70cm transverter

By G4DDK

EME2018

Iceni

Contents

• Introduction to the Iceni

• Design of the transverter • Device update

• Analysis • receiver,

• Transmitter

• Local oscillator

• Frequency locking

• Summary

Iceni -A 70cm transverter design for the home constructor

Iceni (I-see-nee) • An ancient Celtic tribe who

inhabited the east of England 2000 years ago.

• Their queen, Boudica, famously drove the Romans out of Colchester and London, before suing for peace (was this the first attempt at Brexit?)

Iceni design

The schematic block diagram of the Iceni will be familiar as that of a conventional single conversion Up/down converter.

Mixer Filter

Transmit Amplifier

RF Amplifier

LO Multiplier 101MHz Xtal oscillator

IF Post mixer Amplifier & BPF

Input attenuator

28MHz

28MHz

101MHz

432MHz

432MHz

Control/ interface

Device update

Due to Broadcom acquisition of Avago, certain devices are no longer available

However, thanks to MiniCircuit Inc.

• PGA105+ replaces the MGA30689

Last year, after input from SM5BSZ, the

• PSA4-5043 replaces the SPF5043

And as a further Broadcom/Avago update, the SAV540+ now replaces the ATF54143 in the VLNA preamps with proven equally good results.

Device update 2

The level 13 ADE-751MH is now offered as a replacement for the (nearly pin-compatible) level 7 ADE-13

ADE-751MH Modification

Easily modified existing V1.0 PCBs

AppCAD analysis of receiver - ADE13

ADE751 mixer upgrade

Iceni noise figure and gain

Measurement of dynamic range

G R&S SMG

MI2024

ZFRSC-42

ICENI

HP8592L

432.180MHz

432.200MHz

Calibrate 28.190MHz CF

-40dBm/tone

-16dBm/tone

Texscan

With ADE13

Measurement of Rx dynamic range 2

ADE751MH Mixer

Transmit analysis – ADE751MH

LO

Mixer Diplexer Diode switch

BPF Attenuator 432MHz BPF Diode switch

Tx amplifier 432MHz BPF Tx amplifier Low PF

Transmit chain ADE751MH

28MHz 432MHz

404MHz

0dBm -3dBm -10dBm -15dBm +9dBm +4dBm +17dBm

+13dBm

Toko 1072A helical filters

Available from RF Microwave (Frank Rota)

Transmit analysis 2

Spectrum from 10MHz to 1510MHz 0dBm IF carrier drive

K3 2-tone drive at 50mW PEP output 3rd order -40dBc/tone

Local oscillator analysis

101MHz Butler oscillator (SM5BSZ) x 4 = 404MHz

Local oscillator amplifier LPF and BPF

-145dBc/Hz@404MHz -144dBc/Hz

+12 / +13dBm at 404MHz

10kHz separation

Local oscillator injection locking

Iceni External 101MHz source

External LO input

Checking phase of the two LOs

G

R&S SMG

MI2024

ZFRSC-42

ICENI #1

101MHz

432.200MHz

28.200MHz

ICENI #2

Extl LO

Extl LO

RF in

RF in

Ch 1 Ch 2

Dual channel 60MHz scope

ZFRSC-42

Diversity arrangement

404MHz 432MHz

Locked dual oscillators

Summary of performance and kits Designed as a low cost but good performance 70cm transverter with 10m IF

Readily upgradeable for power output using the G4BAO driver or Mitsubishi PA module

Can be frequency locked with simple injection locking

Two can be used for dual polarity diversity reception using common injection locking

PGA432 preamplifier can be used with the Iceni to improve sensitivity

At present full kits are available. With the exception of the PCB all parts are readily available from a number of sources

Construction is fully documented at G4DDK.COM