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Galaxy Dx 959 Help

J

JDemoret

Member
Mar 5, 2009
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I have the above radio (board # EPT069610Z). Radio was at no TX at all but did get the carrier back but I'm only getting about 50% modulation at 4 watt dead key and it's swinging to about 8 watts. VR 18 (low power) has no effect on dead key and if I adjust VR 14 (high power) to over 6 watts I loose all modulation. VR 16 (AM Modulation) is wide open. Radio is stock with no mods and using a stock mic. Any help would be appreciated. If there is more info needed please let me know.

Thanks John

P.S. I did readjust the bias current to specs in the service manual.
 

Does this radio have bi-polar transistors, or does it have MOSFETs? What does SSB do? Is SSB full output? Let me know on these things, that will help me get you in the right direction. Cheers!
 
The radio does not have the MOSFETS. Modulation on SSB is about 40%. Since the first post I've removed the mod limiter to get about 30% modulation on AM and the 40% on SSB. I would rather not run the radio without the mod limiter if possible.

Thanks John
 
first of all, what did you do to get the TX back and what exactly were the conditions before you got it back?

did it show any output on a wattmeter?
any modulation?
worked on SSB but not on AM?


you might not be getting any adjustment out of VR18 because of where VR14 is set.
you might also have a bad VR18.
remove it from the chassis and test its resistance at different settings.
if its not changing when you turn it to a different point, replace it.

im also thinking that you re tuned the transmit coils in an attempt to get the carrier back.
if you do this and tune for max deadkey, you dont leave any room for modulation and get the results that you are describing.
the trick is to tune the coils while saying "ahhh" into the mic so that you are tuning for max modulated power.

what type of power supply are you using?
how many amps is it rated for?
too low of amperage rating could also cause similar problems to what you are describing.

the more details you give in your response, the more we can help you.
LC
 
Make sure that when you adjust your VR18 that your RF power knob is fully counter clockwise and while adjusting your VR14 the RF power knob is fully clockwise.

Where is your mic gain set?
 
It's been awhile since I've had the radio on the bench but will try my best to provide accurate answers.

The radio was showing no output on the meter on AM with no modulation and sorry but did not check it initially on SSB. There was a damaged trace which I repaired which brought back the AM wattage with low modulation.

VR14 and VR18 were removed and tested......they are good.

I don't recall retuning any of the coils but will check them.

The radio is being powered with a 12 amp power supply.

VR18 was adjusted to 1.5 watt with the RF power knob fully counter clockwise and VR14 was adjusted to 5 watts with the RF power knob fully clockwise...........this I discovered the day after the initial post.

Mic gain is full open.

Thanks John
 
well my guess is that the problem is with whatever part or parts failed and caused the broken trace.

something caused that trace to burn up, and it sounds like you havent addressed that problem yet. repairing the trace is a start, but the cause has not been found yet.

maybe you can show us in this diagram exactly which trace was burnt.
http://www.cbtricks.com/radios/galaxy/dx959/graphics/dx959_ept069610z_trace_layout_bottom.gif

do you know what happened that caused this trace to burn up?
LC
 

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