P25 Repeater...."poor man's"........

This forum is dedicated to discussions pertaining specifically to the Motorola ASTRO line of radios (those that use VSELP/IMBE/AMBE), including using digital modulation, digital programming, FlashPort upgrades, etc. If you have general questions please use the General or Programming forums.

Moderator: Queue Moderator

Post Reply
User avatar
nickjc
Posts: 233
Joined: Mon Oct 28, 2002 5:31 pm

P25 Repeater...."poor man's"........

Post by nickjc »

This MAY have been covered before but I find no link with the search function.

A group of guys in the Northwest section of NJ are interested in upgrading our MSR2k UHF repeater to a mixed mode Analog/P25 Machine.....I told them to stay away rom Moto equipment..I warned them ! :wink: now they are overboard!

So it is time to really start searching in interest for this project....I have been elected.....any ideas or thoughts..??? Sarcasm is always enjoyed... 8)

Regards,

Nick
Regards,

NickJC

Image
Top
User avatar
FMROB
Posts: 1002
Joined: Sun Jan 12, 2003 2:28 pm

Post by FMROB »

Huh?

Msr2000...
Top
User avatar
batdude
Personal aide to Mr. Cook
Posts: 2741
Joined: Thu Oct 04, 2001 4:00 pm

..

Post by batdude »

brocomm has VHF low split quantars on ebay for under $3000.


A STEAL



doug
BRAVO MIKE JULIET ALPHA
"You can do whatever you want, there are just consequences..."
IF SOMEONE PM'S YOU - HAVE THE COURTESY TO REPLY.
Top
User avatar
wavetar
Administrator
Posts: 7341
Joined: Sun Sep 09, 2001 4:00 pm

Post by wavetar »

FMROB wrote:Huh?

Msr2000...
Yes, MSR2000...mid-tier Motorola crystallized base station / repeater offering for many years. Quite popular for conventional systems, never made available for trunking though.

I haven't heard of anyone attempting to modify an MSR for P25 use, there certainly hasn't been any information posted here if anyone has been trying it.

I think it's possible to do, you'd need to take the most direct route possible between the discriminator output & exciter input...skip over anything that might be in-between, except maybe a level adjustment in order to get the proper deviation on the output. If it does happen to run through some sort of buffer circuit before you can access it, be aware it may invert the data...let it run through a second one if this is the case.

With some luck, you may succeed.

Todd
No trees were harmed in the posting of this message...however an extraordinarily large number of electrons were horribly inconvenienced.

Welcome to the /\/\achine.
Top
User avatar
nickjc
Posts: 233
Joined: Mon Oct 28, 2002 5:31 pm

Repeater

Post by nickjc »

Sorry Gents....

My post in retrospect is misleading...I was just stating we happen to have a VHF msr2k...

My question is what is the best possible route for a UHF PS25 machine...I was in know way thinking of upgrading the msr to p25....

BUT it is interesting to see that there are some available at *reasonable* price points...

anyone know of a UHF model in that range??

nick
Regards,

NickJC

Image
Top
User avatar
batdude
Personal aide to Mr. Cook
Posts: 2741
Joined: Thu Oct 04, 2001 4:00 pm

...

Post by batdude »

some of the uhf's on ebay have gone that cheap.

it just depends.


some of jeff cherry's 110w quantro stations (these use MSF PA's) have gone in the mid- 4500 range.

still not bad for a $12k (stripped) repeater from moto.



doug
BRAVO MIKE JULIET ALPHA
"You can do whatever you want, there are just consequences..."
IF SOMEONE PM'S YOU - HAVE THE COURTESY TO REPLY.
Top
User avatar
nickjc
Posts: 233
Joined: Mon Oct 28, 2002 5:31 pm

yeah but

Post by nickjc »

C'mon there *HAS * to be an easier way...I mean really.....no fancy bells and whistles....

still 4500 is hell of alit of coin for a machine.....but if that is what they get....

i still think there has to be an easier way.....

