Northern California 900 Repeater System
How to get on the 900 Amateur band.
Until recently, there were never any amateur transceivers built for the 900 Amateur band.  Alinco has the 900/220 HT avail and they work great!  The only mobile radios out there are commercial radios that can be converted to operate in the Amateur portion of the band.  The commercial 900 band is just above and just below the 902-928 Amateur band.
This will give a brief description of what's out there and how much effort is needed to convert the radios for use in the Amateur portion of the band.
First, we'll start with Motorola


This is the smallest radio and easiest to get on the band.  It is NOT the cheapest but is the smallest of the Motorola 900 radios.  They are 10ch, but are easily converted to 15ch via software, but the radios display for ch 11-15 is not correct and just strange characters. The radio still works fine on the expanded channels.  The 30W UNITS REQUIRE NO MODIFICATIONS for the HAM bands!  The only modification is the power output on the 12W units.  The TX power is unstable on the Amateur frequencies.  They will usually go to full unregulated power, about 19W or 0.8W with no rhyme or reason as to why.  There is a mod to fix this on I will be mentioning this site NUMEROUS times on this page.  It is a great site!  There is another problem with the GTX when programmed with a lot of HAM channels, the deviation on SIMPLEX is very low.  Internal adjustments do not help.  It's a software issue just like the power control.  Just something you have to live with.  Not sure if the 30W models have the same problem, but since the power is not affected on the 30W radios, I assume the dev isn't either.
There are numerous variations of the GTX like the LCS 2000 and the GTX LTR.  These are all just glorified GTX's.  Some with more channels and features.  Unfortunately, GTX's have doubled in price on ebay in the last year.  I still don't know why as they are the lowest quality of the Motorola's in my opinion.  They go for around $100-$120.  They come in 12W and 30W versions, but the 30W GTX's are rare.  NOTE:  The GTX was ONLY avail in 800 & 900 MHz.  The 900 units model number begins with M11W.  The 800MHz unit is M11U.  The heatsink on the 30W radio is considerably larger.  The user's manual can be found HERE.


For those of you with Maxtracs converted from trunking radios, your panel is probably not correct.  Below is an illustration of what the buttons on your panel "really" do.

This is a very simple radio and inexpensive.  Much better quality than the GTX in my opinion.  They come in 12W and 30W versions and either 2 or 16ch.  The 2 ch radios can be easily converted to 16ch radios by a technician with the proper software.  The problem with the maxtrac's is that they require some "in depth" modifications.  They need the VCO modified and the front end filters bypassed, retuned or replaced.  The filters are getting hard to get these days.  All the info can again be found at  The Maxtrac is the ONLY radio that can be converted to both RX and TX the entire 902-928 band!  This means repeater "reverse" input monitoring, use as a repeater receiver or just a test radio.  The modification to do this is much more extensive than the standard "ham" mod, but it is nice to always have one around.  Unconverted Maxtrac's usually go for around $20-50.  Modified with filters can get up close to $100.  The MAXTRAC user's manual can be found HERE.


