G3VPX HF Transceiver - photographs

Photos taken on Canon EOS10D or Canon G9. Double click photo for full 5 megapixel original

Front view

Front panel - MDF on hardwood surround - made by mycabinet-maker friend. This one's been chopped around and damaged during 18 months development. I have two spare - one is being cut at present and will be installed and then properly labelled.

Switches: T/R   Fwd/Rev/ALC   AGC-hang/slow/fast   Pre-amp   Band-up/down   Fast-up/down   Step-10/50/100Hz

Bottom controls:  AF gain    RF gain     LSB/USB/SSB/CW/RTTY     Rx bandwidth -2.4kHz/2.0kHz/500Hz

Right controls:  RIT (+ switch & LED)   IF shift     spare x2 (DSP?)   Vox delay/off   Vox gain   Tx drive    Mic gain

Key pad:  A and B forA/B VFO switching. (LED indicators under A and B buttons

                C copies A to B      Numeric freq entry (auto band switching)     Fn nnn - setup functions


Front panel left controls


Front panel right controls


Top and front view. Note LCD panel which was included for PIC chip development/diagnostic puposes


Rear view - 20watt and 120watt PA units


Three layer construction - top layer elevated for access to middle layer.

(note heat sink nut under top panel for 1st LO DDS.  Bolt head ground square to contact underside metal heat pad of AD9854ASQ)


Top view - bottom right 100w bipolar PA, top left:, 1st LO DDS and BPFs, top right:, PIC digital


Middle layer - left: 9 x 4 pole rf filters     right: Rx IF and audio amp

Centre:    Top - 45MHz IF   bottom left AGC,      centre right 8.67MHz osc.      bottom right - Tx BPF ouput amp


Middle layer with screening of Rf filter, 45Mhz iF and 8.215Mhx/455kHx Rx IF boards.


Bottom view - left: transmit IF, top-right: ALC, middle-right: CIO DDS, bottom-right: power control


- with TI DSP board fitted. ( TMS320VC5416 DSK)
DSP not operational - Still working on major brain upload here !!
CIO and Tx IF screened
Attenuator and filter unit fitted in RF drive path after driver amp - see below

Filter unit un RF drive path between driver amp and 20w PA
- 8.67Mhz notch filter to reduce 2nd LO signal
- 1.5Mhz Cauer HPF to remove LF spurii


PIC controlled attenuator in RF drive path: 0 2 4 6 8 10 12 and 14 dB (three pi-attenuators of 2, 4 and 8 dB)
Allows drive to be preset per band
Reduces unwanted gain on 1.9 3.7 and 7 Mhz which was causing a strange instability when the power exceeded 60w or so.
(a whole series of sidebands spaced at 320kHz)


TI DPS boad close up. USB connection to PC bottom left. Signal connections top. ( 20kHz stereo in and out)


MDF/hardwood front panel removed


Meter & digital display detail - note tiny bulbs within meter case


Rear of MDF/hardwood front panel. Made by a cabinet maker friend. I have two spare - this one's been hacked about!


Underside front panel details. Note the Agilent rotary encoder for main tuning control (eBAY!!)


PIC microprocessor board. Note the 5/3.3 votage level changing resistors to drive the (parallel interfaced) DDS chips.

Uses 8Mhz osc + internal PLL quarupler to run at 32Mhz.   Socket for in-situ programming on left.


Underside of PIC board. Power supplies in copper. Wiring is R S Components wirewrap wire


Pic baord wiring - closeup. Believe it or not this has been very reliable.

Wire wrap insulation doesn't melt easily so you can run the insulation right up to the solder.



8 bit to 24 bit breakout board for more digital outputs from PIC controller


Local oscillator board. left top: clock 200Mhz     left bottom: DDS and parallel digital control     right 5 BPFs


DDS and clock close up.

Oscillator is Pletronics 200Mhz low phase noise with LVDS output

Uses DS90LV018A   3v LVDS to CMOS differential line receiver chip


Cauer 7-pole BPF in LO output (76Mhz bandwith ... .max LO freq. is 45 + 29.7 = 74.7 Mhz)


DDS baord before mounting chip. Hole for heatsink (and for the blue-tack to hold it while soldering!)

