RX-340

The TnTec RX-340 is a receiver with professional features [editor's note: see Performance and practical notes] which adopts a three frequency conversion superheterodyne configuration, the last of which is digitized for all functions as filter and demodulation. It is a mixed technology SDR, conventional in the early stages and numerical in the terminal IF part. The receiver operates with the lower limit of only 5 KHz, thus covering even the lowest radio frequencies, while offering performance in terms of sensitivity and dynamic range stable in the entire range of 0.05 ~ 30 MHz.

This Ten-Tec model in fact it offers a high level precision like a measuring instrument. The measurement of the amplitude displayed by the S-meter, for example, quantifies the tuned RF signal with real accuracy being calibrated in both 'S' points and dBm. The analogue part from the front-end to the intermediate-frequency amplifiers is controlled by an AGC with dynamics of 80 dB. From the next ADC conversion stage signal processing is carried out by a DSP processor that adds an additional 40 dB in automatic gain control, performs a high attenuation slope bandpass filters, PBT, notch, adjustable BFO (in CW within ± 8 kHz in steps of 10 Hz), multi-mode demodulation (also including ISB and synchronous AM).

The TenTec RX340 has 57 different IF bandwidths to choose from a minimum of 100 Hz to a maximum of 16 KHz, the form factor of selectivity is always better than 1.5:1 taking reference points at 6 and 60 dB of attenuation. Many parameters on which there is freedom of intervention. The AGC in addition to three standard profiles, fast, medium and slow, has the ability to construct a user-defined behavior by specifying attack times, maintenance (hang) and release (decay) so as to optimize reception for any mode of communication and propagation condition. The manual control of the RF-gain extends for 120 dB from the combination of analog and digital circuits. The front-end uses eight pre-selection band-pass cells with an octave width, also thanks to this circuit structure the IP2 parameter expresses a very high level. To modify the dynamic range at the input, a 10 dB preamplifier or a 15 dB attenuator can be inserted.

The internal system includes the BITE option, ie Built-in Test, dedicated to perform a functional check of the circuits in order to ensure the full operation of the receiver in all its parts by identifying defects or other. The internal clock uses a high stability TCVCXO with a maximum deviation of ± 1 ppm for a temperature range of 50 °C. The audio benefit from the speaker positioned in the upper panel or from an external speaker for which jack connectors are available both in the front and in the rear panel.

Also on this side there is a fixed level output [600 ohms] for recording systems connection. The volume control is also separate for audio intended for the speaker and headphones. Two RF outputs; the first 45.455 MHz makes the signal available after the 1st conversion mixer and is suitable for connecting devices that display the broadband spectrum around the tuned frequency, while the latter at 455 KHz carries a copy of the signal after processing the DSP and therefore with a bandwidth determined by the user's choice. An input is dedicated for an external frequency reference (master clock) that accepts either a 1, 2, 5 or 10 MHz signal. The receiver automatically adopts this reference, detecting its presence at power up or following any activity of remote control. A standard RS232 interface with baud rates of 75 ~ 38400 bps allows the remote use of the RX-340, this has standard sizes so as to be possibly mounted in a 19-inch rack.

RX-340 performance and practical notes :

In many respects the TenTec RX340 is a superlative radio device, with superior class for reliability and repeatability in performance. This should not surprise, beyond the characteristics that already say a lot this Ten-Tec is a reworking of the project of another top-class apparatus: The HF-1000 of Watkins-Johnson which was one of the first general-purpose receivers to be available outside the military market and to widely use digital signal processing. We are talking about a manufacturer that is aimed at users very different from the radio-amateurs, a sector where robustness and quality as it is understood are not optional but a central part of each realization.

The RX340 is cared for in every detail both in terms of electronics and mechanics. Suffice it to say that the hardware structure, that is the arrangement of the circuits and assembly within the case, is designed to have an extremely limited RFI profile. This means that unlike other devices, the RF signals emitted by the receiver, like the residuals of the display's driver, are minimal, guaranteeing a silent radio-frequency environment. However, if we want to identify a weak point, we have to record the good, but not excellent, dynamic range in the presence of adjacent signals with few KHz offset.

RX-340 price

We have collected for your convenience the Ten-Tec RX340 sale price (Euro) and its trend over time. Useful to guarantee a cheaper purchase of this radio and to put it for sale in the second-hand market. Of course offers, accessories, warranty terms and conditions can lead to different figures.

Price	Date	Condition
EUR 2969.00 (3495USD)	2021-sep	Second Hand In wonderful original condition
EUR 5049.00 (4499GBP)	2019-apr	Second Hand
EUR 2205.00 (2500USD)	2019-mar	Second Hand