The Variable Capacitor & Magnetic Loop Antenna Project - update 2 Sept 2010

After some tinkering.... I decided to use a single cable for both RF and DC... I planned to make use of the FT897D ability to tune the antenna instead of having a separate box just to tune the variable capacitor. Since the FT897D has a built-in circuit to control the YAESU ATAS screwdriver antenna, it should be able to do the same on this project.

I took some gears from an old CD player and a motor, coupled it with the motor controller that I made sometime ago for the Screwdriver Antenna project. I still need to make the Bias-T circuit before I can test the motorized capacitor. So far, with manual tuning, I can tune to 10m & 20m. I decided to abandon the wide-band loop project as I realized it require a much larger capacitance. It is very tricky to get a high maximum capacitance while having a lower minimum capacitance...

The Variable Capacitor & Magnetic Loop Antenna Project

I finally decided to start the project after being delayed for a long-long time... getting a 1mm aluminum sheet is not so easy as most of the seller only sells 4' x 8' size.
I used one of the drawing found on the internet and cut the sheets using my DIY CNC router that I build a few years ago..
The loop will be made from a aluminum bicycle rim for now. In the future, I am planning to use 30mm aluminum tubes but will settle with bicycle rim for now..At the moment, I have not measured the capacitance of the butterfly capacitor as I do not have the capacitance meter. Will leave that to 9M2CF I guess.. During testing with the new capacitor, I can tune to 10m but unable to reach 20m.. I need to increase the loop diameter and will do that when I decided to rebuild it with the 30mm tube later...

TM UNIFI??

The much awaited UNIFI Broadband service is finally here and I managed to get it installed early this month after it was made available at the place where I live.
Previously, I am using Streamyx 1Mb and I have to pay RM110/mth. Just by adding another RM40/mth, I get 5Mb, IPTV, 2Gb email and the best is... It uses Fiber Optic cable all the way into my room. That's mean, I don't have to worry about lightning strike coming through telephone line.
Now I wish the TNB power can be supplied using Fiber Optic too.. hahahaah

Cam Lock

Nothing much to say about this for now... mind is ticking and having sleepless night... sigh!!!!

Magnetic Loop Antenna

Last Sunday, I finally decided to use my free time to make something that I've always wanted to make... this time, without the the need of using the CNC machine...

The variable capacitors that I have in my previous tuner is taken out and the bicycle rim that I bought a few months ago is finally cut and drilled for M3 screws in order to attach the cable lugs.

The white PVC plumbing pipe that I bought about the same time with the bicycle rim is also put to use..

It took me about 1 hour and finally, I completed the 24" Magnetic Loop Antenna made from bicycle rim... I took it outside my backyard and tuned to 10m to get the highest pink noise level. Then, the moment of truth part 1... I set to 28.480Mhz and used a CW key to test.. meaning that, I set the transceiver to SSB and press the CW key to transmit a short tone... SWR reading is HIGH.. then, with a slight fine tuning by turning the capacitor, the SWR is now at a good level ( my transceiver does not have the numerical reading except by just displaying a bar, and its only at 1 or 2 bar) So, I guess it works...

Then I tried to tune to 40m... I can get a good pink noise level but I have no way to test the SWR as I my license does not permit me to do that... but I managed to listen to a radio broadcast on 9Mhz region at 5-9..

So, I will keep trying to catch some QSO on 28.480Mhz and will try to make a contact to get a signal report. That way I will know if my antenna works or not...

Here are the picture of the Magnetic Loop Antenna that I made:-