UHNE electronic GmbH

MICROWAVE COMPONENTS
 10 GHz Transverter MK2
DB6NT 07.2002
3.Generation

1.Introduction

In 1977 the Dubus magazine puplished the first 10 GHz SSB transverter wich had been
developed by Claus Neye, DL7QY. This was the begin of using narrowband techniques in the
3cm band. The construction technique at that time utilised the classical waveguide aproach.

During the eighties several descriptions of modular approaches (LO, mixer, Amps) in
seperate boxes were puplished (2. Generation).

The current transverter is a singleboard construction on RO4003 substrate. The reciever has a
noise figure of 1.2 dB and the transmitter achieves an output power of more than 200mW.
The IF is 144MHz and the spurious rejection is better than 40dB. A 432MHz IF can be
selected just by change of the crystal in the XO. Then the spurious rejection is even better at
least 50dB.
Everything -TX, RX, LO, IF-Switch and T/R-control is on a single board housed in a
55x148x30mm large box from tinplate. Tuning is required only for the two cavity resonators,
the four helix bandfilter in the LO-chain and the bias currents of the TX/RX amplifiers.
The restricted tuning range of the helix filters make „false“ resonances not possible.

2.Description

LO
The proven „simple“ XO uses the FET SST310 in a grounded gate circut. The crystal
frequency for a 144MHz IF is 106.5MHz. The coil is tuned by a M3 brass screw, which is
fitted instead of the usual ferrite tuning screw. A heater which is mounted on a 40° C
thermostat crystal stabilizes the crystal temperature and keeps the frequency drift in limits.
Extra pads are provided for fitting additional capactitors which can be selected for
temperature compensation. For normal use in a restricted temperature change environment the
stability is sufficient. But for more serious work a special outboard solution like the OCXO
from DF9LN is required. This can be fed in at the source of the SST310, as indicated in the
circuit diagram. The crystal has to be removed in this case.

The XO is followed by a tripler to 319.5MHz which utilises a BFR92A transistor. The third
harmonic is filtered by a helix bandfilter and drives the doubler with the BFP196. The output
filter sieves the harmonic at 639MHz.
A second doubler with a BFP196 achieves an output frequency of 1278MHz. After another
helix bandfilter on 1278MHz a further doubler with a BFP196 achieves an output frequency
of 2556MHz. A helix filter is used for selectivity.

Now the chain of bipolars ends and the 2.5GHz signal drives a GaAs-FET quadrupler with a
MGF-1907. A microstrip edge coupled filter selects the LO frequency of 10224MHz and
drives a further linear amplifier equipped with the MGF-1907. The power at this point is
around 5mW (7dBm).
Mixer
The LO drives a single balanced diode mixer which uses a BAT15-99 low barrier double
diode. The IF-port of the mixer is terminated by selectable attenuators for transmit and
receive. These are switched by PIN-Diodes BAR64-03W to a common IF-connector.

A voltage of at least +9V, which can be supplied by a FT-290 for example, activates the T/R-
switching. Other brands of 2m tranceivers have to be modified accordingly.

Whilst this method of T/R- switching via the IF coaxial cable is quiet elegant, also a separate
method via the PTT-MAN input can be acomplished.

An extra output is fitted for TX+, which can be used for external coaxial relays or PAs. This
output must be guarded by a 0.63A fuse. It is not save in case of short circut !

On the RF- Port of the mixer a cavity resonator cares for sufficient suppression of spurious
responses.

RX
The RX-chain uses two HEMT-Amplifiers (NE32584C) and a third stage with a MES-FET
(MGF -1907).
The gain of 30dB renders an extra IF- amplifier obsolete. The stages are coupled with simple
microstripline filters. The last stage is coupled to the mixer filter via a Wilkinson divider.

TX
Two stages with MGF-1907 follow the Wilkinson divider. A subsequent cavity resonator
cares for additonal selectivity in the TX-chain needed for suppression on the LO.

Two further stages with a MGF-1907 and a MGF-1601 amplify the signal to a power of
200mW. A directional coupler with a BAT15-03W Schottky diode allows for a monitor volt-
age of the RF output power.

3.Construction

To achieve a successful construction of this transverter the builder has to have

experiences in the use and handling of SMD-parts. Furthermore experiences with
smaller projects in microwave circuits are valuable. In any case the construction of this
transverter is not a beginners project.
The usual ESD protection measures should be obeyed. (see(5) for an execellent survey).

