TR 70 H

Transverter for 4m - 70 MHz

69,9 ... 72 MHz

This high performance transverter is designed for the 4m new amateur radio band around 70 MHz. It is based on Kuhne electronic's famous TR 144 H for the 2m band. The TR 70 H features excellent technical characteristics like low noise figure, high linearity and best large signal performance. It is ideal for narrow band operation modes (SSB and CW). The TR 70 H can be modified for professional use. Please contact us for more information!

Oscillator

A temperature compensated low noise butler oscillator generates the local oscillator (LO) signal at 42 MHz. The ambient temperature for the thermostat crystal is stabilized by a 40 °C precision crystal heater. The phase noise of the 42 MHz output signal is -156 dBc/Hz @ 10 kHz. This value is much better than that of the HF transceivers. The oscillator's output power is 100 mW.

Receiver

In the frontend of the transverter, there is only one super low noise amplifier stage with a noise figure of  0.7 dB and an output IP3 of +25 dBm. This provides excellent large signal performance. A first selection of the input signal is done with a low loss bandpass filter in front of the input stage. The first stage is followed by a helical band pass filter and a matching network. A high level schottky diode ring mixer converts the signal to the intermediate frequency (IF) at 28 … 30 MHz. The total gain of the receive path is limited to 25 dB to avoid overdriving of the HF transceiver.

Transmitter

In the transmit path of the transverter a second 17 dBm ring mixer is used. The TX IF input power ranges (0.06 … 1 mW and 1 … 50 mW) can be set with an internal switch.
The TX gain of the transverter can be adjusted with the potentiometer on the front panel. For further power adjustments the HF transceiver can be used. At the mixer output there is a matching network and a helical band pass filter. The following stages are a MMIC amplifier stage, another helical band pass filter, a driver amplifier and the final power amplifier. The available output power is 35 watts. To achieve optimum intermodulation performance, the output power is limited to 20 watts. Overdriving is prevented by an ALC circuit. The output power is indicated on a calibrated meter. A final low pass filter guarantees spurious and harmonic rejection of more than 60 dB.
The transmit unit of the transverter contains a VSWR protection circuit. If the antenna VSWR is bad, the power amplifier switches off for 3 seconds. This is indicated by a red light in the power meter scale.

Sequence Controller

The built-in sequence controller allows time-controlled operation of an additional high power amplifier, a coaxial relay and a preamplifier, which can be placed directly at the antenna. The required connectors are on the back panel of the transverter.

 

Specifications
Type	TR 70 H
Frequency range	69.9 ... 72 MHz
IF frequency range	27.9 ... 30 MHz
IF input power	1 ... 50 mW adjustable / internally switchable to range 60 ... 1000 µW (-12 ... 0 dBm)
LO accuracy @ 18 °C	typ. +/- 2 ppm, max. +/- 3 ppm
LO frequency stability (0 ... +40 °C)	typ. +/- 2 ppm, max. +/- 3 ppm
PTT control	Contact closure to ground
Output power	20 W
IM3 @ 20 W PEP	-28 dBc
	Power amplifier with built-in VSWR protection
Supply voltage	+13.8 V DC (+12 ... 14 V DC)
Current consumption	typ. 6 A (TX)
RX gain	typ. 25 dB
RX output IP3	typ. +26 dBm
Noise figure	typ. 1.5 dB
Case	aluminium
Dimensions (mm)	270 x 260 x 80
IF connectors / impedance	BNC - female / 50 ohms There are two separate IF connectors. They can be switched to one common IF connector
RF connectors / impedance	N-female / 50 ohms
DC supply and control connector	SUB-D 9-pole

Block diagram

 

Connectors