Sunday, September 11, 2005

Curious about Ham stuff?

Here is a homebrew 2 meter band Copper Colinear, I made from 1/4 inch copper tube for the aircon copper tube trunking. It took me about two hours to make this but getting the SWR optimum to 146Mhz is a little bit tricky!

Above are two photo of the M285 Diamond Antenna 5/8 wave for 2 meter band VHF for mobile. This antenna was giving problem with very high VSWR reading about 1:4 this means there was a loose joint or bad contact some where. If you notice I have to solder the centre base of the loading coil crimped to the centre pin of the antenna base insulation ring. The up portion of the tip of the antenna was also resoldered to make better contact joint. This result is perfect VSWR at the centre frequency at 144.500Mhz at VSWR 1:1.1 and the result was a prefectly repaired antenna suitable for usage back to the car.

Have you ever wondered what is the 2 meter band 5/8 wave MC101 inside look like? It seems to be made out of a stiff copper coil about 6 turns with a 1pf ceramic capacitor tapped at the base ground plane of the antenna and tapped at the top end of the loading matching coil.

Here is how a CP22E 2 meter band double stack 5/8 wave antenna looks like at 36 feet tall on my home QTH. The feedline is Diamond RG-8U 50 ohms with a circular loop just below the antenna act's as a balun to prevent reflected RF from the antenna from going back to the rig.




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    By Anonymous Anonymous, at 9:09 PM  

  • cA good project Rodney! Bravo to you! I still heat myself up on this antenna... on my head already planning to do it, but my time has not giving me any permission to go ahead! soon it will be my friend!

    By Anonymous Anonymous, at 12:21 PM  

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