Construction Steps

1. Solder the walls of the tinplate box and trim the PCB for fitting into the tinplate box.
Please caution! Be careful. The tinplate has sharp edge, do not hurt you!
2. Mark the holes for the SMA-connectors

3. Drill holes for SMA-connectors and feedthrough caps

4. Solder PCB into the box (Fig.4). Use a 10.2mm high piece of wood as a ruler to find
the right adjustment.

5. Solder the coupling rivets for the cavity resonators. They must stand upright.

6. Tin the bottom of the resonators. Mark the correct position with a pair of dividers. Fit a
short M4 screw to the resonator. Put the resonator onto the position marked and heat the
screw with a soldering iron. If the resonator is on the right temperature solder at the
bottom.

7. Mount the parts onto the PCB (Fig. 3). Mount the feedthrough caps. Solder the helix filters
(Fig.4). Solder the regulators with their heatsing to the wall of the tinplate box. Clean the
finished PCB with alcohol. The tuning screws of the resonators should be removed. Dry the
module in a stove (1h at 80° C) or over night lying on a central heating.

4. Alignment

The following steps are necessary for the alignment:

1. Apply 12V. Use a current limited (< 0.6A) power supply. Check the voltage at the output
of the fixed voltage regulators.

2. Measure the collector voltage at the BFR92a. Turn the tuning screw of the oscillator coil
until the decrease of the collector voltage indicates the proper oscillation. The measurement
should read around 7V.

3. Measure voltage at M1 (Fig. 2). Tune bandfilter F1 (319.5 MHz) to minimum voltage ( ca.
6V) at M1.

4. Measure voltage at M2 (Fig. 2). Tune bandfilter F2 (639 MHz) to minimum voltage ( ca.
5V) at M2.

5. Measure voltage at M3 (Fig. 2). Tune bandfilter F3 (1278 MHz) to minimum voltage ( ca.
5.3V) at M3.

6. Measure voltage at M4 (Fig. 2 ). Tune bandfilter F4 (2556 MHz) to maximum voltage

( ca. 4.5V) at M4.

7. Adujst 10k pot for a reading of 4V at the drain of the MGF1902 (LO-Amplifier).

8. Connect dummy load or antenna at input connector of RX.

9. Adjust bias for the HEMTs for a reading of 2V at their drain and for the MGF1907
for a reading of 3V at its drain.

10. Connect 2m receiver at IF connector. Turn RX-Gain and TX-gain pots fully CCW. Adjust
 M4 tuning screw at resonator in front of mixer slowly clockwise (inwards) until you ob-
serve an increase in noise level. This is the upper sideband on 10368MHz. For verification
turn the tuning screw further inwards until you observe a second peak in noise level. This
is the lower sideband on 10080MHz. Turn back to the first maximum (Tuning screw is less
inside the resonator) and lock with the security nut.

11. Switch transverter to transmit by grounding the PTT input. Connect a 50Ohm dummy
load to the TX output. Adjust all FETs in the TX-chain by the appropiate bias pots to the
drain voltage given in the circuit diagramm (Fig. 2). Drive the transverter with 1...3W on
144 MHz. Measure the monitor voltage at MON out. Only adjust the resonator in the TX-
chain to a maximum by careful tuning. There is only one maximum, because the first reso-
nator has already been tuned in the step before. Lock he tuning screw with a security nut.
A fine tuning can be carried out by optimising the first resonator (in front of the mixer)
and the bias currents of the TX transistors.

12. Reduce the TX-gain by clockwise rotation of the TX-gain pot until the TX output de-
creases.

13. Connect antenna to RX input. Adjust the XO until a known beacon reads the correct
frequency.

14. Take low resistance carbonised foam and glue it into the bottom cover. This damps
resonances possible.

That`s all.

5. Acknowledgement

My special thanks to Lorenz, DL6NCI. His support and the discussions were mandatory
for the success of this development. Also my thanks to Richard, DF5SL, to Gerd, DG8EB,
and to Jürgen, DC0DA, who verified the reproducibility of the design by building this
transverter.

6. Literatur / References:

(1) Michael Kuhne, DB6NT, „Simple 10 GHz Transverter“, DUBUS Technik III,
DUBUS Verlag, pp. 324-336

(2) Michael Kuhne, DB6NT, and Uwe Nitschke, DF9LN, „LNA for 10 GHz“, DUBUS
Technik V, DUBUS Verlag, pp. 191-195

(3) Michael Kuhne, DB6NT, „12 GHz LO“, DUBUS Technik V, pp. 166-174

(4) Uwe Nitschke, DF9LN, „Oscillator for 2,5 GHz“, DUBUS 1/1998, Vol. 27, pp.42-52
(5) Charles Suckling, G6WDG, „Modern 10 GHz Transverter System“, DUBUS Technik
IV, pp. 332

