only radios I
can vouch for are the Drake R8A (and I assume the R8B is just as good), the
Sony ICF-2010, and the Lowe Research HF150.  The Drake and the Lowe
Research radios are first rate radios, while the Sony is still quite good,
but not quite in the same league with the "big boys."  My only regret with
all of these radios is that there is no voice frequency readout--hence, my
interest in the Icom R75.

73, de Lou K2LKK

  At 07:45 AM 1/7/2005 -0500, you wrote:
>Hi Lou;
>
>Pardon my ignorance but, how do you use synchronous detection.
>
>I have never been able to master it.
>
>And, do you know how good the synchronous detection is in the Sony 7600?
>
>73 De Anthony W2AJV
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Louis Kim Kline
A.R.S. K2LKK
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