The spectra is a very high quality, "emergency service" police style radio with tons of extra features!  Spectra's have features like remote head capabilities, simplex on any repeater channel with the touch of a button, front panel selectable PL tones, scan, RSSI readout, 8 digit alphanumeric display, DTMF.
They are easily modified for the Amateur band by simply adding a resistor on the VCO.  No other mods necessary, BUT, most older spectra's, aside from the Spectra II, need the electrolytic caps changed out as they go bad and leak. This is also described here at repeater-builder.  They range in price from $25 for well used. dirty units to $120+ for cleaned up and modified radios with all the accessories.  They come in MANY variations of available features, so be aware of what you want before buying a spectra.  They are a little more complicated to use and program than other Motorola mobile radios.  Some may only be capable of ONE conventional channel while another may be capable of 128 channels and all features and they BOTH will look identical!  We'll start with the best!  The "Spectra II" or what we call the "E" series Spectra's.  They don't look any different than a regular Spectra, but they all have all features and 128ch's.  The only way to tell is the model ID#.  Below is a list of various Spectra model #'s.  Most all Motorola 900 mobile radios are "trunking" radios, but that doesn't really matter as most trunking radios have conventional channels. 
Here is a short breakdown of model ID's
D37 KGA 5J B 7 F K
D37=30W (D27=12W) I have seen D17 units, they are 3W radios.
KGA is a trunking radio (KMA=Conventional only ...rare).
5J is insignificant.
B=anything other than "A" means some sort of trunking radio. "E" is the best! 
7 is the style of faceplate or control head.  7=full 12 digit DTMF head, 5= three button head, but doesn't really matter as you can change them in software to be either. 
F=version.  Anything before F is questionable.  See below. 
K is insignificant.
Here are some model's to look for.  Also, any spectra with a BLACK model and ser# tag is a newer unit!!
D37KGA5JE7AK=Spectra II.  As long as it is an E7, the rest doesn't matter.  Buy it!  They run around $100.  More if they have the separated control head and cable for trunk mounting.
D37KGA5JB7FK or JB5FK.  These are usually OK for 128ch IF the 5th digit of the ser# is an R or later.  Anything earlier than an R may only be 10ch.
D37KMA7JA5AK= The rare conventional only spectra.  Even the lowest model will have 32ch, but may not have many other features like MPL(front panel PL select) or DIR (simplex on any channel).
It all boils down to the firmware that is in the radio.  You can check this by powering on the radio, as soon as you see "SELF CHK" on the screen, press the HOME button FIVE times very fast, then press the MODE up button once.  The display should read "VER  523" for ver 5.23.  5.23 or higher is good for 128ch and most features on a KGA radio.  On a KMA radio, ver 1.00 will have 32ch and no fancy features, 2.13 will usually have 128ch but not many features, 6.16 and up will have all features.  BEWARE!!!  I have bought early KMA radios that were upgraded to KGA radios with only ONE conventional channel!  Don't always believe the model tag!  The Spectra User's Manual can be found HERE.

Other "newer" 900 Radios

There are newer radios out there, but they get pretty expensive.  The Motorola MCS2000 is one of the newer models.  There is a Model 1,2 & 3.  Model 1 radios resemble a GTX, but have an 8 digit alphanumeric display and other features like the Spectra. They are are 48ch.  The model 2 & 3 radios have numerous buttons for a ton of features and are usually 160 or 240 ch and have a 14 digit alphanumeric display.  All models come in both 12W and 30W versions.  Most don't need any conversion BUT about 1 out of 20 MCS's require a VCO adjustment for the 900 HAM band, and this is a very tricky modification to do!  Unless you are good at SMD and microwave style strip line tuning, don't try it!  Info on this mod can be found here.  Model 1's usually go for under $200 and the 2 & 3's can reach $300, but good deals do happen!  The Model 2 & 3 can be remote mounted. 
ALL the MCS radios can be programmed with a newer Windows based computer.  No old boat anchor computers needed to program these!  They do require a RIB, but they are avail on ebay for around $15.  You can make your own cables. 
The MCS's come in all bands, the 900 models model ID number will begin with M01WGxxxx for 15W models and M01WJxxxx for 30W models.  The "W" designates the band as 900 and the G or J designates power level. 


There are many HT's out there, but they usually cost more than a mobile radio.  The GTX HT and MTS/MTX series are very common and very nice radios running around $120+ with all accys.

Programming Motorola Radios

Unfortunately, programming Motorola radios requires Motorola's software, and they are VIGILANT on protecting it!  There are many radio techs out there like myself with licensed Motorola software that are willing to help you set up and program your radios for you.

Kenwood, Johnson etc.

Kenwood and Johnson make 900 radios and they are nice radios, but some radios don't do odd splits like the Motorola's will and I don't think the Kenwood's are higher power than 15W.  I don't have much info on them.  The Johnsons require a firmware change to make them work.  More info HERE.  I do know that there are programs out there to get the Kenwoods to do odd splits, but programming requires some tricks.  There are many people out there that can help with this on the 900 reflectors.  Here is a link to a program for programming HAM channels in the Kenwood radios.

