Pages: [1] 2   Go Down

Author Topic: Ready made or build it yourself?  (Read 52009 times)

W6LAR

  • Member
  • Posts: 40
Ready made or build it yourself?
« on: February 05, 2011, 06:53:47 PM »

As a repeater owner and builder I was wondering how many other repeater owners have built their own or assembled their repeater out of something like Motorola or GE equipment. Or just purchase a ready made unit like an Icom. Share your experiences for the rest of us.

Larry W6LAR
147.180+ 88.5 / 445.340- 88.5
Redlands/Yucaipa/Calimesa/Colton/Highland and San Bernardino CA.
Logged

K4JJL

  • Member
  • Posts: 1194
RE: Ready made or build it yourself?
« Reply #1 on: February 06, 2011, 09:15:24 AM »

Never liked Icom repeaters.  Interfacing third party equipment is too hard.  The plugs are non-standard, the voltage levels are weird, and the input/output impedence for audio is non-standard, as well.

I've been mainly working with GEs Mastr IIs and Motorola MSF5000s the past couple years.  They are kinda quirky, but everything interfaces without much hassle.  The GEs are crystal bound, which puts a little delay and adds a little cost, but they work just fine.  I know a couple friends who have GE MVPs for packet digipeaters that have been on the air non-stop for 18 years.  Crystals haven't drifted at all and the radio is still putting out full rated power.

Logged

K1CJS

  • Member
  • Posts: 6293
RE: Ready made or build it yourself?
« Reply #2 on: February 07, 2011, 09:18:31 AM »

Sometimes the do-it-yourself way is better.  That way you can have interchangeable units for the transmitter, the receiver, and--if necessary--the controller.  If done in that matter, you don't have to have an entirely separate system or have excessive downtime if the repeater system goes down.

Yes, a commercially made unit looks better and more professional, but when the cards are down what is more important--seeing it?  Or being able to use it?
Logged

W6LAR

  • Member
  • Posts: 40
RE: Ready made or build it yourself?
« Reply #3 on: February 07, 2011, 10:00:34 AM »

 ;) Good answers both of you. My 2M and 440 use Motorola Mitrek radios. I have LOTS of spares ready to go in case of a glitch. They have been very reliable and have run 24/7 for over 15 years. The controller is a Link Com and so far no trouble either. Since I've done the hard work myself I feel like I can spot any problem and take care of it in a timely manner and keep the system up and running with very little down time. It helps me to be very close to my site. Only 15 minutes and I am there. 

Logged

KE4DRN

  • Member
  • Posts: 3746
RE: Ready made or build it yourself?
« Reply #4 on: February 07, 2011, 06:21:00 PM »

hi,

Our radio club replaced older repeaters with
new Kenwood models.

73 james
Logged

K4JJL

  • Member
  • Posts: 1194
RE: Ready made or build it yourself?
« Reply #5 on: February 08, 2011, 02:09:17 PM »

For those of you who are using newer pre-packaged repeaters, how is the selectivity?  When you're using a mobile, selectivity isn't really an issue, but when you're on a crowded roof or tower, suddenly adjacent channels become a problem.  Older radios usually have a beefy, tunable preselector.  Do Kenwood and Icom's newer models include these?  Most of the late model repeaters seem to be built out of 2 mobiles, a notch/notch duplexer, a simple controller and a power supply all jammed in one 3u rack mount box.  Do they still include a tunable front-end and an image filter like the older models?
Logged

N1OFJ

  • Member
  • Posts: 18
RE: Ready made or build it yourself?
« Reply #6 on: February 10, 2011, 06:36:45 AM »

We have been using the Motorola Micor repeater, along with Motorola SpectraTac receivers (Micor guts) and Motorola SpectraTac voting comparator....this is without a doubt the best repeater equipment made for the analog world ever.  Very select receiver with decent sensitivity, ultra clean transmitter, clean crisp audio, and the best squelch circuit I have ever heard. 
Bottom line, it never breaks, can take power hits and survive electrical storms...does not miss a beat.  No wonder why in it's day it was the choice of public safety.  I got my system after it was being retired due to a system upgrade.  I went through it all, replaced all electrolytics in all the power supplies and in the guard tone encode boards (need 2175 hz status tone for voting) had the channel elements sent out for professional compensation, made the necessary part changes to bring it down to 440....it was well worth it...the equipment has been running 8 years straight with no breakdowns to speak of.  Only things I did different was slap a new set of TX/RX bandpass/band reject duplexers on it along with a circulator, bandpass filter unit hanging off the PA.
Logged

K4JJL

  • Member
  • Posts: 1194
RE: Ready made or build it yourself?
« Reply #7 on: February 10, 2011, 01:43:56 PM »

