Batboard

Ok , im a bit mistified .. justwhat in the world is hearclear saposed to do?? for you...

Happily programing GTX's .....

KC7NOA

It is a voice compression system.

It is suppose to make the audio more like real speach - with out the frequency - response- roll off you get with the 2.5KC deviation.

Cheezey version of "Companding" (compress then expand).

1motoman wrote:It is a voice compression system.

It is suppose to make the audio more like real speach - with out the frequency - response- roll off you get with the 2.5KC deviation.

So , witch is better ... if hear clear is on .. do both radios need to have it enabled??

and were can some one get adapters .. from the mini-Rf (like whats on the back of the GTX mobile) to a sma (sinclair duplexer)...???

If you have hear clear on, it has to be on for both radio's.

The problem I have run into is using non Motorola radio's on systems that have hear clear enabled - they sound like Sh*t ! , so alot of the times hear clear is not used.

I have seen mini UHF adapters at Radio Shack.

Ditto... in WA we kind of agreed to disable the Hear Clear since there were so many other radio brands in use.

I've had good luck buying adapters from http://www.hdcom.com - click on their "general catalog" icon and choose the kind of adapter you want. You'll probably have to use a piece of coax somewhere as I doubt a single adapter will do what you want or reach the duplexer. Mini-UHF to regular UHF or N or even BNC would be a good way to start, then you can go from one of those to SMA with another adapter if necessary. This same company also will make cables for you with just about anything you want on the ends. LMR-195 coax is a good choice - it's the same size as RG-58 but 100% shielded.

Bob M.

ok .. on the deviation adjustment catagory ..gtx

what is balance attenuator...and deviation attenuator???

Deviation is for Tx deviation of fm .. and balance is Rx ??

Deviation, etc:

If you need to ask, don't play with that stuff. That is all for TX/RX alignment and tuning. You need a service monitor for that and somehow I doubt you have that there if your asking that. Don't mess with it, you'll probably make it worse.


Hear Clear:

Motorola, Kenwood, Vertex, and Icomm all have companding options for narrow band channels. Consequently, none of them are compatible with eachother. This is why it is rarely used in public safety. It would be fine if it was a buisness or something and you had control of every unit used on the system. Motorola named their companding "Hear Clear". Unless you know everyone else on the system uses it, leave it off.

no.. i dont have a service monitor...

but i do have 3 GTX's ... 1 Ht and 2 mobiles ...

the Ht is low on Tx audio ...being heard on the other 2 mobiles....

so that why i ask ....

the balance atteunator is down at 7 ... out of 100(if i remember the top max) on the Ht .. the others are around 60 ...

I've been through the complete alignment of a GTX mobile. I'm sure it's the same for the portable.

The Deviation Balance procedure requires that the unit be capable of transmitting, so you need more than just a 9V battery (which would be enough for programming), plus a dummy load and an audio oscillator. A means of measuring deviation is also required (dev meter or service monitor). The balance "pot" is adjusted by keying the transmitter (F6) and switching between 60 Hz and 2.5 kHz with (I believe) F3. The radio generates these tones, and you want to adjust the pot for the same deviation on both tones, balancing the frequency response. The actual amount of deviation is not important at this step.

The Deviation Adjustment is done next. You provide a 1kHz audio tone via the MIC jack (at least on a mobile that can go through the RIB cable) at quite a healthy level, and adjust the deviation "pot" for the appropriate amount, i.e. 2.5 kHz.

The board replacement procedure is a bit longer as there are 16 different frequencies that deviation is adjusted for. I don't believe there's a balance adjustment for each one, just main deviation.

Some of this is in the GTX help pages. More is in the GTX service manual. I bet there's a full explanation in the GTX RSS manual, which I don't have but would like to obtain.

I've seen/heard three GTX portables, and they ALL had low deviation, peaking around 1.7 kHz. Maybe they sound OK on a truly narrow-band system (i.e. 2.5 kHz) but the local repeater here has a 5 kHz receiver, so I've pushed the deviation up to 2.6 kHz on real loud voice peaks. That makes softer voices at least sound better.

Hope this helps.

Bob M.

yes it does ...

Ill assume that a lower number on the scale means less attenuation .. ie. more deviation...

USUALLY, a lower number, or one to the left side of the scale, means a lower setting. This seems to hold true for main deviation level and power level. As far as the deviation balance is concerned, I don't recall which way made the 60 Hz higher and which way made the 2.5 kHz higher. It would be a good guess that left increases the 60 Hz, but don't hold me to that - I'd have to actually test that out. The center of a range is also a pretty good place to start from, in most cases.

I did find that the frequency warp adjustment seemed to work backwards - moving the slider to the left or to a lower number increased the frequency, which is NOT how it works on 450 MHz MaxTracs and Radiuses.

So the only thing I can accurately say is to move the slider or number in one direction, see what happens on your test equipment, and then adjust it accordingly ! You'll quickly determine the proper direction to correct the parameter you're fiddling with.

Bob M.

My GTX portable is the same way. They were made for narrow band, so the most they want to do is somewhere under 3 kc. What some repeater owners in WA are doing is kinda "split the difference" and have the repeaters set for around 3.5. So the NB radios are a little soft, and the WB radios are a little clipped. Its not the best solution, but is makes things usable for nearly all radios. I like the idea better than just having a repeater that works for Johnson & Kenwood, but Mot sounds crappy. Or vice versa.

PETNRDX wrote:My GTX portable is the same way. They were made for narrow band, so the most they want to do is somewhere under 3 kc. What some repeater owners in WA are doing is kinda "split the difference" and have the repeaters set for around 3.5. So the NB radios are a little soft, and the WB radios are a little clipped. Its not the best solution, but is makes things usable for nearly all radios. I like the idea better than just having a repeater that works for Johnson & Kenwood, but Mot sounds crappy. Or vice versa.

I Belive thats on the West side.. hopefully in a few months .. ill have one up on the east side.... of Washington St.