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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
Friends,
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.
73,
Tony
Last
update was August 16, 2004
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