Digital Capable Repeater using Maxtracs Specs

The Pager Geek · Post by **The Pager Geek** » Mon May 02, 2005 8:02 am

Ok, after much refinement and testing.

Astro Capable Maxtrac Repeater

This is a Microsoft Visio drawing. If you don't have Visio, you will need Visio Reader to read it. It's a free download from Microsoft.

Visio Reader Download

This modification is for Ham use only. It's not meant for commercial use, and god forbid NOT Public Safety use.

Remember this mod is transparent. ANYTHING it hears that breaks squelch, including intermod and spurious noises, will get repeated. Choose your sites wisely.

tpg

[made sticky by Alex]

Fuel4300 · Post by **Fuel4300** » Mon May 02, 2005 1:38 pm

Wow. Thanks for the diagram. This will be high on my list of projects for the summer.

How does this differ from a factory or home-brew RICK?

Mike

The Pager Geek · Post by **The Pager Geek** » Mon May 02, 2005 1:54 pm

The TX audio must be routed to the new point of entry, otherwise, it gets filtered and 4 level FSK won't pass.

RICK's point of entry was filtered, and the RICK has adjustments not needed. Alhtough I suppose you could use a RICK as transparent enable / disable as long as the audio doesn't get routed thru it. Only the call alert I/O.

tpg

CTAMontrose · Post by **CTAMontrose** » Mon May 02, 2005 2:20 pm

these things do work good, ive been using one as a same band ASTRO link repeater for a few months..

would recommend doing the maxtrac power mods and putting active cooling on the radios as these puppies get hot.

get them aligned for proper ASTRO deviation and they work great.

mancow · Post by **mancow** » Mon May 02, 2005 3:58 pm

Cool. Thanks for being the one to finally put it in a form that can be seen.

I just built a portable repeater from two king LPH handhelds. I would like to make it pass securenet but I'm struggling with the same issue of how to select the proper audio path.

Short of using some sort of pl decoder that senses analog and a specific tone to switch in the analog audio path I can't figure out what to do. I would like to make it automatically sense what type of modulation is going through it but I guess that's not going to happen.

mancow

The Pager Geek · Post by **The Pager Geek** » Mon May 02, 2005 4:15 pm

12K data (Analog Securenet) won't pass thru this either. That's a bit too much. 9600bps (4800 Baud, 4-level) will.

[edited terminology to make wowbagger sleep at night]

jnglmassiv · Post by **jnglmassiv** » Mon May 02, 2005 6:03 pm

Wow..really nice work.

You know, you can save Visio drawings as jpegsto make this type of distribution easier. FYI.

RADIO43 · Post by **RADIO43** » Sun May 08, 2005 5:23 am

Pager Geek,

Is it possible to do the same with two GM300's. I am sure it is, but just want to ask before we start the project. Thanks in advance.

Radio43

The Pager Geek · Post by **The Pager Geek** » Sun May 08, 2005 11:18 am

Yes, different locations but the principal is the same. It's been done.

tpg

radio-link · Post by **radio-link** » Sun Jun 05, 2005 11:07 pm

The Pager Geek wrote:12K data (Analog Securenet) won't pass thru this either. That's a bit too much. 9600 Baud 4-level will.

I did a repeater with some old crystal controlled radios, doing FM, APCO25 and 12kbit securenet just fine. The old stuff sometimes is much easier to adopt to those new modes :-)

firemedic4 · Post by **firemedic4** » Mon Sep 05, 2005 4:20 pm

Would it work with a gr1225 ???

radio-link · Post by **radio-link** » Mon Sep 05, 2005 8:02 pm

firemedic4 wrote:Would it work with a gr1225 ???

I do not know this radio, and I never tried...

RADIOMAN2002 · Post by **RADIOMAN2002** » Thu Sep 15, 2005 4:27 pm

While this not usefull for Astro, or at least I havn't tried it yet, using MX-S or crystal version portables work great for Securenet. You will need either a Secure MX portable as a reciever or a Securenet box from a Syntor or SyntorX to get the reclocked digital signal, then merely rerout to the PL input of the radio.

