Fascinating looking at other setups around the world, i work with these every day for work. It’s not all the time you get to see other peoples work. Thanks for the video!
Love it when you post repeater information. I am fairly new to the hobby and my ultimate goal is to be be able to learn on how to work on repeaters. When you post these videos explaining this stuff just gets me so much more interested. My local club repeater trustee has been super exited to show me around as well, like to see other setups and maybe some day be the go to repeater guy because I just love them as well.
That's awesome to hear! I gradually taught myself with help from mentors and others too. A great resource is also the repeater builder website - www.repeater-builder.com/rbtip/index.html
I used to tune duplexers. I have found you can tune the plunger a little after you have set the reject capacitor to get better rejection without sacrificing pass characteristics.
Repeaters are very difficult to get to work well. Many repeaters suffer from desensing that often is not recognised. Also split antenna repeaters in combination with notch and or pass cavity filters are much easier to get to work if there is the vertical antenna height available. Amateurs often want a high gain single antenna combined with a duplexer. If it works then this is the way to go but often a split antenna using just 2 dipoles will produce better results, simply because it is much easier to achieve zero desensing. BTW it is possible to measure desensing remote from the site provided the signal from the testing site to the repeater is fairly strong. Another way is when keying the repeater if the tail varies in length when you let the PTT go then the repeater is likely to have desensing. Will VK6UU
Set and forget provided they don't get bumped or knocked about during transport. I usually set them up on the bench and then test again on site. I've had one set of older Motorola cavities that shifted over a bumpy 4WD track to the repeater site.
Gas discharge 'tubes' can cause their own headaches, and I found in 40 years, they are more trouble than worth, if proper grounding and bonding is tightly adhered to. Folded dipoles are 'quieter' than colinear and corporate feed antennas by their design. Look at large commercial antennas, the metal cap is directly connected to the internal ground path, with the elements attached at the low impedance point, which allows lightning/electrical discharges to route directly to ground, and if ground straps are installed in the shield of the cables, along the length down a tower leg, that greatly increases the losses of the impulse to be shunted to ground, and not into the equipment. I work on sites that are at 5,000 + feet in elevation, often above 8,000 feet above average terrain, also with heavy snow loads, so you do your best to ensure you do NOT have to make your way back up and fight the cold and deep snow just to repair a minor failure.
BANDPASS, BAND REJECT, PASS, REJECT, NOTCH...DIFFERENT CAVITIES FOR DIFFERENT REQUIREMENTS. NOT UNUSUAL TO HAVE MORE THAN TWO CAVITIES FOR OTHER SERVICES TO BE PART OF THE MAIN REPEATER, TO NOTCH OUT SUM AND DIFFERENCE FREQUENCIES, AS WELL AS NEARBY HIGH LEVEL SIGNALS FAR OUTSIDE THE PASSBAND OF THE INTENDED INSTALLATION. NOTCH CAVITIES ARE GREAT FOR THIS PURPOSE.
