Modification of my Hygain HAM4 rotor

I was interested by the automatic control of the rotor by a PIC or an Arduino after my surf of the web or in a magazine,

I found that K3NG Anthony represents the complete source for the ham who have some electronic and informatic acknowledgements and like the DIY.

https://groups.io/g/radioartisan/topics

I looked for the informations and examples for the HAM4 Rotor and found that in the messages files that there is a big problem with that sort of rotor and the connection of it’s potentiometer Wiper to the chassis of the rotor (so to the earth) and the presence of 50hz hum returning from that potentiometer.

I took some informations from OK1HRA Dan site and made a circuit in order to command my HAM4 by a pc and with help of  Dan & Anthony i made my project to talk with my Logger32 but hum and bad calibration made me to look for another solution.

http://ok1hra.nagano.cz/

I don’t know why even all the solutions for that hum and floating of the potentiometer, none worked for me.

I found that VK5DJ found the solution by insulating the potentiometer’s wiper from the chassis of the rotor.

That is the solution I followed by founding a large piece of Teflon from a Tube power amplifier.

VK5DJ don’t give any measurements for the insulator so I have to discover its from the pictures and what I have in hands.

https://www.vk5dj.com/potentiometer.html

I opened the 4 screws of the HAM4 Rotor. The balls have had some oxidation marks but still work for a while.

I dissembled the large potentiometer retained by 2 screws from the rotor and start the modification by removing the wiper made (a piece of copper) from the potentiometer which is retained by a small clip.

I made the copper to be a flat piece then i made 2 traces on the copper 19mm apart and 2,5mm from the 2 points of the copper then I drilled 2 holes of 3mm.

The 2,5mm is the distance where the copper is bend little bit to enter in the notch made on the dome of the rotor.

HAM4 Potentiometer Wiper

The wiper is now ready to accept the piece of the Teflon insulator that measures 31x7x7mm.

 Here is the measurement that I made for the insulatorthat I made using a saw, a lime and a 22mm diameter small saw.

This is my 1^st drew using the LibreOffice Draw, so be compliant.

HAM4 Insulator

Then with 2 screws of 2,5mm diameter I fixed the insulator to the copper piece of the wiper.

I tried mechanically that isolated potentiometer in the dome notch which seems ok.

The copper piece should return to its place with avoid to connect the wiper to the chassis. Hygain made a place for a flat 6 faces (6mmlarge) screw that is originally unused but is appropriate for me.

To complete the modification I have to release a connection for the wiper from the 8 terminals in the bottom of the rotor.

Insulator & Capacitor installed

The solution found in the web is to reinstall the 120uF capacitor from the Hygain command box to inside the rotor. The capacitor is soldered in parallel to rotor solenoids. So I have terminal No 4 & 8 frees. I soldered the wiper cable to the terminal No8 and leaved No 4 unused.

In the Hygain command box I made the connection from terminal No 8 to the wiper of the 5k potentiometer in the S2 switch and remove the connection to the earth.

I don’t touch to the terminals No 3 & 7.

HAM4 Modified

I made also the Brake Delay to protect my rotor which consist to add 2 diodes, a chemical capacitor, a resistor and a 24v relay to make a delay to release the brake motor.

Please check the web for the informations about the break delay otherwise send me a message to get a copy that i found in the web.I am NOT the author that i thanks for his schematic.


Later and better i found in the web a solution to the Brake Delay of the Hygain rotors.
The circuit was made by the DL0WW Radio Club that I thanks for its free schematic.
It will need also some modifications to make in the Hygain control box but the result is wonderful.

https://www.dl0ww.de/pix/download/RotorBremsverzoegerung/Rotor_Brake_Delay.pdf

Now and finally i can say that my Hygain is a complete Rotor.

My email is : cn8li  yahoo  fr