WB5ITT · Post by **WB5ITT** » Sat Dec 03, 2005 10:27 am

Would this be possible with Astro Spectras? I have a need for this on commercial service and if I can use Astro Spectras to require the correct digital code to key up the opposite transmitter, it owuld be perfect!! (it would actually be two back to back radios...one talking to a Quantar, the other talking to mobiles in a rough area that cannot talk directly to the main rptr). I could use the BUSY light off the head to key the opposite transmitter..of course I will need 4 radios to do this full duplex in both directions (but I have plenty of spares!!

HMM time to hit the bench with this idea..

The Pager Geek · Post by **The Pager Geek** » Sat Dec 03, 2005 1:49 pm

http://batboard.batlabs.com/viewtopic.php?p=59727#59727

Read this thread. You may be able to double vocode the audio, but not a passive repeater like the maxtracs.

tpg

USGOVTECH · Post by **USGOVTECH** » Sat Dec 17, 2005 12:11 pm

I have done thie with the Icom 1821D radios and 2721D radios. They work like a champ. Just put fans on the TX radio. I have 3 portable systems in use to date with many more to come, However only one NAC ,and TG can be used.

giantcake · Post by **giantcake** » Tue Jan 10, 2006 12:16 pm

You can download a driver from Microsoft to allow Explorer to view the Visio drawing. Firefox seems to work OK also. Works here anyway. This is an alternate program location:

http://ets.strose.edu/Resources/softwarelist.asp

-Steve

FYI, Cool idea, will have to work on trying this out, my Astro Saber will be happy!

flecom · Post by **flecom** » Tue Feb 28, 2006 11:42 am

do you think this repeater might pass other digital voice modes? like for example GE AEGIS or ProVoice?

Zap · Post by **Zap** » Sat Apr 15, 2006 8:38 am

[quote="The Pager Geek"]12K data (Analog Securenet) won't pass thru this either. That's a bit too much. 9600bps (4800 Baud, 4-level) will.

[edited terminology to make wowbagger sleep at night][/quote]

What would have to be changed to force it to pass securenet, theoretically.

zulu · Post by **zulu** » Tue Jun 27, 2006 9:19 pm

Wow, gives a whole new meaning to astro repeaters.

bwigg · Post by **bwigg** » Mon Jul 10, 2006 10:41 am

I found a program over at Radio Reference named the Knack. It decodes NAC codes. I haven’t tried the Knack, but I was wondering if it would be possible for someone to write a program similar to the Knack to decode the NAC of a receiving radio and use it for a COR input to a controller? It seems if it can decode and display the NAC ID, with a few mods to the code it could be changed to allow serial port control for a specific NAC. If that would be possible this would solve the problem of running a wide open transparent repeater for IMBE. You could write the software to allow only specifics NACs to give you a low or high on one of the serial port pins. You could use this signal similar to a digital COR signal line. If the proper NAC is present it would allow a repeater to key, if not it will not key up on noise or skip.

This could be run a cheap laptop or PC. Since there are thousands of low end machines laying around.

Would this work? Or am I just delirious from the heat?

N9LLO · Post by **N9LLO** » Fri Jul 14, 2006 4:17 am

bwigg,
I havent been able to find the program you mention. Cou you post a link?

Chris

MattSR · Post by **MattSR** » Fri Jul 14, 2006 4:53 am

We are massively off topic but here it is:-

http://www.radioreference.com/forums/sh ... hp?t=32528

MattSR · Post by **MattSR** » Sat Aug 12, 2006 12:07 am

How far out of band can these puppies go? If I were to set one up it would have to rx on 433 and tx on 438.. Is this possible with maxtracs or radius?

Thanks,
Matt

PhoneMan · Post by **PhoneMan** » Thu Sep 07, 2006 8:36 am

Ive been trying to use a GM300 for the transmitter, GE master II reciever.
I found the COR time faster and audio was alot flatter with the GE reciever, problem I am having is the decode at the other portable. The radio (other p25 radio not repeater radios) dosent pass audio like its trying to decode and then gives up and processes it as analog noise. Help me out here guys, audio levels are below clipping and dev set at 2.3k. Got audio from vol/sql high (buffered discriminator) going to the TX flat audio pin in on the GM300. I canot see anywhere on the GM300 that has a TXA printed on it like the Maxtrac. Any ideas will help alot, works perfect with analog and DPL...just not p25. Thanks

bellersley · Post by **bellersley** » Sun Sep 24, 2006 4:47 pm

Well now. I have a nice MSF5000 sitting here not doing anything useful. I wonder if you could use the theory and such in this "hack" to work on an MSF. Or maybe even a GR1225. That'd kick a$$.

mancow · Post by **mancow** » Wed Nov 15, 2006 7:52 pm

It may be a rough way to do it but is there anything about the IMBE undecoded "audio" that is rhythmic enough that a circuit could somehow discern it from regular analog transmissions?

