Update 4/24/17

 Hello all,
Saturdays trip went well and the list of tasks were completed. I went up to complete installation of the “control receiver” and to analyze all the antennas with more knowledge of the tools I was using.
First I finished the control receiver install.  It took a little bit to get the controller programming correct to know when the receiver was active.  Then after that had some audio issues and adjustment.  With the receiver being adjustable on its audio output the controllers audio input and output adjustable its a little tedious getting things just right.  All is connected and working at this time.  Also removed the Icom mobile radio that Bill had been letting the repeater use and will be returning it to him.
Next was to analyze or “sweep” the antennas. (see pictures here) I went threw all the antennas and did this with a Bird SiteHawk and Anritsu S311D Sitemaster.  They both are very accurate TDR (Time domain reflectometer) that will both show you if and were a antenna is resonate and also how long a feed line is or the DTF (Distance to Fault).  When testing for antenna they sweep a frequency range that you set.  In our case we have VHF and UHF systems and I swept different areas for the different antennas.  In the Pictures you can see on the bottom in the left corner a start frequency and the right corner a stop frequency.   At the top of the picture you will see what kind of test it is (Return loss or Distance to fault).  On the Return loss pictures the vertical scale is what signal level in DB that is not leaving the antenna or is getting reflected back.  The horizontal scale is the frequency.  A feed line and antenna that is in good shape should be at -14 or lower, -14DB is about a 1.5 SWR.  So as you can see we have some issues on some of the antennas.
The DTF pictures are a used to find bad connectors, damage in a feed line and a very precise measurement of a feed line if it is unknown. The test equipment lets you choose what kind of feedline you are using and takes into account the los of the cable on your frequency, velocity factors, ext. On the picture for the “Southlink you can see the line is pretty flat till about 20 feet then there are two bumps, that is the length from the jumper from the cabinets to the polyphaser.  The first bump is the connector and second is the Polyphaser.  The large spike is the antenna and the complete length of the antenna system. Some of the DTF pictures you can see where the main hard lines stop and then go to a short jumper to the antenna by the small bump befor the large spike of the antenna.
The “mainsouth” picture shows a flat line or completely dead antenna system, not a good thing. The northmain there are two pictures that show how the wind was “changing” the resonance of the system, that indicates that there is probably a mechanical problem (bad connector or damaged feed line-antenna).  The “backup repeater” return loss picture shows what a antenna in good condition looks like.   The “V” on the graph is clean, smooth and on frequency.  It is a very precise Ham band antenna and not a broad band commercial type antenna but gives a good idea of what its suppose to look like.
The North, South and Echolink link antennas are Log Periodic Yagi antennas and look different then a Omni vertical because they are designed for a very large band of frequencies.   The Echolink is the best example of what they should look like.  Each dip is the different elements on the yagi and what frequency it is resonate at.
The APRS and Control Receiver antennas are both “open stub jpoles” and both have issues as you can see in the pictures.  They are good antennas and have there uses but really are not built for the conditions on the hill and probably just need to be replaced.
I think I covered it all, if not let me know or if you have questions.
JEREMY PRINE
KC7VCG
SECRETARY/TREASURER
CAPITOL PEAK REPEATER GROUP