What you just described is the exact same high band station I built for the Gold Coast club in S FL, with one slight change.  Remove "Motorola Micor" and replace it with "GE Mastr II".  GE was the choice of public safety down here in S FL.  Miami-Dade is still running EDACS on Mastr IIIs (except it's now called GE/Ericsson/MA/COM/Harris/etc).  The GEs I got were old Turnpike and Southern Company stuff.  FPL used them, too.  This stuff was designed by broadcast engineers who designed multi-kilowatt systems.  Only real problems I've had were dried out capacitor related (but I've been dealing with that in my big screen TVs, my pinball machines, my Sega GameGear, my MSF5000s, etc. etc).  One thing I've noticed between GE and Motorola: GE seems to be a little more widebanded as far as tuning range goes.  It's just as selective as a Motorola, but the ranges are larger and can be "bent" a few MHz more.

I've got 2 GE voters tied together for 12 total RX channels.  I've even got the Aux RX drawers (analogous to the SpectraTAC receivers) with 1950 status tone generators (GE just had to be a little different).  My remote crossband RX stations are built out of GE Mastr II mobiles (shoehorned VHF RX into UHF mobiles).

Since I'm running an SCOM 7330 controller (3 independent ports), I've decided to add 2 more repeaters to the mix.  A UHF Mastr II and a 900 MHz Motorola MSF5000.  The MSF was interesting to interface to the voter.  I had a SpectraTAC board for the MSF, but I had to clip random resistors and jumpers to get the status tone from 2175 to 1950.

The final addition to the repeater system will be 6m Micor and 10m Motrac paging transmitters (sitting in storage, for now).  I'll end up doing a split site system with those (since duplexers will be a problem).  I'll get a 6m and 10m Mastr II Aux RX and add them to the voter.  On another site, I'll have a link RX listening to the UHF repeater and repeating on 10m and 6m with a CAT-200 (no drop out delay, no TOT).

The real project is going to be interfacing the 12 "selected receiver" outputs to the 4 aux inputs on the SCOM controller and decoding them with the macros in the controller.  I'll do this so everyone will know what receiver you're coming in on.

If you need SpectraTAC stuff, let me know.  I've got 6 or 7 receiver chassis and a comparator chassis, along with 10 or so brand new comparator cards.  I decided to go with GE voters since parts are very, very plentiful among 3 of my friends.
Logged

AD4U

  • Member
  • Posts: 2587
RE: Ready made or build it yourself?
« Reply #8 on: February 11, 2011, 08:29:29 AM »

I own three repeaters.  53.210, 146.670, and 444.975.  All are GE Mastr II.  They have been on the air continuously since 1988.  The only problem I had was the two meter PA went out once.  I bought a truck load of spares for $15 each at a State sale a number of years ago.

Dick  AD4U
Logged

KB1GTX

  • Member
  • Posts: 505
RE: Ready made or build it yourself?
« Reply #9 on: February 12, 2011, 05:07:21 PM »

I put together 3 regency 10 channel programable radios as a temp uhf repeter with a simplex link to vhf.
It works off the squelch voltages and the ctcss tones to work the key ups.
Also by changing the sub tone input to the uhf  can change the vhf frequency by using the led driver voltage of the led driver on the rxing uhf unit.

output is 25 w uhf and 20w vhf

http://i631.photobucket.com/albums/uu39/dav850/DSC00183.jpg
« Last Edit: February 12, 2011, 05:12:58 PM by KB1GTX »
Logged

N0FPE

  • Member
  • Posts: 397
RE: Ready made or build it yourself?
« Reply #10 on: February 15, 2011, 04:24:22 AM »

OK I will toss in my 2 cents worth. I am along with another ham tasked with keeping the clubs 2 repeaters working. A few years ago we dumped the hodge podge of mobile and patched together commercial radios and homemade controllers. We went with all GE MASTR II equipment. Not converted base stations but true blue repeaters. A VHF and a UHF. In the process we aquaired a large stock of parts for these at the local city surplus auction for next to nothing. We now have 2 repeaters that run without a hitch for 2-3 hours key down during the morning drivetime. The GE power supplies don't even break a sweat. The repeaters are both set to provide 50 watts out of their respective duplexers and the audio has been worked until you can not tell the difference between the 2 repeaters. we are using a RLC Club controller but also have the GE cards to plug in if the RLC dies. I find the GE equipment stable and very easy to work on. And of course there is so much of this stuff available that parts are no problem.
I personally have a GE MASTR II UHF repeater here at the house that has been running 24/7/365 for 4 years now without a single hiccup. I am using a P&S 508 controller in it and find this combo to be a good basic system.
SO I prefer to build my own from existing commercial equipment. For me this works and the price is right! ( free or almost free)
Logged