I'm thinking of something along the line of a pl type decoder that sees something unique in the modulation and can trip a logic line.

Post by **wavetar** » Thu Nov 16, 2006 1:08 pm

bellersley wrote:Well now. I have a nice MSF5000 sitting here not doing anything useful. I wonder if you could use the theory and such in this "hack" to work on an MSF. Or maybe even a GR1225. That'd kick a$$.

Absolutely, according to TPG in this thread:

http://batboard.batlabs.com/viewtopic.p ... f5000+imbe

I don't believe he ever publicly released the MSF details like he did with the Maxtrac. Perhaps he will if he sees this, or you could drop him a PM.

Todd

RADIO43 · Post by **RADIO43** » Sun Jun 24, 2007 9:25 am

Guys,

HELP, I am ready to go here but looking for instructions to use GM300's. If anyone has any documentation or instructions on the procedure to use GM300's for this project, please forward. Thanks as always.

Kyle

emsbuff3240 · Post by **emsbuff3240** » Tue Jul 17, 2007 11:24 am

Can anyone that has tried this confirm that this works(2 maxtracs)?

Thanks
-Jon

Post by **alex** » Tue Jul 17, 2007 12:35 pm

emsbuff3240 wrote:Can anyone that has tried this confirm that this works(2 maxtracs)?

Thanks
-Jon

I've heard it work a couple of times. I know I've used at least one built by the author of the modification.

-Alex

zulu · Post by **zulu** » Thu Jul 19, 2007 4:52 am

I wonder if the same would go for the CDM series?

SlimBob · Post by **SlimBob** » Wed Oct 31, 2007 10:01 pm

Yes, but will it pass D-Star?

*ducks*

WV8VFD · Post by **WV8VFD** » Wed Dec 05, 2007 9:07 am

What i want to know is, could you have a Astro Spectra for recieve, and port the audio from it into the mic. port of another Astro Spectra, or the XTL series for that matter?

bellersley · Post by **bellersley** » Wed Dec 05, 2007 9:13 pm

KD8CPP wrote:What i want to know is, could you have a Astro Spectra for recieve, and port the audio from it into the mic. port of another Astro Spectra, or the XTL series for that matter?

Yes you certainly could. However. The re-transmitted audio won't be as good as what you'd get from the Maxtrac pass-thru repeater. In your example, you would be "double vocoding" which will most likely lead to considerable audio quality loss. Any "artifacts", that is, packet losses and other digital "noise" would be greatly increased in the repeated audio.

If the RX signal is very strong and the decoded audio has a very low bit error rate, the re-transmitted audio won't be bad at all, but as soon as you start getting iffy RX audio, expect TX audio to go down the tubes.

But, if you have two astro radios sitting around and want to give it a try, you might find it works just fine for you.

libuff · Post by **libuff** » Sat Dec 08, 2007 12:19 pm

SlimBob wrote:Yes, but will it pass D-Star?

*ducks*

i think its best answered by asking another question... whats the bitrate of D-Star vs the bitrate of ASTRO

radio-link · Post by **radio-link** » Mon Mar 10, 2008 2:38 am

radio-link wrote: I did a repeater with some old crystal controlled radios, doing FM, APCO25 and 12kbit securenet just fine. The old stuff sometimes is much easier to adopt to those new modes

OK, now I have set up a repeater with two GM1200 (european MTP1327/1343-trunking radios in conventional mode, Renaissance-series M01RFL9CK4AN), and D-Star passes quite good through it! Unfortunately I still can not program the Astro Sabers due to "codeplug to new" to the repeaters frequency, so I could not test if it works for P25, but I guess it will do.

