Technical details of the Marion 444.125 Repeater
Posted Nov 28, 2007
Well gentlemen after months of work the repeater is finally finished. I
finished up the receiver tonight in about an hour. Amazing how a good
receiver tunes up! Alas I have done all of the controller programming
etc and the repeater is purring quite nicely at my parents house. I
have tested the audio with ht's and mobiles. I may need to adjust the
audio levels a little on TX after the repeater is on the mountain. I do
not want the deviation to get above 3 KHz to keep everyone's speaker
happy as well as keep the signal spectrally pure. There has been one
major change to the repeater. The CTCSS/PL tone is and will be 162.2
Hz. That is the final CTCSS/PL tone. It is required for access. If your
radio has CTCSS/PL decode the repeater also transmits a 162.2 Hz tone
so you can set that up. For you commercial radio users the repeater
also uses reverse burst so program your radio to use that. That
eliminates squelch tail.
I have performed a mod the receiver to make it like a Motorola Micor
squelch circuit. Basically the weaker a signal is into the repeater the
longer the squelch tail is after you release the ptt on your radio. If
you get a short squelch tail you are in the repeater just fine. If the
squelch tail is long you are weak/marginal. This helps identify places
that you may be able to work the repeater versus not. A link below
explains the theory behind this operation:
http://www.repeater-builder.com/micor/micor-bi-level-squelch-theory.html
The way I have the CTCSS/PL setup I will not be able to remotely disable
it. It can be removed by a trip to the repeater site which will
hopefully not have to take place hihi.
The controller has a voice ID mode that I will use to make announcements about club
activities, meeting times/dates, work days, test sessions, hamfest
announcements, net nights etc. I can program up to 10 sec of recorded
voice audio and have it setup to announce on a timed interval. This
could be a handy feature to use. If anyone wants something programmed
let me know and I will get it programmed in.
I would like to setup a day to get the repeater on the mountain and
running. It is ready to go just need to get it up there and installed.
Eddie KD4PXY can we do this on Sat December 8 2007? I would need a few
extra hands also. It would be too much for myself and Eddie to do by
ourselves. Larry AF4HX can you help out? Would need one other good
strong back. I can do the lifting with the other volunteer. The
repeater cabinet probably weighs 150lbs or so.
After doing some figures looking at the antenna, vertical radiation pattern on the
antenna at the site, I have came to the following numbers.
Our radio horizon at this site over perfectly flat ground (which we do not
have here hihi) is about 41 miles. So that is about an 80 mile circle
centered on the repeater site. I don't think we will see those
particular figures due to our terrain but it is very promising none the
less. The HAAT (height above average terrain) with the antenna on the
tower is about 820' so we have that to our advantage.
On the test bench at the house (as Calvin WD4PVE told me on the repeater
and in person.. "What happens on the test bench and what happens at the
site is two different things") the squelch on the receiver breaks
around .15uV and is full quieting around .4uV. That is very very hot. I
hope that it is not too hot for the site. We will just have to put it
in line and see how it plays.
That puts the receiver squelch
breaking at -123.47 dBm and full quieting about -114.95 dBm. That is
good on the test bench and quite hot.
The transmitter is putting out about 50W out of the isolator and will
be fed into the DB-408 antenna yielding 7.8 dBd gain.
Anyhow enough rambling that is where we stand now. We shall see how things
play on the hill now. So after almost a year and a half I have the
machine ready to go.
73 to all and lets keep UHF alive..
Shane KI4M
444.125 + 5MHz PL 162.2 HZ
---------------------------------------------
Sun Nov 5, 2006 11:36 am (PST)
Well here is an update on the repeater as of today. I went up to
Spruce Pine this past friday evening and worked on the repeater for
about 3 hours with Brannon KF4GUZ. He is helping mentor me a bit. He
gained knowledge from Calvin WD4PVE and is sharing some of the
information with me. I like to learn about this stuff..
