Preselector Layout and Graphics
This page features some examples of preselector construction and front panel graphics.
These models represent various stages in the development of the final circuits for HF, MF, and LF
frequencies, which can be found elsewhere on this site.
I suggest using the front page index of this site for further navigation to the various
preselector projects and schematics.
TYPE-1     A three-piece signal pre-conditioner built into 19 inch rack mount panels.
The first unit is the actual preselector and antenna switch selector. This includes the (now) requesite "Lengthen" - "Shorten" - "Band Pass" switch function.
The second unit is an impedance-matching tuner (transmatch), with in/bypass switch. To the right is a MMIC (MAR-6) pre-amplifier and on/bypass switch. It should be noted the rear panel of this unit provides coax connections for the tuner to be inserted into the signal path directly after the antenna switch (above) and ahead of the attenuator. This allows the transformation and adjustment of the raw antenna impedance to match the subsequent components in the chain, or as the other units, it may stand alone.
This third unit is a receiver selector and RF attenuator. Note that the selector has positions for disconnecting the RF signal as-well-as muting the receivers' audio lines (hiss and noise elimination).
TYPE-2     A single unit, stand-alone preselector/preamplifier combination.
This unit also uses a MMIC amplifier. It is fairly portable, being only 9 inches wide. The "trim" control is a small value capacitor, thus the "multiplier" control.
TYPE-3     A single unit, tuner, preselector, notch filter, preamplifier combination.
Another 19 inch, rack mountable unit. This device has all the bells & whistles, including a notch, or null, filter stage. There are closeups of the front panel and internal construction elsewhere on this site.
TYPE-4     Another single unit, stand-alone preselector/preamplifier combination.
This unit uses an FET amplifier. It is also fairly portable,and is 8 inches wide. This is the one that will travel to New York City with me on my business trips.
TYPE-5     Kind of a smaller type-3 preselector/preamplifier combination.
29 Sep 06
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