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Author Topic: 900mhz dieing!???  (Read 1236 times)
KG4CJV
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« on: August 01, 2000, 09:23:42 PM »

I was just looking at my portable phones manual and it says it operates right on the ham band of 900mhz!!!! I dont know whats going on but it sounds like 900mhz is being taken over by portable phones. If I get a tranceiver and it operates on 900mhz I would not tolerate portable phones!
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« Reply #1 on: August 02, 2000, 11:39:20 AM »

I haven't seen any amateur transcievers for the 900mhz band. It would appear that the only way to use it is to build your own equipment, probably using the same parts that went into that cordless phone plus a larger power amplifier (idea?)

I noticed the same thing myself, actually. I borrowed a frequency counter and tested the cordless phone and it does indeed transmit on 926MHz or so which is near the top of the 900MHz band.


Does anyone know why there is almost no 900MHz amateur equipment available?
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WF0H
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« Reply #2 on: August 08, 2000, 08:59:38 PM »

The last time I looked,  there was a company selling pre-assembled transmitter/exciter boards and kit receivers for this band.  I want to say VHF Engineering, but I think that was the name of their predecessor. The boards are not cheap.  The 902 Mhz. band is not a world-wide amateur band, so , like 222 Mhz.,  the manufacturers have a very limited market for any equipment they produce.  I doubt that anybody has ever made any real money on 222 Mhz gear in this country - what a pity, the band is every bit as good as two meters with somewhat different propagation.  
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WB6QZL
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« Reply #3 on: August 10, 2000, 02:12:14 PM »

Metricom has plans for their wireless internet for all
major US cities.  If you happen to be within range of
one of their poletop radios as I am,  you will hear lots
of clicking on a narrow band 900 MHz radio.  This includes
my 900 MHz spread spectrum cordless phone.

Also, the 2400-2483 MHz spectrum is to be used so more
interferance can be expected on this band also.

An antenna connected to a spectrum analyzer shows lots of
activity here in the San Francisco bay area on 902 to 928
MHz.

Maybe if you live in a major city,  you might think twice
before spending money on a 900 MHz radio.  

For more information on the Metricom radios,  goto
www.metricom.com/ricochet_advantage/tech_overview/radio_
specs.html.

73 Jim

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KD5LWU
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« Reply #4 on: October 15, 2000, 11:14:28 PM »

I agree that we need to protect our freq's by using them. I have set up a 900Mhz ATV at my QTH. It is low power and am looking for an RF amplifier so if anyone has an ideal, or knows where to find a cheap one, or kit, let me know by email or 505-334-0440 thanks
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KD5LWU
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« Reply #5 on: October 15, 2000, 11:15:09 PM »

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KB9CFH
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« Reply #6 on: October 18, 2000, 09:08:00 PM »

If you check some of the security systems, most of their transcievers operate in the 900 Mhz area. Inovonics is all spread spectrum at 900 Mhz and a lot of short range video is up there too. Just about everything I do at work involves some kind of spread spectrum operation at 900 Mhz.
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W9JCM
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« Reply #7 on: October 27, 2000, 05:12:51 PM »

Yes it is dieing. Its to bad too. I have asked many hams in my area about it and they take no interest. I think 900 is awsome for around town. The ant. are small and you can make a awesome yagi. But i can find any equip either.  I thought there was some commercial motorla or something of that sort that would be able to be used for it. Hell or even hand helds.
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KG4FTA
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« Reply #8 on: November 01, 2000, 03:51:01 PM »

Most of the equipment available for this band are transverters from 2 meters or 440.
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N6MAI
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« Reply #9 on: November 07, 2000, 04:04:01 PM »

Well, it *IS* a real ham's band. You have to work for it if you want to be on this band. KB6SJT, Jon Schwarz (sp?) is great at converting 900 mhz Motorola Radius/Maxtracs to that band. A filter in the receiver needs to be swapped, too. He has a nice system up using those radios as a repeater. Also, if I remember correctly, we are not primary on 900 mhz, so expect the worst as far as garbage interference issues go.
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NI6G
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« Reply #10 on: November 08, 2000, 09:57:10 AM »

