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Galaxy DX99V Talkback Solutions

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  #1  
Old 04-23-2009, 05:07 PM
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Default Galaxy DX99V Talkback Solutions


Problem scenario:
Black Eagle D104 on a Galaxy DX99V. Turn it on. SWR is OK; but how about a little echo to go with this great mic and radio? Turn it on and -WWWOWWW- feedback city! There is no getting rid of it - short of switching the echo off, and there is no adjustment of the volume on the talkback. The talkback and echo are both switched on/off with the same switch.

Solution(s):
*Cut the orange wire and disable the talkback alltogether, as per CBTricks here:
Galaxy Radios DX99V Service Manual

*Or - install a 470MK/ohm resistor as shown on the same page. But this may too much or too little; there is no definite way to know for sure - except with experimenting with the basic 470K/ohm value given.

Question:
*Is it possible to put a 250K/ohm pot in series with a 330K/ohm resistor and make it adjustable with this method?

Anybody ever do anything like this or solved it another way?
All opinion and experience welcome...
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Last edited by Robb; 04-23-2009 at 05:28 PM.


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Old 04-25-2009, 06:31 AM
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There is some information about this problem on cbtricks.com forum. I have a DX99v and I picked up a RF limited model UTB-1 board but have not installed it yet. Galaxy tech stated that this was best way to go with feedback/squeal problem for the 99s and others.

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Old 04-25-2009, 11:16 AM
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try backing the mic gain down on the radio and or the microphonium, bad juju? who knows.

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Old 04-25-2009, 10:56 PM
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If you can put a resistor inline, you can surely put a variable resistor (pot) inline also to make it adjustable.

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Old 04-26-2009, 12:19 AM
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What did I finally do for this problem?
I tried one 470K ohm resistor; not enough.
Then I put two in series - still no dice. Then I put a 1M pot WITH 2 470K ohm resistors in series and it STILL didn't do what I wanted. Looking closer at this resistor mod; it is only good for reducing the distorting on the talk back circuit caused by a radio with more than 100% modulation = 'splatter'. NOT for adjusting the talk back volume.

SO - I put a SPST switch between the green wire at J15. If I want to adjust my echo level and depth, I have to flip the switch on the back so it turns the talk back circuit back on, turn the mic gain down enough (almost all of the way down - BTW), set echo/level, flip the switch back off, and turn up the mic gain.

Anyone have a better way? Fortunately, there was already a factory-made hole in the back of the radio that fit a mini SPST without any difficulty. But Galaxy really should have put an adjustable talk back volume on the radio. It is a pain in the butt to do it the way I did it - but at least I got it to work the way I need it to. I talked to the tech at Galaxy on the phone, and he suggested that I put a ferrite between the internal speaker and the board. I told him that it was audio feedback from too high a level out from the radio, and the sensitive D104/TUP9 just didn't allow me to get enough mic gain out of it to work on the air. He never did answer my email either, nor did his solution solve my dilemma. Mine works; and his didn't. Go figure - this guy must see this problem all of the time from people that have the DX99V and a D104 - and yet they offer no viable solution. I don't like the compromise I had to do to make it work the way it should. But I will keep the radio and keep my solution in place.

My Magnum OmegaForce has a feedback problem with my D104; but it also has a talk back volume to handle it the way that it should. Not knocking Galaxy; but why didn't they see that problem coming off of the drawing board?
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MOBILE: Galaxy DX99V w/RF Limited CR-577 mic, Sirio Z-180. Yaesu FT-8800R & Diamond NR-770.

Last edited by Robb; 05-01-2009 at 01:00 AM.

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Old 04-26-2009, 09:20 AM
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I will have to agree with you about Galaxy drooping the ball On the engineering of the talk back part!

If these radios are at 100% modulation are near they will do that head shaking feed back sequel.
But when running the stock Mic it's OK, but if your going to run a power Mic then your going to have too disconnect the factory talk back. First is your G99v have the new SMT type echo board or is your radio a older model 99v?

# 1 (old type echo board disconnect wire at tr35 this will disable the talk back without loosing echo.
# 2 (New SMT type echo board disconnect wire at j15, this is next r244 this also will give you echo without the talk back.


To have a variable talk back you need to install the UTB-1 talk back board, check out this model at rf limited for more details. This will give you the talk back that your looking for, while retaining the factory echo.

Also if your radio is new this mod may void you 2yr warranty

Last edited by purenrg; 04-26-2009 at 10:01 AM.

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Old 04-28-2009, 03:50 AM
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If nothing else, sell the 99 and get a butt stomping Magnum S9 with variable talk back already there.

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Old 04-28-2009, 04:56 AM
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The 99V should not need an amplified mike. This is what is generating the squeal. You can "dehorn" the mike (bypass the amp in it which works great) or pad the talkback down. Installing a relay talkback circuit will let you fine tune it to where you want.
If you want to use the amplified mike you need to make sure that the gain adjustment is just barely cracked open. You can add a 1K resistor in series with the audio wire of the mike (or experiment with the value) to pad the mike down also.
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