More info on many other 900 commercial radios can be found here.

Differences between Kenwood 981 and Motorola radios

First of all, the only Kenwood you want for a mobile or base is the TK981.  The 931 & 941 are difficult to program for HAM repeater splits and a pain to use.
The Kenwoods are smaller, "cuter" and if you ask a Kenwood fan, "the best 900 radio on the planet".
BUT...Here's what you really need to know.  The TK981 is a 15W radio.  There was never a 30W 981 built.  They can be modified for 30W if you want to spend the money for the PA and take the time for that 3db.  The 981 is a very nice little radio and software programming materials are much easier to get your hands on than Motorola stuff.  The only radio you can really compare the Kenwood to is the Motorola Spectra or MCS2000.  The Kenwood has an alphanumeric display like the other two, but the Moto's are both avail in 30W models.  The KW has more channels avail than the Spectra, but the MCS2000 is avail with 250ch.  The biggest difference, other than size, is the scanning functions of the KW vs MOTO.  The kenwood has 32 "Systems", similar to a "Zone" on a MOTO,        and you have "groups", similar to a "mode" in moto.  In a Motorola, you can have up to 128ch (spectra) in one zone (or no zones) and scanning is dependent on what channel you are on.  You can program the radio to scan up to 16 channels out of the 128, dependent on the channel SCAN LIST for that channel you are on.  In other words, EVERY channel has it's own scan list, so if you change channels from let's say Sacramento, where you have it programmed to scan only SAC channels, and you drive into the Bay Area and change to the Oakland machine, your radio will now scan Bay Area channels automatically as you have them programmed into the scan list for that channel.  You can have a specific scan list for EVERY channel in the radio!  The drawback is that you can only have 16 ch's in any scan list, so if you want to scan more than 16 channels at a time, you cannot.  When a Moto is set up for ZONES, it is entirely different.  There is a scan list for each zone, but it works the same.  The MOTO also has what's called "Nuisance Channel Delete".  This is one button which will temporarily delete any channel from the scan list....great for ratchetjaws!  The KW has this also, BUT the scan function is entirely different!  In a KW, EVERY channel that you put into one "SYSTEM" will be automatically scanned...even if you don't want the radio to scan at all!  You CANNOT turn off the scan function built into each system!!  It's ALWAYS ON!!  The only way to do it is to tell the radio to "SKIP" each channel you don't want scanned in a system so it doesn't scan them.        This is done in the programming and is not changeable from the panel.  The only way to avert this is to program only one channel into each system, then the SCAN button will act like a normal SCAN function and you can use the "Nuisance delete" will only have 32 channels avail to have that kind of control of.  If you are NOT a big fan of scanning, this is a good choice, but be careful programming because it will ALWAYS be trying to scan EVERY channel in a SYSTEM.  ALSO...the "one button simplex" found on the Spectra and MCS is a later added option on some of the Kenwoods.  The Spectra also has a signal strength display.  I'm not sure if the KW can do this. 
SO...weigh the plus and minus of each and decide for yourself!  KW people absolutely love them!  I had a couple, but couldn't deal with the scanning functions.  It just wouldn't suit my needs.  They are small and nice radios!  Spectra's are older and bigger, and MCS's are very new and expensive!  You decide!

The EF Johnson 5100 HT!

This is a great little HT!  They have front panel frequency entry, PL,DPL,NAC, Power HI/LO and simplex control!! They also have a full 16 digit DTMF pad and do P25 Digital!  A few P25 repeaters out here now!  Also has a 10 digit Alphanumeric display!  I finally got talked into one of these (they had to give it to me!) and was very impressed!  Still not sure how many channels it has, but well over 100!  Software is readily available and you don't need an old computer to program!