Well his Bird died on us so we didn't get to do anything to the
transmitter or the duplexers but we did manage to get the receiver
tuned up. The RX is playing beautifully on 449.125. We tuned on the RX
for probably an hour and a half. Well the results were worth it. This
repeater does not have an internal pre-amp built it. Well after
Brannon worked his tuning magic we netted the following: RX squelch
breaks at less than .1uV and is full quieting at around .25-.28uV.
That is quite impressive considering no pre-amp is installed. With
those RX figures we have more than determined a RX pre-amp will not be
needed. The RX is very hot already so no need to add the possibility
of putting a pre-amp inline and bringing trash into the RX.
We are going to try to get together later this week and work on the TX
and duplexers. The transmitter/exciter is quite a bit easier to align
than the RX. The exciter in these repeaters is quite broadbanded so it
should not be too difficult to align. After opening the cabinet
Brannon noticed that the 4 can duplexers are identical to the ones on
443.925 repeater. He has tuned these before so, hopefully, that will
work out nicely as well. If 4 cans are not enough I do have a set of 6
cans to allow for more isolation/separation.
The controller is already installed and interfaced and is playing
quite nicely. Brannon was impressed with the internal speach of the
controller and the overall way it works. I think everyone here will be
very happy also.
The aluminum has arrived to make the mount out of and the u-bolts have
been ordered as well. Still waiting on the diplexers to arrive.
Hardline is ready and everything else is as well. So hopefully we can
get the repeater finished up this week and I will be able to deploy it
here at the house on a temporary antenna. That way I can use it from
work to chat with anyone who can work it. Range will not be that good
due to my limited height here at the QTH.
I am shooting to have the antenna on the tower and this thing fully
operational by April of next year. It is just to the point it will be
too cold and aggravating to try to mount the antenna this time of
year. I have thought about going to the mountain sometime this winter
and sweeping the 985 antenna to see if it is resonant at the 444.125
frequency. If it is within SWR range I might put the repeater up there
and use the 985 antenna temporarily until we can get the DB-408
installed. The pattern of the 985 antenna would not be very good but
it would be good enough to allow us to have it on the air and running
to work the bugs out. Lets hope I get all of those worked out b4 we
deploy to the mountain anyhow lol!
I apologize to everyone for this project taking so long but I want to
put something up that will give no problems. It has taken a lot of
time to source the pieces, assemble them together, etc. I am quite
certain that everyone will be proud to say this repeater is in our
hometown when I am finished. I am so excited it would make me happy to
have it on the air next week but alas that is just not going to happen.
As always if you have any questions or comments feel free to express
them here...
Shane KI4M
------------------------------------------------
440 Repeater update
Posted by: "Shane Autrey KI4M" iam4thapack@yahoo.com iam4thapack
Date: Sat Oct 21, 2006 8:47 pm (PDT)
Just wanted to give everyone an update on the 444.125 machine I am
building. I had fully operational repeater and controller ready to go
about a month back. I simply was not happy with the way everything was
working together so I sold the entire thing and started a new plan.
Well after hunting for quite a while several weeks back I sourced a
nice used MSR-2000 repeater from Ted K9MDM at MDM radio in Chicago.
This is a 100W commercial repeater. It is basically a base station
/\/\otorola Mitrek . It is a combination of Mitrek and Micor base
station parts. 146.985 WD4PVE repeater is a Micor base station. Ted
was very nice and threw in lots of extra spare cards for the station.
He is closing down and will be missed by many hams. Shame to loose a
fellow amateur who helped us out. Well the repeater is a commercial
unit capable of 100W but for our purposes I think we will shoot for
around 60W-70W out of the duplexers. That is more than I had
originally intended but will help fill in some holes a bit better.
Don't want an alligator machine thats for sure. Ted was also nice
enough to throw in a nice set of matching 4 can duplexers.