I regularly make 200 km SSB/CW QSOs on 902 MHz during the ARRL VHF Contests using an SSB Electronic LT-33 transverter at 5 and-a-half watts with an 18 element M2 yagi. In the San Joaquin Valley of California, the noise floor isn't bad at all.  I assume the noise floor is much worse in the San Franciso Bay Area and LA Basin from spreadspectrum LAN stuff. However, since highly directional antennas are easily available for this band, that problem can be overcome. Every once in awhile we have QRM from cordless phones in the San Joaquin Valley. Sometimes they end up right on 902.100. So, we just work around them by doing liason work on 2 meters or 70 centimeters and QSY'ing. The only drawback of this band is the low level of activity. I think Joe Lynch N6CL of CQ Magazine did us all a great disservice by refering to 902 MHz as "the garbage band of ham radio" in a recent column of his. He had similar comments about 2.3/2.4 GHz. Negative comments like that are almost like saying, "Here PCS, LAN, ISM guys...You can have it!" Anyway, don't write off 902 MHz. It sometimes propagates better than 1296 MHz. Check out Down East Microwave or SSB Electronic USA. Oh yeah, you can reprogram some Kenwood and Motorola landmobile rigs to work 902 FM. If you want a repeater with fewer users than 2 meters, 902 is the place to be. HI. So, there's something there for everyone: SSB/CW/FM/ATV...you name it. Maybe some group should form an RTTY AutoStart net...or how about some Helleschrieber QSO's on 902? hahahahah
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WA9YOZ
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« Reply #11 on: November 14, 2000, 09:06:43 PM »

I thought one could convert a "Rabbit" wireless TV sender on 900MHZ?..I just might do it someday!
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OH3BK
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« Reply #12 on: March 01, 2001, 04:15:16 PM »

Funny...here in Europe we have loads of surplus 900 MHz analog cellphones. We don't have the 33 cm band so we convert them to 23 cm.

See our pages at

http://oh3tr.ele.tut.fi/english/modifications.html

for some ideas in converting cellphones and trunking radios for ham radio use. It only needs the service manual and a person familiar with the microprocessor used to write a completely new ham radio software for any equipment.

I think converting 800 MHz AMPS phones to 33 cm FM rigs should be relatively easy, too. Just like we convert the European 450 MHz cellphones to our 432-438 MHz 70 cm band.

73 de Benjamin OH3BK

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KC5JK
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« Reply #13 on: March 09, 2002, 01:56:19 PM »

Yes, it is a shame that we are squandering a great new band due to lack of interest and apparent lack of ready-to-use equipment.
What the so-called ham "leadership," including clubs, magazines and others are failing to tell the fraternity is that Japanese CBers are already way ahead of us on SHF.  They've got the ultimate CB, which addresses and solves every problem the FCC gave up on here.  ATIS (auto transmit ID), 180 trunked channels (auto QSY off the call channel to a clear talk channel, and again as needed to avoid QRM), SHF eliminates skip, FM eliminates heterodynes...  You name it, they've done it.
What's more, every Japanese ham manufacturer, as well as stereo makers and others, build this gear.  Kenwood wanted to introduce a version of the JPRCS chassis as a modern high-tech 902MHz ham rig, except that SCRBBA (the 902 band coordinating committee in L.A.) refused to let their representative (or any of us "outsiders") into their closed-door session, where they secretly devised an irrelevant band plan suitable only to their elite ATV special interest members.
So Kenwood applied some of the JPRCS technology to simplex/duplex radios on other ham bands (examples, TM2530, TM3530 etc).  Few of us took notice.  Unlike CBers in Japan, American hams just aren't ready for it yet.
So, fifteen years after we got our new WARC band, we are still on our own.  The JPRCS channels my Sansui trunked rig operates on are within the W4 band plan published openly in 73 many years ago.  NCG Company of Anaheim, Ca also introduced a simplex rig that works on these channels, but the trunking concept is what hams really need to warm up to on this band.
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W7BAS
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« Reply #14 on: March 15, 2002, 10:52:54 PM »

There IS plenty of equipment that is easy to make work on 902. Try the Kenwood TK-431. Freeware software ont the net, and a $30 cable to program it and you are ready to go.

There is PLENTY OF GEAR FOR 902. Just use it.

P.S. I recently seen a set of 15 Kenwood TK-431's on e-bay go for under $300 for all of them.

Bruce W7BAS
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