There are many manufacturers of antennas for mobile 900 systems like Larsen, Antenna Specialists, Comet etc.  Get at least a 3dbd (5dbi) antenna and there are 5dbd mobile antennas avail also.  The 3dbd antennas have one coil and the 5dbd antennas have TWO coils.   You can also use old 850 cellular antennas and cut about 3/4" off the bottom and they will work pretty well.   You may want to try to run something like RG8X or LMR-240 for 900 mobile as the loss on RG58 is pretty high!

For base antennas, you can keep your eyes out for a surplus paging antenna.  Just look at the freq.  Most are 890-960, but some are narrow band like 931-938!  Beware of these.  Believe it or not, Comet actually makes a very nice 900 base antenna!  The KP-20.  It is 7' tall and has over 9bdi gain!  They work very well!  Click HERE to see the datasheet.  HRO carries them for around $90.

  If at all possible, avoid using adapters for the "mini UHF" connector on the back of the radio.  An actual mini UHF connector for LMR-240/RG8X or RG58 is cheaper than the adapter!

If you are interested in acquiring a 900 radio, sign up for the NC9RS yahoo reflector HERE.  I keep a close eye on Ebay and when there is a good deal, or if someone else has radios for sale, I will post them on the reflector.

Model 1
Model 2
Model 3
A Kenwood TK-981 next to a Motorola GTX for size comparison.  Note the Kenwood is smaller and has an alphanumeric display.  It also has a large channel capacity and other nice features.  They only come in 15W models. They can also be easily programmed with a modern Windows computer and software is easily found.  They are tricky to program on the 900 HAM band, but once you're used to it, It's easy!  The 981 does odd splits easy!
Quick Setup Tips for the Alinco DJ-G29 on 900!

This new little HT is the first and only HT built for the Amateur 900 MHz band!

Here are a few quick tips for things like odd offsets and bandwidth!

First, the DJ-G29 defaults to WIDE FM!  This is rarely used on 900!  If the display says "FM". it is in WIDE mode!  It must say "NFM" for Narrow FM!  This is changed by pressing FUNC then the MODE button (4).

Next, the ODD OFFSET, that most of the NC9RS repeaters have and many others too!
In the VFO mode, dial up the RX freq.  For example, 927.6375.
Now, figure out your offset.  Subtract the desired TX freq from the RX freq..
927.6375 - 902.0125 = 25.625
Now set the radio to NOT use auto offsets!
FUNC -> then press the top knob and then press the MONI button on the side to make sure you are in the top menu of the "Set Mode", then turn the top knob until the display says "Repeater".
Now press the top button again and set to "Auto Rpt Set" OFF.
Press the MONI button then FUNC to exit.
You are now out of the auto offset mode.
NOW,Press FUNC then MAIN and the SHIFT setting is displayed.
Set to the offset you calculated above, 25.6250, and make sure it is in "-",
then FUNC to exit and you can now save the freq with the odd offset to memory!
Just an FYI, the book calls it "Register A Memory", you and I call it "VFO to Memory"

Something else to activate is the "TX Delay"
This is equivalent to Motorola "Reverse Burst", but is what many call "Chicken Burst."
What it does is when you let up on the PTT, it will transmit for a few hundred milliseconds with NO PL.  This will usually stop the "SCRRRRRSCH" sometimes heard on repeaters.
The best setting I have found is 0.3.
Go to the Set Mode by pressing FUNC -> then push the top knob then the MONI button on the side.
Rotate to "Transmitter," then push the knob again, rotate to "PTT Delay", then rotate the outer ring on top until it says 0.3.  Now MONI then FUNC to escape! 
Be sure to make all these settings BEFORE you save to memory!

I would HIGHLY recommend getting the free programming software!
The only expense is the programming cable.  It uses the same cable as the Yaesu VX6-R, BUT...the Alinco has a programming rate of 57,600 that cannot be changed and many of the cheap Chinese cables will NOT work at that speed!  I have a VX6-R cable by Yaesu, the ADMS-VX6 and it works fine.
The software is called "G29 Clone Utilities" and works great!  Makes programming extremely easy!  You can also assign the knobs on the top to different functions and locations making it easier to use!

Here are a couple screen shots of the software.

DJ-G29 Programming Tips at Bottom Of Page!