The VFA3D is based on the M0MCX concept for a vertical multi-band antenna with radiator for the corresponding amateur radio bands. Once tuned, the antenna does not require an antenna tuner and thus enables a quick band change.
What makes the VFA3D stand out is the integrated clamping device with which the plates and clamping rings hold their position on the pole and the use of rubber C-profiles to distribute the pressure better to the fiberglass pole. There is therefore no need for cable ties or similar to hold the plates in place. I first saw the clamping ring concept on the Ice Cone antenna from DO0PAT.
The VFA3D also uses 4mm banana sockets and plugs for quick assembly and disassembly. This eliminates the need to screw on eyelets or fork contacts.
As I don’t have the space to permanently install an antenna, the VFA3D is optimised for portable operation. The aim was to reduce the number of components to a minimum and to use as few special parts as possible. Apart from the 12m spider beam mast, the DX10 antenna wire and some screws, nuts and plugs, everything can be produced using 3D printing.
I am currently using PETG filament, which offers better temperature and UV resistance than PLA. PETG does not pose any major challenges for 3D printing and is therefore just as easy to print as PLA filament.
3D printed parts
# BP – Base Plate (1x) # RR – Radiator Plate (1x) # GP1 – Guy Plate (1x) # SPM – Spreader Plate (1x) # GP2 – Guy Plate(1x) # TOP (1x) # Clamp Ring (6x) # Loop Maker (6x) # Elastic Cord Stopper (6x)
Remaining components
# Spiderbeam 12m # Antenna wire # Elastic band # M5 square nuts # M5 cylinder head screws # Aluminium flat profile 11×2 mm # Rubber C-profile # 4 mm banana sockets # 4 mm banana plugs # SO-239 socket with M3 screws and nuts # Shrink tubing with hot melt adhesive
The individual elements of the GFA mast are secured with 3D printed clamping rings. The clamping rings always sit on the lower transition. The advantage of using the clamping rings is that the GFA elements only need to be lightly clamped together, which simplifies dismantling.
Top view
Bottom view
The opening for inserting the M5 square nut can be sealed with PETG material and a soldering iron to prevent the nut from falling out.
The black ring is the plastic C-profile, which ensures a more even distribution of force.
Note: The clamping ring should only be tightened so firmly that it can no longer be moved. Otherwise there is a risk of damaging the GRP pipe.
Base plate printed from PETG filament equipped with 8 pcs. of 4 mm banana jacks and one SO-239 socket. The radials are connected via 4 mm banana plugs. The use of banana plugs allows for quick assembly.
The radial wires and the outer conductor of the SO-239 socket are connected to each other with a strip of 11×2 mm aluminium.
The base plate is attached to the GRP mast via an integrated clamping ring. A rubber C-profile is used to protect the GFA mast.The clamping mechanism consists of an M5 square nut and an M5x16 cylinder head screw.
Base plate with attached 4 mm banana plug
The 4 mm banana plug has the advantage over the fork contact that it can be simply plugged in.
Radialset
The 4 mm banana plug used can accommodate up to four radial wires. The radial wires are soldered to the banana plug and protected against the ingress of moisture with a shrink sleeve.
Reproduction is at your own risk. I accept no liability for the correctness of the information or damage that may occur.
Background information
During my project pihlSDR-Enclosure I encountered the problem that my Raspberry Pi5 sporadically switched itself off. After a few attempts and research, I realised that it was an undervoltage problem. I had set the power supply to 5.1 volts, but this did not reach the Raspberry Pi5. Under load, the voltage then dropped below the critical value, which led to the shutdown. The method described below was the solution for me. Since then, the undervoltage error has no longer occurred.
Start the first connection with Putty and enter the command stress --cpu 4.This performs a stress test and generates approx. 2.4 amps of power consumption. Note: You can quit the command any time with Cntrl + C.
Start the second connection with Putty and start the command watch -n 1 vcgencmd pmic_read_adc EXT5V_Vin the CLI. The actual supply voltage at the Raspberry Pi5 is now displayed.Note: You can quit the command any time with Cntrl + C.
Now set the voltage on the buck converter so that the voltage output in the CLI is 5.1 volts under load. Please note: Carry out the setting slowly and carefully. If the voltage is set higher than 5.1 volts, the Raspberry Pi5 and the devices connected to it may be damaged.
Now the undervoltage problem should no longer occur.
Reproduction is at your own risk. I accept no liability for the correctness of the information. This documentation is not a complete set of assembly instructions. Rather, it is intended to stimulate your own creativity for your own concept.
VY73 DL1EGL
The Waveshare 10.1-inch PCAP touch display is used in this design. The dimensions of the housing were chosen so that a Hermes Lite 2 pcb with N2ADR filter board pcb and the ATU-100-EXT pcb can be installed. The controls and display of the ATU-100-EXT were positioned on the right-hand side of the housing. Apart from an on/off switch on the rear of the housing, no other controls are provided. It is operated solely via the touch display or via a USB keyboard/mouse combo.
The handles integrated into the side panels also serve as protection for the touch display.
Dimensions and Weight
Width … 285 mm Height … 168 mm (*) Depth … 200 mm Weight … 2450 gramm
(*) without feets
Connectors
The following connections are located on the rear:
Backside
2x USB-3 (connected to the Raspberry Pi5) 1x USB-2 (connected to the Raspberry Pi5) 1x HDMI-2 (connected to the Raspberry Pi5)
1x SO-239 TRX (connected to the Hermes Lite) 1x SO-239 ATU (connected to ATU-100-EXT) 1x SO-239 ANT (connected to ATU-100-EXT)
Note on the SO-239 sockets:
If no external PA is used, the TRX and ATU are bridged externally with an RG58 cable. To use an external PA, TRX is connected to the input of the PA and the output of the PA is connected to ATU. With this solution, the ATU-100-EXT can be used in both cases.
1x 12V DC (for external power supply)
1x 3.5 mm jack stereo (K . … currently not yet in use) 1x 3.5 mm jack stereo (C … currently not yet in use) 1x 3.5 mm jack stereo (S … currently not yet in use)
View with open lid.
SDR Software für Raspberry Pi5
Either piHPSDR or deskHPSDR is recommended as touch-compatible SDR software to be used with the Hermes Lite 2.
3D print files
The print files will be available for download here shortly, as soon as the final work on the design has been completed.
3D Printing informations
Total printing time for all 3D printed parts … 40 hours Filament quantity for all 3D printed parts … 885 gram Filament … Sunlu PETG grey Wall loops … 3 Infill density … 25%
The speaker header should not be used, as this leads to interference in the reception spectrum via the loudspeaker lines. The 3.5 mm audio-jack is better suited for connecting external loudspeakers with an appropriate amplifier. Note: The Raspberry PI5 itself no longer has a headphone or loudspeaker output.
The Waveshare 10.1 PCAP touch display should be supplied directly via a USB-C 5V cable.
I have changed the DC DC converter from Hailege H-1-154 to BGTXINGI. The BGTXINGI produces less HF interference and has the advantage that the output voltage can be variably adjusted.
I have also integrated DC filter boards from YOUMILE.
If you know HF-clean 5V DC/DC converter that can deliver 5A, then please send me a E-Mail :-).
An analogue voltage converter is unfortunately not an option due to the considerable heat development.