I also purchased a new ARCOM RC-210 repeater controller kit about a
month ago as well. Well about 10 hours of assembly netted a super nice
controller that is capable of a lot of things. A link is below for
our/your controller if you wanna look at its features.
http://www.ah6le.net/arcom/rc210/rc210.html
This controller will allow me to link with 3 different repeaters if we
desire and will also allow me to be able to add a weather receiver,
remote base,etc. I am always open to opinions on this. If you have an
idea you think might be worthy of investigating let me hear it on here
so everyone can comment. It has a built in DVR, multiple macros,
schedulers,etc. For the money there is not a controller on the market
that can compete. The firmware is updated about every month and all I
have to do is take my trusty lap top to the repeater site and update
it. Its a serial connection and works great.
The repeater antenna is here and has been for months now. It is a
Decibel DB-408B. Here is a link to that as well:
http://www.andrew.com/products/antennas/bsa/DB408-B.aspx
The antenna will more than likely be set up like the 985 antenna. What
I mean by that is with all the elements pointing in one direction. I
know that sounds crazy but trust me with the modeling software I have
run many many many plots on this. With the antenna being side mounted
at about 150' on the NE leg, and the width of the tower face taken
into account the antenna will have a more omni directional pattern
with all of the elements in line with each other. The only bad null on
the plot will be -5dB in roughly the direction of Curtis creek/Lake
Tahoma. The N and NE are great. That is the area(s) I want this
machine to cover anyhow so I made the plots work where the N was
covered best. Unfortunately it does have nulls but getting tower top
antenna mount is just not gonna happen.
I ordered some aluminum angle to mount the antenna with, again like
985 arrangement. It is here and I have already found the U-bolts I
need to get. They are available from Grainger so getting them will not
be an issue.
Diplexers have been ordered but are on backorder at this time.
Basically we are going to diplex the 1 5/8" heliax that 985 is using
now in order to avoid having to run another feedline up the already
full cable tray on the tower. I already have the 1/2" heliax ready for
the jumper from the 1 5/8 to the diplexer to the antenna.
Crystals have been here for several months now. I purchased these from
Bomar in NJ. They have been temperature compensated to the elements
and should be super stable.
I have received 2 service manuals for the MSR and am actively hunting
for the 3rd to complete the set that I need. You have to have 3
different books on these beasts. One covers the control tray and cards
exclusively. Another covers the VHF station and power supply etc. The
3rd, which I am still hunting, covers the UHF station RF components
only. The UHF does not have power supply stuff so that is why you have
to purchase the VHF book. Big /\/\ does some weird things..Might I add
these are NLA (no longer available) from Motorola so eBay is my only
option on these. The two manuals I have were new in packaging when I
bought them a few weeks back!!!
This machine will be setup like 985 in the respect that the pl will be
118.8. Please note this change. I had originally intended to use 146.2
but this machine came with those PL encode and decode reeds installed
so why not use them. To make things less confusing to Marion repeater
users use the same as the 985 machine. This machine will also be setup
as a dual squelch like 985. If you are in a fringe area using the pl
will keep the receiver open longer to cut down on flutter and fading..
As an interesting sidenote the controller does have the same courtesy
tone available to use as 985 does. What is the consensus of the group
on using this or using the same tone except just a bit faster than
985? I can do either or neither. I myself like the idea of the same
courtesy tone..
The repeater is currently playing just fine in test mode in my living
room hooked up to a dummy load so graciously loaned to me by a local
ham. It is in test mode right now so I can get everything right (or as
best i can) before we deploy to Grants mountain. I am awaiting arrival
certain piece of test equipment to arrive that I have purchased in
order to align the receiver,transmitter, and duplexers. This piece of
equipment will allow myself and Calvin to keep a very good eye on the
two repeaters. I will elaborate more on this in future mailings.
Well thats about it for now and thanks for reading this long update on
the repeater progress. Any questions or comments welcome...
Shane KI4M 444.125 + 5 MHz PL 118.8