galaxy dx 949 low am modulation

[Lil'Yeshua]

Just a thought. If it was me having this problem I would crank VR16 the othr way to see if it made a difference at all.

If it were me I would observe my modulation as I turned VR16 just to make sure it wasn't in no man's land. Is it a good idea to crank it all the way up? DTB had mine set for 100% modulation and VR16 still had travel to go before it reached it's max position.

 

[doc919]

I have tried adjusting vr16 to make sure I am turning it the correct way for max output,but still only showing 4% modulation on am channels. Swing showing 16 or 18 on ssb. I tried pushing down on circuit board for bad solder joints. I have already replaced the AM regulator. Thank you. Any other ideas? Thanks for any n all help.

 

[Robb]

VR-16 is just the AM modulation control; it is not the AM low power or AM high power controls.

VR-18 and VR-14 are the low and high power controls.
Did you mess with them?
If so; then you may have adjusted them wrong.

The low AM power setting should be set with the RF Power output control set at minimum (turned fully counter-clockwise) and then set to VR-18 to 1 watt into a dummy load and no modulation.

The high AM power setting should be set with the RF Power output control set at maximum (turned fully clockwise) and then set to VR-14 to 4 watts into a dummy load and no modulation.

 

[doc919]

Doing just what you suggested is what I have done in that way. I was using the same diagram when setting my high/low deadkey with no modulation as I didn't want it to interfere with any readings.. I will tinker with it some more to see what I can try to figure out. Thanks to all that have tried to help..

 

[Lil'Yeshua]

Doesn't the SSB alc control affect the am modulation to some degree? The Galaxy tech at the time before I had DTB tune it said that I could adjust it with the 'O' on the pot to around 7:30. That is was cranked open. It usually sits at the 10:30 to 11:00 o'clock position.


Note: in AM mode you set the Meter to 'Modulation' for modulation, power for am power and SSB power swing.

 

[Robb]

Doesn't the SSB alc control affect the am modulation to some degree? The Galaxy tech at the time before I had DTB tune it said that I could adjust it with the 'O' on the pot to around 7:30. That is was cranked open. It usually sits at the 10:30 to 11:00 o'clock position.


Note: in AM mode you set the Meter to 'Modulation' for modulation, power for am power and SSB power swing.

Nope; just SSB.
Pot/VR position has nothing to do with how the radio is aligned. Sometimes for the purpose of getting something in the ballpark during a repair a VR may be put in the mid position, like the AM Mod pot for example. But once a radio has been tuned in the shop, don't mess with it or you just wasted your own money.

 

[doc919]

Yes,I checked each of those settings before,other than the ssb setting at 0730. I have even changed out c129 to see if that made a difference. Also just changed the driver & final,just in case. I tried what the other gentleman had suggested about the eraser test to see if there where any weak or damaged solder joints.. Its just got me baffled. Thanks again for all the help.. Guess I will just buy another 1 & compare them with each other n see what comes up. Thanks again...

 

[Lil'Yeshua]

Yes,I checked each of those settings before,other than the ssb setting at 0730. I have even changed out c129 to see if that made a difference. Also just changed the driver & final,just in case. I tried what the other gentleman had suggested about the eraser test to see if there where any weak or damaged solder joints.. Its just got me baffled. Thanks again for all the help.. Guess I will just buy another 1 & compare them with each other n see what comes up. Thanks again...

Or you could send it to a good tech. It may be something simple that won't cost too much or buy a brand new one in the box that DTB will throw in a tune and full alignment and guaranty his work plus you get a two year Galaxy warranty from the time you bought it providing you keep your sales receipt.
If the 949 you presently have is under 26 months old and hasn't been hacked up,Galaxy will fix your radio. Just saying.






Tech Support

 

[doc919]

I would like to thank everyone for all their help & input.. I did a little more/closer look & found there was a solder joint that was touching another solder joint causing a short. Just glad it didn't do any major screwups. Thanks again for all the help.

 

[Lil'Yeshua]

I would like to thank everyone for all their help & input.. I did a little more/closer look & found there was a solder joint that was touching another solder joint causing a short. Just glad it didn't do any major screwups. Thanks again for all the help.

Cool! Could you tell us which ones were touching?

 

[doc919]

On solder side of board,soldier side it would be the left terminal of r264& d107. So on the component side both right side legs were touching just slightly.