Amateur radio station since 1993

My transverter 144/28 with high dynamic range




























































































Receiver dynamic range is the ability of a receiver to receive a weak signal without loss of
readability while a strong signal is present.

I see at 2004 years Javornic 144/14 design by S53WW and designed my XVTR.

In my QTH was very high level QRM. Also on 144 MHz in Ham contest amateurs typically produce
power levels of 10- 15 kW ERP
with 1kW RF into a 10-15dBd antenna. The received powers -10 dbm to + 10dbm at some
different distances of free space propagation.

Transverter with high THREE-SIGNAL DYNAMIC RANGE :

- Local oscillator (with temperature-compensated) 116 MHz. Phase noise LO is better -150 dBc/Hz at shift of 10 kHz and better -145 dBc/Hz at shift of 1 kHz ! LO for all my XVTR (144,432,1296,6cm and 3 cm) by UA3AOH !

- High IP3 Level frequency mixer SYM-18H (Mini-Circuits, LO +17dbm)

- High IP3 level in the receiver low noise stage with 2xBF981 and BFG591

High selectivity with 4-stage helical band pass filter (from FM-301 Hungary FM stations) - more 70 db rejections outband 144-146 MHz. Also final low pass filter rejection spurious and harmonic of more than 60 db (filter LPF also from FM-301 with modifications).

Main circuits :

You can DOWNLOAD PRO Version and Light Version circuits,
protection for XVTR 144/28 in detail

Different betwen PRO Version and Light Version - in "Pro" use second unit for only TX-stage : second filter , TX stage and second high level mixer. In "Light" single filter and mixer use for RX and TX.

The TX power of the transverter can be adjusted with the potentiometer on the front panel - aadjusted high level balanced stage 2xBF961(981) .

PA: use RA13H1317M about output 20 W , Circuits level control : 2...20W

Precision generator 5 MHz , calibrator frequency 145500, 1 ppm stable in 4 years period

Filter - 4-stage helical band pass filter for TX and also filter for RX circuit
. Sequencer circuits with remote control coaxial rele.

The output power, input IF power and SWR is indicated on a meter in front panel.


Modifications in 2011 :

- new design TCXO for LO unit

- new 1 stage with high reliability GaAs MESFET FH1-G

NF of new front-end ( FH1G in 1 stage)


You can see fabrication stages similar to mine XVTR for RA4SD

PA module RA13H1317M - power out 30W


The sequencer is inside :
Delay of giving of power from IF 28 MHz
Delay of inclusion PTT for TRX and PA

Input and output of 144 MHz are separate !