OK1DFC – 8m offset DISH project

Year 2022


Hub               Mirror






Feed holder            Feeds




In March 2022 I finished all the details and adjusted the dish focus together with the antenna feed for the 1296 MHz band. The final result after adjustment is 21.5dB Sun noise at 120 SFU and 0.9dB Moon noise with clear sky and 33% relative humidity


Year 2021



Today 17/10/2021 I made the first experiment with listening in 1296 MHz band. The dish was so far only manually controlled in AZ and EL. The feed was a feedhorn used in a small offset antenna with F/D 0,6. However, for this new antenna I need an feedhorn with F/D 0,457. Nevertheless, I used the Q65-60C mode to decode the SM5DGX +1DB station and listened to its signal on a 59++ loud speaker. All that remains is to finish installing all the coaxial cables, control cables and get the auto control working, and do a final calibration to the Sun noise. However, the first attempt went well.

15th of October

Today I brought the last mechanical parts for the final assembly of the feed holder. This afternoon I assembled everything and installed the mount into the antenna. All the major work on the mechanical parts is complete. During the weekend I will try to test the sun noise in the 1296 MHz band with the existing feed, which is designed for a dish with F/D 0.6. For the final form of the feed I need to make a new W2IMU collar, so that my new offset dish with F/D 0,457 will be properly illuminated. I am making collars for 1296 and 2320 MHz.

23rd of September


13th of October

I put the parts for the feed holder assembly into production today. After performing a static calculation for bending, I chose 50mm diameter duralumin tubes with a wall thickness of 2mm as the main supporting element. Two 50mm diameter tubes will still provide longitudinal stability.



21st - 26th of September

Today the mesh finally arrived from the supplier and I was able to install the first 12 mesh panels on the dish. Weather permitting, I would like to complete the installation of the mesh by September 26th. I've finished all the work on the offset dish mirror. All parts of the mesh are carefully attached to the center and edge of the dish, as well as attached to the arms with stainless steel screws.



10th - 16th of September

Today I finished installing all the ribs in the dish. However, the rain drove me away from finishing the installation of the last four ribs to the outer ring. The mesh for the dish filler should arrive on Tuesday next week. Weather permitting, I'll finish all the details over the weekend and start coating the dish with mesh next week. I still have to make the self-supporting feed holder.



1st -7th of September

I dedicated the first and second week of September to the production of 36 extension ribs. The aluminum material arrived slightly late, but I managed to finish all 36 pieces by 10.9. I also did a test install of the first 9 ribs during the weekend. Everything appears normal so I will be able to complete the basic installation once the outer ring material is delivered. In the next few days I have to install the mesh and the feedhorn holder.



2nd half of August 2021

On the evening of 31 August, a crane arrived and helped lift the 4m diameter central section onto the mast. All the connection points are connected and the dish is sitting on the balancing boom. At the end of the installation, a 300kg counterweight was placed on the balancing boom. In the next few days I have to install the feed carrier and manufacture 36 pieces of extension arms. I hope to have everything done by the end of September 2021.



Extension ribs



1st half of August 2021

4m central part of dish

Final assembly and mesh



July 2021



The time after Covid19 brought a significant increase in material and labor costs. Therefore, due to the increase of the financial budget by 100%, I switched to the production of dish arms by welding at home.



April 2021

Control unit - AZ/EL

consists of an OE5JFL control module modified by ON4BCB. Walter modified the Hannes module so that engines up to 24V/10A DC could be controlled.



January 2021

Weather still do not allow to work outside. Picture from the 5th of April 2021

During the winter, the entire surface area of the dish has been finished by design. Production of parts of the arms on the laser machine is underway, as well as the manufacture of the feedhorn carrier. Unfortunately, the COVID19 pandemic has also hit production capacity and so production has been delayed from September 2020. I hope that within the month of April, everything will have been produced and final assembly can begin. I also managed to get a great mesh made of anti-corrosive material with a size 6x6mm and a wire strength of 0.8mm.






Building of dish is postponed due to COVID19 travel and works restrictions until April 2021


Year 2020

September 2020


After weighing all the pros and cons of making ribs, I have opted for laser cutting technology to ensure the absolute geometric precision of the parabolic curve. Using bending and welding technology, the area of the parabolic curve deforms, reducing the efficiency of the antenna.




August 2020


Balancing boom


The balance beam is finished and mounted on the mast. The azimuth and elevation gear is tested. Position sensors will still be installed in April 2021


Central HUB


after the shoulder width change, the final length of the central tube will still be adjusted. After the modifications, the final incandescent zinging will be performed.




July 2020

Start with design of ribs. On the right is visible model of whole dish and cut in axe X and Y. I decide to made ribs on laser cutting machine. Same design as I have for my prime focus dish 3,2 and 4,8m




Axe X = 7825mm

Axe Y = 8248mm

Deep of whole ellipsoid  = 1100mm

Deep of internal ellipsoid = 270mm

F/D = 0,457

Offset angle = 18,45°


18 PCs of main ribs

18 PCs of supporting ribs


Dimensions as .pdf file Czech


Dimensions as .pdf file English


A big thanks goes to Hannes OE5JFL, who provided me with big help and all the information that led to the design and design of my dish mirror.


Thank you very much Hannes !!!


Dish 3D surface

Axe X

Axe Y

June 2020


Building frame for dish, hub and elevation. In the construction of the balancing boom, I adhered to the proven design of the 10m parabolic antenna used previously. The design is designed to meet wind load conditions up to 130 km/h. I hope that the antenna will be able to withstand such a load as the previous dish during the Kirill orca in 2007, when the wind gust was 146km/h. Drawing details.




May 2020

Possible to work outside again.

Trenching, installing power cables 380V and pipes between mast and container. Fiber optic cable for communication in house and container. Many other small works, almost not visible but very important for new dish.



April 2020


Finishing new control system which consist from F1EHN and OE5JFL - ON4BCB for SE14 and SE12 solar gears.



March 2020

New box for elevation install on azimuth gear



Jan-Feb 2020


Building new control system for 2,6m offset with F1EHN, resolution 0,01° for AZ and EL, used US digital encoders. Second part is for 8m offset with OE5JFL and MAB25, resolution 0,1° for AZ and EL.



Year 2019

December 2019

New box for elevation install on azimuth gear. On right side 12" gear for elevation, on left bearing for elevation.

Control system for 8m dish consist of OE5JFL with ON4BCB upgrade for 24V/15A regulation, with 0,1° in AZ and EL accuracy. Same box will include also F1EHN with US Digital encoder for control of 2,6m dish with accuracy 0,01°in EL and AZ.




November 2019

Works on dish design. Dish will have dimensions 8,25m long, 7,9m short, F/D = 0,457, 36ribs. Expecting to use white steel mesh 6x6mm and 0,8mm diameter of wire. First draft of design.



October 2019

I have finish first part of mast, which is made from 600mm diameter steel pipe 3800mm long.



July 2019

July 2019 I have removed my previous PF 10m dish and build new system consist with 2,4m offset and 8m offset dish. 2,4m will be use for 5,6 - 10 - 24 - 47 GHz and 8m will be use for 432 - 1296 - 2320 - 3400 MHz. Some information about build of new system I will put here on page of 8m offset dish.