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What if.........you could do astro on 900 MHz?

This forum is for the discussions targeted at converting various models of Motorola equipment to operate in the 900MHz Amateur Band.

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batdude
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What if.........you could do astro on 900 MHz?

Postby batdude » Fri Apr 04, 2008 1:30 pm

do you think there would be many/any takers?

here's the thoughts... the 900 band has long kinda been "unique".

now that the 900 radios from M are in the XTL platform... where this funny little thing called a "DSP" resides...

wouldn't it be pretty neat to operate on 900MHz in P25?



doug
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MTS2000des
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Re: What if.........you could do astro on 900 MHz?

Postby MTS2000des » Sat Apr 05, 2008 6:56 pm

yeah but seriously, 900 is dead, at least around ATL. and what's sad is there are a few repeaters, one on Sweat, a couple on Sawnee mtn, one over at Gwinnett Medical Center. They are quiet 99.9 percent o' the time. And since all the repeater owners want to be little Napoleons and refuse to link their systems together, the coverage sucks ass. the cost of said P25 radios would exceed any real practical value. I'd rather invest in VHF/UHF P25, but then we don't even have a decent 2 meter machine in the Atlanta area on FM. Everyone takes 1.21 gigawatts of ERP to key up from a few miles away...I think I'll stick to HF. I've had better luck talking across the southeast on a ghetto fabulous dipole I built and 20 watts oozing out of an old Icom IC-730 than most of the local machines are coverage wise. Not to mention the topics for discussion...

besides the propagation at 900MHz sucks...not to mention the problems with fading, etc. Not worth it...
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Re: What if.........you could do astro on 900 MHz?

Postby WB6DGN » Sat Apr 05, 2008 10:57 pm

wouldn't it be pretty neat to operate on 900MHz in P25?


NO! I have no interest in spending that kind of money for a RADIO. If I am willing to spend that much money, it will be for TEST EQUIPMENT.
Tom

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batdude
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Re: What if.........you could do astro on 900 MHz?

Postby batdude » Sun Apr 06, 2008 6:17 am

hmmm.


interesting replies.



doug
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Re: What if.........you could do astro on 900 MHz?

Postby xmo » Sun Apr 06, 2008 7:14 am

You have to believe that these new Astro25 based 900 products use the same firmware as all the other bands.

All it would take to test the theory of 900 Astro P25 would be someone who could tweak the flashcode - and there would appear to be some evidence that such can be accomplished.

Hmmm....

-

So, Tom - just what sort of test equipment would that be that you are buying?

I have to warn you - that test equipment thing can get out of hand. For example - lets say I ask you how many oscilloscopes you own. Did you have to take a minute to think about it? If so - you might be a test equipment junkie.

I know I qualify but I guess it is a relatively benign addiction.

Besides, the folks in Washington want us to spend money don't they? After all, they're sending us the stimulus $$$.

Looking at it that way - I am a VERY patriotic guy.

Terry_Glover
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Re: What if.........you could do astro on 900 MHz?

Postby Terry_Glover » Sun Apr 06, 2008 7:37 am

900mhz anything turns me off. From cordless phones to trunked systems, digital or otherwise.

This is just my view on this segment of the RF band, but it seems the most useless piece of spectrum available, except for maybe carefully setup, short point-to-point applications...
Terry

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Re: What if.........you could do astro on 900 MHz?

Postby WB6DGN » Sun Apr 06, 2008 5:18 pm

I have to warn you - that test equipment thing can get out of hand. For example - lets say I ask you how many oscilloscopes you own. Did you have to take a minute to think about it? If so - you might be a test equipment junkie.

I know I qualify but I guess it is a relatively benign addiction.

Besides, the folks in Washington want us to spend money don't they? After all, they're sending us the stimulus $$$.

Looking at it that way - I am a VERY patriotic guy.


Unfortunately, in my case, when it comes to test equipment, I need just about "everything". After working in the industry for many years, I became accustomed to having a nice selection of equipment available without the investment (with permission). Now that I'm retired, I can't get used to the idea that I can't do all of the things that I used to take for granted. A partial "wish list" includes a GOOD (my favorite being the IFR 1900) service monitor, a stand-alone spectrum analyzer, a frequency difference meter for my freq. standard, to name just a few (I'm starting to get depressed!). As for the "stimulus", the only one getting stimulated will be my veterinarian. My old dog badly needs a dental.

900mhz anything turns me off. From cordless phones to trunked systems, digital or otherwise.

This is just my view on this segment of the RF band, but it seems the most useless piece of spectrum available, except for maybe carefully setup, short point-to-point applications...


This has not been my experience with 900Mc in my area. One ham has co-located repeaters on 449Mc and 927Mc (among others) I have compared coverage between those two and have found very little difference between them, if anything, slightly favoring the 900 in coverage and quieting. I realize this is anecdotal as I don't know the relative position of the antennas, etc., etc., but it was a bit of a surprise anyway. I do know that the power of the 449 machine is considerably greater than the 900.

NOW, aren't you sorry you asked???

Tom

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MTS2000des
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Re: What if.........you could do astro on 900 MHz?

Postby MTS2000des » Sun Apr 06, 2008 10:51 pm

well my experience with 900 versus UHF. the BSRG 927.575 repeater is a 100 watt MSF5000 with a 9db gain omni on Sweat Mountain just north of Atlanta in Marietta, from the same site, the NFARL 444.475 repeater operates with an old Stationmaster and a GE Mastr II 100 watt repeater. The coverage is about 1/2 of the UHF. Maybe in Texas where they don't have hills and mountains like we do in North Georgia the UHF and 900 are equal, but around here it plain sucks. The UHF machine in Gwinnett at the hospital is colocated with the 442.85 and 147.075 repeaters, they are all on the same tower- and guess what, the 900 has the least amount of coverage both TX and RX, it too is a 100 watt MSF. No thanks, I still to UHF and VHF...
The views here are my own and do not represent those of anyone else or the company, the boss, his wife, his dog or distant relatives.

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Re: What if.........you could do astro on 900 MHz?

Postby WB6DGN » Mon Apr 07, 2008 12:18 pm

from the same site, the NFARL 444.475 repeater operates with an old Stationmaster and a GE Mastr II 100 watt repeater. The coverage is about 1/2 of the UHF


I'll be the first to agree, that's what you would expect; well, maybe not THAT big a difference, but you would certainly expect the coverage of 440 to exceed 900 just as you would expect 144 to exceed 440 and 50 to exceed 144. Years ago, I remember being told that the big advantage to 450 (this was commercial) was it's ability to penetrate underground parking garages and other like structures better than 150. Again, I think that advantage would manifest itself, maybe to an even greater degree, on 800/900. There's no doubt that 800/900 is not the best choice in hilly/mountainous areas and the sheer numbers of base stations or repeaters required to provide adequate coverage supports this. As an aside, though I have a "5" call, I am presently in the Cleveland, Ohio area and this is where my experience on ham 900 was gained. In summary, while you can't argue with the laws of physics (free space and foliage attenuation happens as do certain other unpleasantries), commercials have been pretty successful in getting around it for some time now and, with the increasing supplies of equipment available to hams, they can too (besides, the fun is in building the equipment, once the site is up and running, the fun is over, IMHO).
Tom

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escomm
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Re: What if.........you could do astro on 900 MHz?

Postby escomm » Mon Apr 07, 2008 4:44 pm

it would be great if you had a group of like-minded individuals who were willing to invest the time in setting up and maintaining the system, but as a whole i don't think there will be much interest. it would be fun to tweak though and see if it were doable though, just to say it's been done.


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