T match the start
First when designing any sort of tuning unit you need to source parts, this can be easy if you just spend lots of money on the project, this I feel spoils the fun and challenge a little.
I asked around the Radio club if anyone could help with parts, as it happen Andy G7LRR who has been collecting variable caps for years had a nice per of EX BBC transmitting Capacitors rated at 65pf 350pf @ 10kv each.
Being able to get hold of old electrical enclosure to mount the Components was just the sort of thing I needed.
Next was making a roller inductor which from all odds and ends in my workshop, a nice fibre glass former and heavy-duty wire was found , the Rollers I made on my lathe , great job and it works really well.
Then all the components were then mounted in the enclosure to make the T match .
I found that on the load capacitor had to remove some of the plates in order to reduce the lower value to around 10pf his helps when using a long wire.
Next job was how to make this work remotely from the comfort of my radio shack.
After weeks of reading and planning I came across this article in Radcom March 2014 by Andy Talbot G4JNT using servo motors on the Tune and Load capacitors and an old motor wind screen motor on the roller inductor. also with a little help from Hirek M0HDD/SP6ML
The design involved using 2 x ne555 timers to servo motors .
I made the control unit and am very pleased with how it works .
Since then the unit is installed and has worked with very good results.
This project was not really hard to make but took a long time in planning and many hours in the workshop to build.
Please enjoy my short video of the tuner working and the pictures of the tuner and control unit
Marcin M0GLV /SP4BHD