Ten-Tec RX-321, Manual

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Rx-321 Receiver
The RX-321 receiver was deisgned by Ten-Tec for OEM applications. It was
manufactured by Ten-Tec under agreement with third parties and never produced with
the Ten-Tec brand name. The RX-321 is based on the RX-320D receiver. Addional
circuitry to support integration with a transmitter was added, along with an RF
preselector and 600 Ohm audio output.
GENERAL DESCRIPTION
The Rx-321 is a general coverage receiver capable of receiving AM, SSB, and CW
signals from 100kHz to 30MHz. The receiver is controlled by an external computer via a
serial connection (see
www.rfsquared.com to download the Rx-320D PC-GUI and
programmers reference guide which will provide more information on controlling and
programming the Rx-321). The Rx-321 is powered from any DC power supply operating
in the range of 12-28VDC and capable of supplying at least 800mA of current (please
observe the correct polarity as shown on rear panel). The antenna connection is designed
for a 50-ohm antenna and is an SO239 type connector. The speaker connection is also
available on the rear panel and is clearly marked. Please connect a 4 to 8 ohm speaker
(again, please observe the correct polarity as shown). Finally, there is also a 9-pin
connector on the rear panel labeled REMOTE. This connector provides an optional 600-
ohm audio output and a mute pin that allows the AGC circuit to be turned off when used
with an external transmitter (this keeps the external transmitter from loading up the AGC
and causing receive recovery problems). Please see the schematic description of the 9-pin
connector labeled remote for the pin out of this connector and DC voltage levels to apply
to the mute pin when using an external transmitter.
SCHEMATIC DESCRIPTION
The receive signals from the antenna pass through one of eight preselector filters that
are selected based on the band in which the receiver is tuned. From there, the selected
signals go through a preamp stage before passing through an IF notch filter and on to the
first mixer. The first mixer translates the tuned signal to 45MHz. The 45MHz signal then
passes through a 45MHz IF filter and gain stage before going to the second mixer. The
second mixer translates the signal to 455kHz. The 455kHz signal then pass through a
455kHz IF filter and gain stage before going to the third mixer. The third mixer translates
the signal to 12kHz where the signal is then passed on to the AD1847 codec and ADSP-
2101 DSP processor for decoding and translating to a low-level audio signal. The low
level audio signal is then passed on to an audio amplifier which amplifies the signal and
passes it on to the external speaker connector provided at the rear panel. An external
speaker can be connected and the received signal can be heard.
Copyright Ten-Tec Incorporated