TR 432 H

70 cm Transverter with excellent large signal performance

432 ... 434 MHz

Over 25 years of experience in development of new transverter technologies led to this masterpiece of VHF technology. Implementing technological innovations and expertise in a timely manner and combining them into a state-of-the-art product is a thing we have succeeded in doing in a very impressive way. It's a challenge for us to extend the limits of what is technically feasible and to put this into our products. Ranking first worldwide and improving our products continously are a matter of course for us.

Introduction

The new design of our 70cm transverter for 432 MHz features better performance and new functions.

An external 10 MHz reference frequency can be connected to achieve highest frequency accuracy now. This is necessary for EME and WSJT. The frequency of 10 MHz can be supplied by a highly stable OCXO, a reference oscillator of a frequency counter, a rubidium frequency standard or a GPS controlled frequency source.
The new version of the 70cm transverter TR 432 H also includes the switches to configure the IF connectors of the transverter. The TX IF input ranges and the IF connector configuration can be done with the internal switches of the transverter. So the transverter is compatible to most of the used HF transceivers with transverter output. The drive gain control on the front panel is standard now.

Oscillator

A temperature-compensated low noise butler oscillator generates the 101 MHz LO signal. A thermostat crystal with a 40 °C precision crystal heater is used. The phase noise of the multiplied oscillator signal with a frequency of 404 MHz is  -140 dBc/Hz @ 10 kHz. This value is better than that of the HF transceivers. The oscillator output power is more than 50 mW.

Receiver

In the receiver frontend there is only one balanced super low noise stage. A noise figure (NF) of 0.8 dB and an output IP3 of 37 dBm are achieved. To prevent interference in case of multi-band operation, there is a bandpass for the 70cm band at the input. The prestage is followed by a high-Q helical filter and a matching network. A high-level double-balanced ring mixer with an IP3 of 30 dBm converts the signal to the intermediate frequency (IF) at 28 … 30 MHz. The total gain of the receiver path is limited to 20 dB to avoid overdriving of the HF transceiver. An internal preamplifier of the HF transceiver has to be switched off. The transverter provides excellent large-signal performance. Gain and sensitivity are ideal for contesting and DXing. For EME operation the use of the preamplifier MKU LNA 432 A is recommended. This drops the total noise figure to 0.5 dB. A second N-connector permits the use of a separate cable for the
preamplifier.

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. Two helical band pass filter ensure best spurious rejection. The mixer output signal will be amplified with two MMIC amplifier stage. LD-MOSFETs are used in the driver amplifier and the power amplifier. To achieve optimum intermodulation performance, the output power of the oversized power amplifier is limited to 20 W. Overdriving is prevented by an ALC circuit. The transmit unit of the transverter has a protection circuit. If the antenna SWR is bad, the power amplifier switches off for 3 seconds. This is indicated by a LED. A final low pass filter guarantees spurious and harmonic rejection of more than 60 dB. The output power is indicated on a calibrated meter.

Sequence Controller

The built-in sequence controller allows time-controlled operation of a high-quality power amplifier and a coaxial relay with a preamplifier, which is placed directly at the antenna. The required connectors are on the rear panel of the transverter.

 

Specifications
Type	TR 432 H
Frequency range	432 ... 434 MHz
IF frequency range	28 ... 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 (without 10 MHz reference frequency)
LO frequency stability (0 ... +40 °C)	typ. +/- 2 ppm, max. +/- 3 ppm (without 10 MHz reference frequency)
PTT control	Contact closure to ground
Output power	20 W
Supply voltage	+13.8 V DC (+12 ... 14 V DC)
Current consumption	typ. 6 A (TX)
RX gain	typ. 20 dB
IP3 out	typ. +30 dBm, min. +27 dBm
Noise figure	typ. 1.8 dB
External reference input	10 MHz / 2 ... 10 mW
IM-Dynamic	typ. 98 dB SFDR @ 3 kHz BW
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