Magnum Dynalab 205 "Signal Sleuth" FM signal attenuator / amplifier

Excellent condition cosmetically and functionally.  No flaws that I can detect.  Includes all original accessories and packaging.  (The lights are red.)

From Magnum Dynalab's website:

The SIGNAL SLEUTH brings with it a whole new world of
FM-stereo enjoyment. Whether it be Bach, rock, or current affairs, the SLEUTH
will expand  your world of FM-stereo
entertainment, bringing you more FM stations, more clearly.

 

Also, with the SIGNAL SLEUTH bringing you a cleaner, more
substantial signal, you will experience more of the depth and realism that is
being broadcast from stations with "fine arts" quality, program
signals.

 

Put simply, the SIGNAL SLEUTH ...

•       
amplifies weak FM
signals cleanly

•       
attenuates strong,
harsh signals without coloration

•       
stabilizes FM antenna
(and FM cable) signals

•       
separates interfering
adjacent-station signals

•       
reduces multipath
problems

 

Along with establishing a clearer, crisper sound, a most
important attribute of the SLEUTH is its ability to establish and maintain a
useable FM program signal level. In most cases, this will eliminate the
annoying "flip-flop" stereo-to-mono-to-stereo switching usually
experienced with many FM tuners having non-variable, automatic
"blend" circuits.

 

Easy to install and even easier to use, the SLEUTH model
205 fits neatly into just about any component or integrated receiver system. As
such, it brings all its fine attributes to your fingertips while maintaining a
sleek but unobtrusive demeanor within the system.

Along with adding phenomenal new power to home FM
antennas, from single dipoles to multi-element, stacked arrays, the SIGNAL
SLEUTH 205 features ...

 

•       
signal amplification
variable from -30dB thru +30dB (30 times to gain) to bring weak stations to
full quieting * and tame strong, harsh, local signals

•       
full tunability with
a "hi Q," 600 KHz bandwidth. This adds some 70dB+ in Spurious
Response selectivity

•       
an electronic antenna
switching system to bypass the SLEUTH's amplifier when not needed. Also with
the SLEUTH's direct "in/out" Antenna Signal switching system, instant
A/B comparison is always available

•       
a low profile,
rack-mount style cabinet in satin black

*
"Full quieting" is dependent on the tuner's requirement to establish
a "50dB quieting level."

 

How well does the
Power Sleuth perform?

 

In an independent test, using a commercially available FM
tuner, the following percentile improvements were obtained with the SLEUTH on
line:

 

•       
Sensitivity (under
1dB limiting) -170%

•       
Spurious Response
Rejection -90%

•       
Image Rejection -380%

•       
Ultimate Selectivity
was rated at 70dB+

 

Also, the total harmonic distortion (THD) remained
unchanged, indicating the Sleuth added no measurable distortion of its own.

 

To most, test results mean nothing unless there is some
way to back these results up. One visit to your MAGNUM DYNALAB dealer should
prove beyond a doubt just what the SLEUTH can do for you. Once you've heard it,
there is a very good chance you will begin Rediscovering Stereo FM all over
again.

 

Technical Data:

circuit:  3 high quality rf stages

tuning:  varactor using gold-plated, long-life
controls

gain:  variable -30dB thru +30dB (27dB typical)

tuning range:  continuously variable 87 thru 109 MHz

bandwidth:  600 KHz (hi Q)

noise figure:  better than 4dB

antenna input/output:  75 ohms

max. rf output:  prop. to input but not more than 1.0Vrms

power required:  115vac @ 25 watts

dimensions:  16.0"W x 1.75"H x 5.5"D

weight:  8 lb (3.6 kg)

 

 

Review of The Signal
Sleuth - Model 205

from The Inner Ear
Report

 

This remarkable device does exactly what the name
implies; it investigates FM signals and tracks them. Weak signals are
amplified, thereby offering the possibility of listening to some of the fringe
FM stations that are impossible to receive under ordinary conditions. The
Sleuth works on adjacent channel interference by reducing the strength of the
dominant channel so that the weaker signal can be handled by the tuner. In
other words, the 205 adds gain to the FM signal so that your tuner can use it.
Note that a good antenna (such as the ST-2, as well as a good tuner should be
used to assure acceptable FM reception. If the signal is simply weak, the 205
will do its task very well indeed. When a signal is combined noise at the
receiving end, the 205 will amplify this information as well which may result
in amplified hullabaloo. The Sleuth cannot purify a bad signal -- this is up to
the tuner's capture ratio as well as the antenna's capability to distinguish
noise from signal. However, the 205 can raise the FM signal above the noise
peaks by defining the pass-band and eliminating spurious interference. Weak
signals from distant stations can be amplified by the Sleuth and reception
becomes astoundingly clear if there is no interference close by. If noise
happens to be present around the reception area, the only cure is to find the
source of the noise (it may be a car with dirty sparkplugs, your AC voltage, or
your power line outside). The 205 is not a cure-all device. It simply adds
three more RF stages to a tuner's front end and offers an RF gain control to
regulate potential overloading. The available gain is close to thirty times the
input value. A tuning control additionally specifies the frequency being
selected, hence appropriating attenuation to a narrow band and not to all
frequencies equally. This unique method provides more selectivity. The sound of
the Sleuth is as good as the back-up system, which is to say that it has no
sonic signature of its own. If anything, it defines the common signal, adds
texture and depth to the sound and lets one focus on the program material.
Magnum Dynalab's manual is succinct, enlightening, and provides answers to
questions that linger in every radio listener's mind. To sum up, the 205 is one
those devices that contributes to any critical music system.