Sidebar Sidebar
  • You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

Galaxy dx959 mosfet final and driver bias voltage?

Ridgerunner0788,

put a DC voltmeter on the middle leg of either the driver or final while the radio is in receive.
what is that voltage?

now key the mic with the voltmeter connected.
what is that voltage?

it's a place to start.
LC
 
Sorry to get back so late on this on I got the finals from mouser and I put them in but am not getting any whats out of it and am not getting any response on my meters what could be the issue
 
Ridgerunner0788 said:
Sorry to get back so late on this on I got the finals from mouser and I put them in but am not getting any whats out of it and am not getting any response on my meters what could be the issue
Click to expand...

Start with what LC has suggested above your post. Tell us what you’re seeing there.
 
Ridgerunner,

They are trying to get you to look at my last post to you about the driver and final.
a lot of the guys around here know me as LC because that's how i always sign my posts.

we are trying to determine if there is even power getting to your driver and final.
try the test and get back to us. Oh, and do the test in AM mode.
the more detail you provide, the better help you'll get.
LC
 
  • Like
Reactions: TheRealPorkchop
Ridgerunner,

we already know you are not getting any power out of the new mosfets, we are trying to get you to do some testing so we can help pin down the problem.

after reading through the thread again, there are more questions to be answered.

first, why did you replace the original final and driver?
were the originals not working?

next, you said that the lights on the radio were dimming when you keyed up, but you still showed some modulation on your SDR.
is that still the case?

last, do you have a DC voltmeter in order to do the tests i asked about?
LC
 
having a blown driver or final won't necessarily affect your receive.
that is not abnormal.

what is abnormal is spending money to replace parts when you don't know why they went out in the first place.
most likely, whatever took out your originals, also took out your new ones.

you have a bad component or maybe even more than one, and the only way to find it is to troubleshoot.
that is going to require some work from you.

so, report back once you've measured the DC voltages on all the pins on the driver and final, as well as Q54 (the big transistor on the right hand wall learn the power jack) in both RX and TX in AM mode, no modulation.

once you post that info (be specific, tell us which pin reads what voltage and state RX or TX), then we can at least begin to give you some insight on where to look.

If you don't do the testing, there is nothing we can do.
LC
 
  • Like
Reactions: TheRealPorkchop
Yeah if you have a TIP36 laying around or a 754 you can piggyback it on Q54 and see if you see a carrier and swing then. You’ll know that’s your bad part.

Agreed, you gotta trouble shoot it. A voltage chart is a good place to start instead of shotgunning parts at it until you find the bad piece.
 
Ridgerunner0788 said:
Ya I know but throwing parts at it means there all new parts lol
Click to expand...

Good point. Can’t argue that. But you don’t have to replace what’s not broken, they don’t wear down like car parts.

Funny you say that, most guys would take that approach and see it that way yet leave 10-15 year old capacitors in there and not change those.
 

dxChat
Help Users
  • No one is chatting at the moment.
  • @ Wildcat27:
    Hello I have a old school 2950 receives great on all modes and transmits great on AM but no transmit on SSB. Does anyone have any idea?
  • @ BJ radionut:
  • @ ButtFuzz:
    Good evening from Sunny Salem! What’s shaking?
  • dxBot:
    63Sprint has left the room.
  • dxBot:
    kennyjames 0151 has left the room.


      Top Bottom
      Back