The repeater is described at http://www.db0fue.de, but up to now only in german. Maybe I will find to translate the site into english druing the next one or two weeks, at least the technical details.

What I did is simply program both radios with "data channels", connect CSQ to PTT and demodulator out to modulator in. That was it

radio-link · Post by **radio-link** » Fri Apr 18, 2008 9:40 am

radio-link wrote:... so I could not test if it works for P25, but I guess it will do.

Update: D-Star and P25 work just fine; also in a cross band repeater setup with four radios (2*146 MHz, 2*440 MHz) it works great and is able to connect both bands together, FM, D-Star, P25, whatever you want to use. The "live" repeater however still is 440 MHz only, I do not have a frequency assignment for 146 MHz for it - so it was just a test on the workbench.

W1HVN · Post by **W1HVN** » Tue Dec 16, 2008 3:16 pm

Seems like this post is slightly ancient, however if I could revive it with your help...

1. For whatever reason after downloading the application (maxtrac how to file) to open the file, it won't open. Any suggestions?

2. To be able to coordinate a pair on VHF, we will have to have a NFM 12.5k spacing machine, is this Maxtrac and/or MSF modification plan a NFM or standard 25k deviation repeater?

3. Has anyone been able to enable a NAC computer controlled decode COR signal by using Knack or similar PC programs? Something that will see the NAC, enable the serial port, a box to convert the serial info to a high/low pulldown for a simple controller?

Thanks to those who have first hand knowledge on this project.

W1HVN · Post by **W1HVN** » Tue Dec 16, 2008 3:32 pm

I got the visio reader to work, so here is a new very important question...

- Will this work with two VHF GM300s (Maxtracs)?

- Hard to tell by this schematic if when in non-PL "APCO" transparent mode, does the transmitter stay keyed all the time or does it only engage on a COR signal? I didn't see any sort of a "controller" in there for this logic.

I hope it would work on VHF and be capable of NFM? If I am correct, isn't ASTRO mode done in NFM mode by the user radios automatically anyway?

Thanks!

radio-link · Post by **radio-link** » Tue Dec 16, 2008 8:42 pm

W1HVN wrote:I got the visio reader to work, so here is a new very important question...

- Will this work with two VHF GM300s (Maxtracs)?

- Hard to tell by this schematic if when in non-PL "APCO" transparent mode, does the transmitter stay keyed all the time or does it only engage on a COR signal? I didn't see any sort of a "controller" in there for this logic.

I hope it would work on VHF and be capable of NFM? If I am correct, isn't ASTRO mode done in NFM mode by the user radios automatically anyway?

Thanks!

I did not use this schematic, but with my GM900/GM1200 setup I used the carrier squelch to key the transmitter. Of course it would be possible to find other solutions, but for me it works just fine this way. It allows usage of FM, P25 and D-Star on one repeater.

mancow · Post by **mancow** » Tue Dec 16, 2008 9:31 pm

I have mine setup with two maxtracs and a TP-3200 tone panel running in carrier squelch mode. I was able to retain the use of the controller features such as hang time and CW ID by modding the controller with a small reed relay. What happens is that the LED in the panel that signals the presence of a carrier runs the small relay. When the relay closes it basically eliminates all the signalling features of the panel and makes a straight audio path through it. That keeps things clean for the use of P25 or DStar. When the LED goes dark the audio path is reconnected and the CW ID is played normally. It makes for a nice silent hang time as well. An end of transmission tone is sent by the transmit radio which is programmed with a short two digit DTMF Id set to post transmission. The setup is placed in a 19" rack and connected to a Milcom 160 watt amp that feeds a set of Wacom duplexers.

W1HVN · Post by **W1HVN** » Sat Jan 31, 2009 8:38 pm

Ok, we are in the process of putting together a cple GM300s on VHF. Here is our question, same question that was asked back in 2006, with no response. Maybe someone has done this mod with a pair of GM300s. If anyone has done this, please send a reply.

Here was the question back in 2006

Phoneman wrote:
"Help me out here guys, audio levels are below clipping and dev set at 2.3k. Got audio from vol/sql high (buffered discriminator) going to the TX flat audio pin in on the GM300. I canot see anywhere on the GM300 that has a TXA printed on it like the Maxtrac. Any ideas will help alot, works perfect with analog and DPL...just not p25. Thanks"

We have the TX GM300 open, no TXA on the board as the Maxtrac has. Where do we insert audio bypassing any filtering on this radio?