KD8BIW

  • Member
  • Posts: 7
RE: Ready made or build it yourself?
« Reply #11 on: March 01, 2011, 10:37:53 AM »

Build It!  I have built and maintain several amateur repeaters in the 144, 220, and 440 bands. A VHF GE MASTR II Station converted to repeater with CAT-1K Controller.  A VHF GE MASTR EXEC II mobile converted to repeater use with a CAT-1K and external 120W power amp. A Homebrew 220 repeater with Hamtronics Rx and Tx, Comm-Spec tone panel, and Uniden 120W power amp. A Homebrew 220 repeater out of GE MASTR II mobile parts put into a new rack mount cabinet, and a 100W EF Johnson power amp.  A UHF GE MASTR EXEC II mobile converted to repeater service with an SCOM-7330 Controller and an external Trilectric 100W power amp.   I also maintain several "off the shelf" repeaters, including Kenwood and Hamtronics.  These work ok, but the homebuilt units sound better as I can shape the audio just the way I want it.  And if your going to be getting into owning a repeater, you should know how to build it, work on it, fix it, and maintain it.  Not just plug it in and use it!  That's my 2 cents.
Logged

WC4V

  • Member
  • Posts: 73
RE: Ready made or build it yourself?
« Reply #12 on: March 02, 2011, 02:14:55 AM »

My experience with them, is that I would take a commercially built one, any day of the week and twice on Sundays.  The pieced together ones around here, were constantly having issues, to the point where people wouldn't even bother to attempt to use them.  The city I used to live in, has had a commercial unit on the air continuously for over 20 years with no problems whatsoever.  I rarely can be found above 50.200, so it doesn't bother me.  Just my two cents.

WC4V
Logged

NA4IT

  • Member
  • Posts: 363
    • HomeURL
RE: Ready made or build it yourself?
« Reply #13 on: March 05, 2011, 07:37:36 AM »

Well, I deal on a regular basis with a converted Motorola Mitrek on 70CM, 2 GE MastrIIs on 2M, a HiPro on 2M, and a HiPro on 70CM. I have also worked with a Kenwood TKR-750 in the past, as well as some Icom and Alinco mobiles.

The Mitrek is an easy conversion project. It also has turned out to be the the repeater that gives me the LEAST of problems, and actually does 40W out (fan on heatsink). I have actually built one of these with the tone board and controller contained inside the case, and a 50W mobile duplexer that worked well. (It was a 16W output radio). I normally use the speaker and control head so it has a "local" control system, using switches to break the mic and speaker connections.

The GE MastrIIs are a learning project for me. I've had problems with TX exciters and power amps.

The HiPros are a pretty good machine, and work well as exciters. If you have a good location, the power amp add ons are good. Everything is standard discrete components, no surface mount. They also come in a nice rack mount case. On ours, we run external MOBILE amps with big heat sinks and fan banks controlled by a timer circuit keyed by the PTT. And, they HAVE NOT failed.

(NOTE: the fan timer I use is a CK1614 Multi Mode Timer from Carl's Electronics. It is a kit, and I have never had one fail.)

The Kenwood TKR-750 was OK, but it does require very careful tuning which is all done by software.

As far as using mobiles for a repeater, I see no problem doing it, with one exception... they were not designed to run at full power key down for a long time. That said, run them on low power as an exciter into an external amp. The plus, is that you have a repeater that is fully frequency and tone agile. I would prefer the Alincos, simply because that almost all of the case is heat sink, and they have the rear panel interfacing port, with everything you need brought out the back. Don't forget the fans!

Main thing to remember on building a repeater system is good location, good antenna, good heliax, good duplexer, and good sensitivity in the RX.

NA4IT
Logged

NA4IT

  • Member
  • Posts: 363
    • HomeURL
RE: Ready made or build it yourself?
« Reply #14 on: March 05, 2011, 07:46:25 AM »

A couple of other thoughts...

Yeasu repeaters... run from them...hard to interface...and prone to fail.

Power supplies... if you plan to have battery backup, look at an RV type power supply with big computer UPS batteries, something on the order of 100maH or above, or a bank of 2 or more. We use the supplies from http://cascadeaudio.com/power_converters/power_converters.htm. Unless you are running extremely high output power, a 30 or 45 amp supply will work well. This setup does away with the fancy, prone to fail AC / DC changeover switching. You might check some local battery builders, as sometimes they get "one year takeout" UPS batteries, where a company changes every year, need it or not. Take a look at my website http://www.qsl.net/na4it and you will see what I am referring to. I run the same setup in my shack. Another plus is, most of those batteries will fit in a rack cabinet (but put a board under them).

NA4IT
Logged
Pages: [1] 2   Go Up