W4ZT Repeater Log

This log is here to give you an idea of what the latest happenings are with the repeaters. I'll try to keep it updated as soon as I can when something happens that impacts the operation of the repeater. If you have any questions, please contact me. Tony - W4ZT


August 15 , 2004 - Replaced the six 8-3/4" RG8 jumpers on the duplexer with same length Andrew FSJ1-50A Superflex Heliax.

July 25, 2004 - The BIG spark came to visit. There was no major damage to the repeaters but the battery charger for the VHF backup batteries smoked. Also lost a DJ-130 and lots of consumer electronics.

December 30 , 2003 - The VHF (146.625 MHz -600/100 Hz) repeater is no longer a Spectrum 1000. It is now a GE Mastr II. I'll have pictures up on the web as soon as I can. First tests around town indicate it is already working better than the Spectrum.

September 7 , 2003 - The UHF (442.125 MHz +5/100 Hz) repeater is on the air at the full power level of 100 watts. CTCSS tone decode and encode working. Enjoy!

April 15, 2003 - The UHF (442.125 MHz +5/100 Hz) repeater is on the air. Still have lots of work to do but the signal is there.

March 16, 2003 - New dual band Diamond X510 antenna installed.

January 2 , 2003 - ID changed to say "zed" instead of "zee" to reduce confusion over the call sign.

November 5 , 2002 - I received my vanity call sign today so the repeater call has now officially changed to W4ZT.

October 13 , 2002 - I shortened the hang timer so that the repeater stays keyed only 2 seconds after the courtesy beep. The delay between the loss of input carrier (Carrier Operated Relay - COR) and the courtesy beep is normally 1.0 seconds. I shortened the COR drop to courtesy beep timer as well as the hang timer both to 0.5 seconds between the hours of 2300 and 0700. During those hours, there is no voice ID, only CW.

September 26, 2002 - After quite a few days of squeals, squawks, chirps, noise and desense I spent this evening working on the repeater attempting to improve the situation. The outcome of this effort was a very hot receiver, a transmitter with good power output and a confirmed duplexer problem... AGAIN. The last time I had a problem like this with the duplexer I had to open the cans and clean corrosion on the inside. It isn't like the duplexer is in a damp environment. It does live in the laundry room but it isn't damp there. It's just that bare copper gets some corrosion on it. The problem is the tuned line within each copper cavity. The RF currents are very high on these tuned lines and it is there the parts are designed to move against each other for tuning. The resulting problem is poor conductivity in a critical spot. When the high RF currents flow through these corroded joints you get "semi-conductor" effects and micro arcs and everything goes to pot. I placed an order on Friday, 9/27 for a pound of Cool Amp silver plating powder (which costs $140+) and when that comes in we'll have a duplexer work party to completely tear it apart and refurbish all six cavities. This will be a big job and the repeater will be off the air during this time. It may take a week for one person or proportionally less time with your help. I'll be sending an email to let you all know when the stuff arrives and a date we can begin.

July 22, 2002 - Today I climbed up the tower again to install the repaired antenna. The repeater is now back on the air and appears to be performing well.
Click here for details

July 21, 2002 - Today I climbed up the tower to investigate the antenna/feed line problem. The antenna was found to be bad! I removed the antenna and took this opportunity to remove the Christmas lights from the tower as well. On the ground, the antenna was disassembled and the problem was found and fixed.

June 30, 2002 - The repeater is down. Initial checks show good power out and the receiver working yet the range is extremely limited. Very high SWR has been found between the duplexer and the feedline. I was out of town but I have been told there was a big storm here the evening of Thursday, June 27, 2002. Looks like Mother Nature has struck again.

The repeater is operating on the four dipoles about half way up the tower. Patched to this antenna with a 25 ft RG58 jumper and considering the feed line is not insulated, operation will be a stroke of luck for this temporary rig.

April 8, 2002


Last week the repeater experienced a catastrophic failure of the internal 12 volt DC power supply. I was out mobile and on the air talking with Bob - KG4RDC at the time and the repeater just died. We had no idea what was wrong at the time. In fact, Patty and I were worried so we came straight home to check on it.

As it turns out, the failure in the internal analog power supply appears to be from poor design and construction but I guess I can't complain after over ten years. The supply had a huge heavy transformer supplying about 18 volts AC to a bridge rectifier. The DC output of the rectifier was fed through a parallel combination of a 0.1 OHM 20 watt and a 0.2 OHM 20 watt resistors. The DC then went to 3 10,000 uf electrolytic capacitors on the regulator board. The parallel resistors were running extremely hot. When the resistors were installed one was fastened up tight to the other and the remaining leads were cut off. Then the two resistors were soldered together. The combination of the two resistors were then soldered using short leads from one of the resistors to a terminal strip.

Over time, the heat from the resistors had melted out the solder from the junction of the two resistors. That led to a poor connection and eventually arcing of the connection. This arcing began to eat at the metal in the leads and eventually one of the leads failed. When that happened, no current from the rectifier could reach the filter or regulator. The entire system was dead.

You ask the same question that I did... "why didn't it switch to emergency power?" Well, the way the emergency power relay is set up is that it is powered by 120 volts AC. The reason I did that was to try to keep the system running at the time the power failed. So, though the 12 volt supply failed, we still had commercial power so no switch over.

I spent a good bit of time trying to come up with a good repair for the analog supply. I did manage to build up a bank of resistors which would work. Unfortunately, it generated a great deal of heat. In fact, I used ten 5 watt resistors and they all ran hot enough to burn your finger if you touched it. I studied this for a long while and decided to rip the entire analog power supply out of the repeater and replace it with an up to date switching supply.

After removing the transformer, bridge rectifier and its heat sink, pass transistors and their heat sink and the filter capacitors, the repeater was actually light. For once I can lift it with one hand.

I brought out leads from the appropriate place on the old regulator board and attached a Samlex SEC1223 12 volt 23 amp DC supply which I purchased from RadioShack.com during their store closing sale. The repeater worked and ran cool. Welcome home new power supply!

While the major modification to the power supply was under way I decided to make the update so that the controller would automatically change messages when switching from commercial to emergency power. This mod was done and now works properly. While the repeater is on commercial power, you will hear the normal voice message and the courtesy tone is the normal 3 tone "boo bee beep" you hear every day. The CW ID will be "de wa4upe/r". When on emergency power, the repeater will change voice messages clearly noting that it is on emergency power. The courtesy tone will change to a lower pitched two tone "bee boop" that is very different from normal. The CW ID will be "de wa4upe/rep" (repeater emergency power). The repeater will be on slightly lower power while on emergency power. The emergency power batteries will hold the repeater during normal operation for over two days. I will occasionally unplug the commercial power from the repeater for a while to test the system and cycle the batteries. It is always good to note that the system is on emergency power. There should be no reason to hear the emergency power identifications if the system is NOT on emergency power.

The only remaining problem I know of is some desensitization of the receiver. Part of that appears to come from having the Christmas lights on the tower. They will be coming down soon. The other problem may stem from something loose in the system. I've checked everything inside so the next thing will be a full careful inspection of the feed line from bottom to top, all the connectors and every nut and bolt in the antenna field.

I hope you all will continue to enjoy using the repeater as much as I do.


Last update was August 16, 2004