Does pin 5 "TX Flat Audio" accomplish this? Was his problem due to incorrect point where audio was inserted or something else?

Thanks!

W1HVN · Post by **W1HVN** » Mon Feb 02, 2009 6:11 pm

Success! We have mated two GM300s with a simple controller to infuse CWID, only after radio unkeys. Hang time is less than 1 sec.

More details to follow!

Coming soon to Durham, CT: Analog/P25 dual mode repeater.

Some extra circuitry had to be implemented, however it does work well.

KE7JFF · Post by **KE7JFF** » Tue Mar 10, 2009 10:11 am

I recently got access to a bunch of Micors and I wonder if I can use the same principal on them for this.

Anyone ever try this wtih Micors out of curiousity?

W1HVN · Post by **W1HVN** » Thu Mar 19, 2009 3:53 am

We have an older Micor for UHF as well, and in theory it should work as long as you can find the points on the rx and exciter to bypass filetering. One word of caution, do some experimenting and see if by bypassing such filtering if you also bypass any limiting as well, if so you may exceed your 5k dev limit in analog. P25 is reported to be 3.5k dev in wide fm with the GM300s.

The repeater in CT has been up and running and has done an exceptional job.

147.1650 (+) with a NAC of 073 or PL of 77.0Hz - Durham, CT

N9LLO · Post by **N9LLO** » Sun Apr 05, 2009 2:58 am

How did you implement the NAC control?

Chris
N9LLO

W1HVN · Post by **W1HVN** » Sun Apr 12, 2009 5:23 pm

Sorry, perhaps it's a bit misleading. The repeater is "open" in CSQ. All of our users use a NAC of 073 or PL 77.0 on the system, however in actuality, any can be used, these are our set standards. The end user unit encodes, decodes and is the "gatekeeper" of what comes through the speaker, the repeater just spits out what it hears. If using analog and a PL, you get a "gated squelch" type product, which is nice. Until someone springs for the Quantar, this is it folks! I'm just a partial owner, another amateur operates the repeater. He is trely the brains and capability behind the repeater.

BTW, the repeater has moved to a new frequency:

It is on 146.415 with an input of 147.415

Still in Durham, CT.

If in the area, check in.

boteman · Post by **boteman** » Fri Apr 17, 2009 11:12 am

KE7JFF wrote:I recently got access to a bunch of Micors and I wonder if I can use the same principal on them for this.

Anyone ever try this wtih Micors out of curiousity?

I have not tried this particular application with Micors, but either a base or mobile UHF Micor would be suitable as they use direct FM of the crystal for modulation. The mobile actually modulates the 11.7 or 16.7 MHz offset oscillator while the base station modulates the channel element. In both cases you would want to bypass the square blue chip that provides audio shaping and limiting. The analog audio when fed this way is schweeeet!

The VHF base station Micor exciter is also direct FM, while the mobile VHF Micor used phase modulation and would not be suitable to this application.

I don't know what waveform shaping is inherent in the recovered signal from the buffered discriminator, but feeding the audio to the exciter this way could certainly splatter so watch your deviation carefully. Others can advise on the proper setting for best performance of both analog voice and digital modes.

***
I have mistakenly programmed a CDM1550 to use the pin 5 "flat audio" input for a generic, run-of-the-mill remote application and regret it. The audio is not filtered nor limited, so while it would be good for this application, it stinks for plain LMR voice because I can't get sufficient punch out of the audio without it splattering.

So pin 5 flat audio for data and transparent audio into the transmitter,

pin 2 for regular old fashioned limited mic audio in.

boteman · Post by **boteman** » Fri Apr 17, 2009 12:26 pm

The Pager Geek wrote:Ok, after much refinement and testing.

Astro Capable Maxtrac Repeater

I converted the above Visio diagram to Adobe PDF. It's about 12KB for your download from my web site.

Astro capable Maxtrac repeater schematic

Digital Capable Repeater using Maxtracs Specs

Digital Capable Repeater using Maxtracs Specs

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