:o
Regards,

NickJC

Image
Top
willbartlett
Batboard $upporter
Posts: 459
Joined: Sun Sep 16, 2001 4:00 pm

Post by willbartlett »

we are going to try this near Boston with some 1/4Kw ex-paging micors we got for free (can't get any cheaper than that) from a paging co. We know they will tx 4 level (flex), we just need to figure outy how to strip off the incoming signal and reproduce it with sufficient fidelity. We do have the benefit of having a guy working on it who used to service securenet stuff for the government. I know, cheap hamster tricks, but hey, we're all bored with our jobs, so why not. :D

Will
Top
User avatar
Bob
Posts: 1006
Joined: Wed Sep 05, 2001 4:00 pm

Post by Bob »

You could put a couple maxtracs together. If done the right way, you can get them to pass pretty much anything.
Top
User avatar
nickjc
Posts: 233
Joined: Mon Oct 28, 2002 5:31 pm

Post by nickjc »

If that is the case.....what is the right way.... 8)
Regards,

NickJC

Image
Top
ASTROMODAT
Posts: 1825
Joined: Tue Nov 05, 2002 12:32 am

Post by ASTROMODAT »

Enuf already of the MP5---paleeze!
Top
User avatar
KG6EAQ
Batboard $upporter
Posts: 1862
Joined: Mon Jan 14, 2002 4:00 pm

Post by KG6EAQ »

ASTROMODAT wrote:Enuf already of the MP5---paleeze!
Hahha I AdBlocked it the first time I saw it.
-Robert F.
KG6EAQ
Top
User avatar
nickjc
Posts: 233
Joined: Mon Oct 28, 2002 5:31 pm

Post by nickjc »

??....Happy Now....??

:-?
Regards,

NickJC

Image
Top
User avatar
Bob
Posts: 1006
Joined: Wed Sep 05, 2001 4:00 pm

Post by Bob »

I haven't seen the actual mods, but I have seen it work. I would suggest starting by looking at the 9600 Baud mods. Remember, the maxtracs are good radios for passing data.
Top
User avatar
nickjc
Posts: 233
Joined: Mon Oct 28, 2002 5:31 pm

data

Post by nickjc »

Hi Bob...funny you shsould mention that.......I had used some maxtracs in the past to pass 2400bd data via TNC's etc.....

Without me seraching (lazy sorry :wink: ) do you have a thread link to 9600bd mods??

thanks

Nick
Regards,

NickJC

Image
Top
User avatar
FMROB
Posts: 1002
Joined: Sun Jan 12, 2003 2:28 pm

Post by FMROB »

Sorry, I was originally confused by the first post as well.
Top
User avatar
Bob
Posts: 1006
Joined: Wed Sep 05, 2001 4:00 pm

Post by Bob »

Check the maxtrac model-specific section on batlabs.com. I believe it tells you there what mods need to be made to run the radio at 9600.

http://www.batlabs.com/maxrad.html
Top
User avatar
Astro Spectra
Posts: 669
Joined: Sat Sep 22, 2001 4:00 pm

Post by Astro Spectra »

Perhaps I may be of inspiration? I have a MSR 2000 operating just fine in Astro CAI mode … well actually any FSK signal. The MSR 2000 transmitter works very well as the modulation is easily direct coupled to the varicap in the TX element so you can have essentially a TX frequency response down to DC. As wavetar suggested it is best to couple directly from discriminator.

I cut the RX and TX housing completely away from the control section using a band saw. You need to clean the edge of the RX/TX PCB backplane with a file to make certain there are no shorts. Wiring is point to point on the pack of the feed thru pins that connect to RX/TX modules. As a simple Astro mode repeater you don't need all that AC/DC remote control stuff. And all those darn links just get in the way.

A couple of points: the system I did is Astro/FSK only and unlike the Quantar there is no proper adaptive FSK slicer, equalization, error correction, element re-timing or re-framing. So it is a poor man's system and does not work nearly as well as a Qunatar on weak signals. Given time I'm planning on a slicer and PLL to improve the weak signal side of things.

The MSR manual is a must, plus a decent modulation meter (I'm spoilt with an HP8901B).

I’ll post a picture if I can figure out how.
Top
Post Reply

Return to “Legacy Batboard Motorola ASTRO (VSELP/IMBE/AMBE) Equipment Forum”