This did not have separation of Analog and digital Vdd and ground lines. (The later CIO board did)



AD9854 455 kHz CIO and output filter and buffer amps. (3.3v SMD regulators underside left)

Murata 455Khz 35kHz wide filter from JABDOG   + 50ohm matching transformers

(Need wide filter when switched to440Khz or 470kHz to produce 15kHz 4th IF for DSP unit)


Underside of CIO DDS board. 3.3v regulators on left. Separate analogoe and digital Vdd wiring in red. Split ground.


Colpitts 8.67MHz Xtal osc + separte receieve and tansmit buffers.

NB: Transceiver SSB filters at 455kHz and 8.125MHz - so this osc will give 'unwanted passband tuning' if off frequency!!


Underside of 8.67MHz osc - note three surface mount BFP183 rf transistors


Rx IF board top. 45Mhz in - 8.215MHz IF (AD603 amp),   455kHz amp (AD603 x 2).

Bottom centre: 8.215MHz filter PIN diode switchimg control (Darlington x 7 chip).     

 Bottom right - 53.215 MHz oscillator.     (Sawn off left corner was previously audio amp and 8.67Mhz oscillator!!)


Rx IF underside,. Left to right:  AD831 demod, AD603 amps x2, AD831 8.215M-455k mixer, AD603 8.215Mhz amp, ADE-1 mixer

Yellow wire is AGC. The 8.215MHz AD603 amp has a (trimpot adjustable) offset gain control reference so that progressive

AGC gain reduction reduces 455kHz gain first.

Double click to magnify - note bottom right - BAR04-06 surface mounted twin PIN diodes for signal switching (3 filters and Tx IF in)


Audio AMP - TDA2040 ( designed for 40v operation - but produces 4watts into 4ohms at 13.8v)


Rx IF board (45Mhz in, audio out). 53.215MHz osc top left. Audio power amp top right.

Note power and control line filtering unit at top of photo


Tx IF top view. Audio in,  8.215Mhz out.

Note carrier bypass coax   - PIN diode switched  - two series and one shunt to earth - so many switching components!


TX IF bottom view      AD831 bal mod on left and AD831 455kHz - 8.215MHz mixer on right


AD831 Balanced modulator closeup. Chip caps are 1000nf


Two twin op amps - microphone input and Vox


Analog devices SSM2167 mic. amp (compression etc - used in cellphones)


Tx IF - AD603 8.215 Mhz amplifier


45MHz IF board. note 20kHz 4 pole crystal filters (two on receive, one on transmit)

BF996S surface mounted MOSFETs and ADE-1 first mixer are on board underside

Relays on right to switch MAX2611 RF pre-amp.


Underside of 45Mhz IF board - ADE-1 first mixer (Rx and TX) top right

Surface mount semiconductors are Rx and TX BF996S mosfets, MAX2611 rf preamp

and BAR64-06 twin PIN diodes for R/T switching.


PIN diode switched RF filter board. Nine four pole Chebychev filters.

The chips are 74HC138 3 to 8 decoder and two Darlington x7 chips.


Underside of RF filter board


AGC board. 455MHz input. Hang/slow/fast - relay switched     plus S-Meter transmit receive relay.


Underside of AGC board



ALC board. RF drive, SWR - reverse and forward metering and output limiting

DIL relays switching meter between ALC and reverse and forward power

Bottom left is a simple 5 bit DAC used to set 45MHz transmit gain (level is entered by keypad and stored for current band)


Bipolar 120w PA - using G6ALU's board design . Uses a matched pair of 2SC2879 transistors.


G6ALU PA and LPF unit - top view


Tx output LPFs x6 - relay switched controlled by PIC chip. SWR meter and T/R relay on right


Underside of LPF board


Power distribution in a shallow compartment under PA and LPF compartment.

Shottky diodes protect against reverse polarity. PA protected by 40A automotive relay