(6) ROGERS Leiterplattenmaterial Firma Mauritz Hamburg, Datenblatt RO4003

(7) NEC, Datenblatt NE32584C

(8) MITSUBISHI, Datenbuch GaAs FET´s

(9) SIEMENS, Datenbuch RF-Halbleiter

(10) NEOSID, Datenbuch Helixfilter

(11) TOKO, Datenbuch Helixfilter

Source of supply:

Ready made units or kits:

KUHNE electronic GmbH,

Scheibenacker 3
D-95180 BERG
Tel.: 0049 (0) 9293 800 939
Fax: 0049 (0) 9293 800 938
Email: info@kuhne-electronic.de
Homepage: www.db6nt.com

All copyrights at the author DB 6 NT Michael Kuhne

For operating the high frequency modules the legal instructions have to be considered.
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 Precision crystal heater QH40A
This precision crystal heater provides temperature compensation for
crystals, usually found within crystal oscillators. The assembled
circuit, which is built on AL2O3 ceramic substrate, should be
mounted against the crystal using heat shrink tubing. The circuit
heats the crystal to a temperature of 40.8° C with an accuracy of
better than 0.1° C. This provides high frequency stability over the
temperature range of -5 to +40° C. This crystal heater is a reasonable
alternative to completely heated OCXO´s.
Reverse polarity of the supply voltage can lead to the destruction of
the circuit. Thin wires should be used for the connections to avoid
heat transfer and mechanical load. For operation in ambient
temperatures of 10° C or below, add some polystyrene insulation.

Specifications:
Adjustment tolerance: 40,8 °C +/- 1,5 °C
Regulation accuracy: better 0,1 °C
Operating voltage: 8...12 V
Inrush current: ca. 80 mA
Dimensions mm: 10,5 x 14,0 x 3,5

1. 2. 3.

1. The wires should be soldered to the pins provided. The S

shape of the wires (figure 1) reduces the mechanical load on
the heater plate (figure 3).
2. Warm the heat shrink tubing to hold the circuit next to the
crystal (figure 2), ensure that the temperature is not too high.
3. Installation of the crystal heater (figure 3)
Sicherheitshinweise – für Fertigmodule, Bausätze, Bauteile

Achtung: Verletzungsgefahr!

Weißblech / Neusilbergehäuse / Kühlkörper sind sehr scharfkantig. Bitte vorsichtig damit umgehen.
Darf nicht in die Hände von Kindern gelangen. Vorsicht bei Deckelmontage, Quetschungsgefahr der
Finger, Schnittgefahr.

Benutzung der Baugruppen, Montage der Bausätze darf nur durch autorisiertes Fachpersonal oder
lizenzierte Funkamateure erfolgen.

Bausätze / Fertigmodule enthalten Kleinteile, dürfen nicht in die Hände von Kindern und unbefugten
Personen gelangen. Verletzungsgefahr! Verschluckungsgefahr von Kleinteilen. Teile dürfen nicht in
den Mund genommen werden!

Elektronikbaugruppen dürfen nur innerhalb der Spezifikation betrieben werden. Maximale

Versorgungsspannung darf nicht überschritten werden!

Verpackungsmaterial (Plastiktüten, Styropor usw.), Kleinteile, dürfen nicht in die Hände von Kindern
gelangen. Erstickungsgefahr, Verschluckungsgefahr, kein Spielzeug!

Die Anleitung / das Messprotokoll bitte für späteren Gebrauch aufbewahren.

Entsorgen Sie die Module / Bauteile nur bei den vorhergesehenen Sammelstellen.

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Safety instructions – for readymade modules, kits, units

Caution: Risk of injury!

Tin plate / German Silver / cases / heat sink are very sharp-edged. Please handle with care. It should
not get into the hands of children. Be careful when assembling the top cover, danger of contusion and
cutting.

Using of the components and assembling the kits should only be done by authorized and qualified
personnel or licensed radio amateurs.

Kits / readymade modules contain small parts, and should not get into the hands of children or
unauthorized persons. Risk of injury! Danger of swallowing small parts. The parts should not be taken
into the mouth!

Electronic components are only to be run within the specifications. Maximum supply voltage should
not be exceeded!

Packing material (plastic bags, polystyrene etc.), small parts, should not get into the hands of children.
Danger of suffocation and swallowing – no toys!

Please keep the manual / measuring report for future use.

Please dispose the modules / components only at collection points which are designated for it.

Kuhne electronic GmbH - Scheibenacker 3 - D-95180 Berg - Tel. +9293-800 939 - Fax +9293-800 938