I have 2 direct injected galaxy 55v's one is mine the others a friends, I had made a 33hml direct inject and used it for awhile for this same friend and when hooked up to his desktop computer the radio acted weird on wattage, he wanted the 55 done the same way so I used it on my setup for a week and worked fine, took it to his house and same thing. When the audio line from the computer is unplugged from the port to c191 the rf power knob can be turned up or down and wattage goes up and down, but with the line plugged in when the wattage is adjusted it doesn't go down unless the key is held down but then tr51 the 2sb827 gets hot and also the pre driver tr46 also gets hot, didn'tmatter my house or his we got the same result other then I'm not hooking my 55 to his computer, I believe it fried something along the audio line where wattage mixes in. I changed the pre driver, all audio amps and regulators and the driver final in the 55 and still no fix, the 33 is now keying almost 30 watts and still no fix. Appreciate the help and info, sorry about the long read but I wanted to get all the info out there I could. If I fix one surely the other is the same but going on the 55 starting out is where I am now.
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Direct injected galaxy DX55V wattage problems
- Thread starter That_guy_in_wv
- Start date
Did you use an isolation transformer or at least DC blocking caps on the audio line?
Which side of c191 are you injecting audio ?
& have you checked his pc has not got any dc on the audio out line
& have you checked his pc has not got any dc on the audio out line
Haven't checked his pc for dc, I have a 10UF cap with the positive in the hole closest to the center of the radio and negative side of cap connected to the line going to the headphone port on the back I put in. My radio has worked fine for the last 3 months no problem with it this way. I do believe his audio outlet from headphones plug on his pc is having some trouble though to be doing this to 2 radios now.
Some PC''s their Single Port Speaker Line-in and Line out - also uses MIC (4 conductor)
It is similar to multimedia Stereo headphones used in todays direct wire smartphone jacks like Samsung's' - so I can see where a "Ultra-High" Audio feedback squeal is occurring - you're seeing the wattage peaking because of it, just you don't hear the "ringing" due to the efforts' frequency range is occurring above/beyond the range of most human hearing.
It is similar to multimedia Stereo headphones used in todays direct wire smartphone jacks like Samsung's' - so I can see where a "Ultra-High" Audio feedback squeal is occurring - you're seeing the wattage peaking because of it, just you don't hear the "ringing" due to the efforts' frequency range is occurring above/beyond the range of most human hearing.
Hello Andy, good hearing from you again. It's a weird problem you can key it and turn the wattage up and try to turn it down without unkeying and the wattage doesn't drop, so what would make the line "short" or "spike" to cause the feedback like this, an open ground or short to ground? I know for sure my buddys computer is the culprit for messing both radio up for sure. I've used the 55 that's done exactly the same as the one not working right for 3 months now with no problems so far.
Where would you start to find what's happened to these radios Handy Andy? I have no scope now the look for noise so I'm a bit under prepared at the moment but have most other test equipment, think I even have a sinad meter here somewhere.
Also the wattage starts out where it does when keyed without the audio line plugged in, but plugged in it will climb slowly in wattage when audio is applied.
Use an isolation transformer on that PC'S audio output. Even if DC is not present, the impedance of the output may be effecting the charge on the cap.
Whoa! 3 posts, and I have just finished on answering just one!
Hmm...Lays potato(e) chips...?
Is his computer a laptop? And does it's audio media (music and Mic) use single port input and output?
Next question...
The radio wouldn't put it out on the air, just internally like a birdie, only self induced squeal. So, it would be harder to see as far as RF goes, but audio wise, you'd know it - try a talkback method like the resistor from ext. SP to PA SP and see what talkback will reveal - because RF is setup with a pass band would be trimmed off, but the damage is being done inside the radio before if's finally trimmed off at the RF TX stage.
This setup in PA mode, would also make the Audio amp in the radio run hot too. So this may be the route to go, find some external speaker and a 16 ohm resistor - put it (resistor) in line IN SERIES with the EXT speaker - so you don't get blasted by the ultra high squeal you may not hear...
Next Question...
Ok, there's the clue I'm cueing you in on. Nothing happens unless that port is connected. So if you're sure you're isolated from the Computer - how are you grounding the output from the computer to shield your radio?
As said in an earlier post - a line isolation transformer can work, but the losses are pretty heavy in the conversion process. You may need to somehow run a wire from your radios case, to the USB "metal shield" used for one of the USB ports as a means to find chassis ground to the PC, unless you know of another way to bond your radio to the PC's ground.
I'm glad to know you didn't just try another radio and wound up taking out two radios in this process, I think the main problem is finding the chassis ground reference for the PC side of things. Its' not always Chassis and 3rd wire plug grounding at the wall either - your issue may be a "floating ground" reference where the PC keeps pumping the voltage to keep the power flowing into the media port - it won't damage it until a breakdown voltage gets exceeded - that can take a while to achieve that. But,, meanwhile, the radio is suffering from the oscillation.
Hmm...Lays potato(e) chips...?
Is his computer a laptop? And does it's audio media (music and Mic) use single port input and output?
Next question...
The radio wouldn't put it out on the air, just internally like a birdie, only self induced squeal. So, it would be harder to see as far as RF goes, but audio wise, you'd know it - try a talkback method like the resistor from ext. SP to PA SP and see what talkback will reveal - because RF is setup with a pass band would be trimmed off, but the damage is being done inside the radio before if's finally trimmed off at the RF TX stage.
This setup in PA mode, would also make the Audio amp in the radio run hot too. So this may be the route to go, find some external speaker and a 16 ohm resistor - put it (resistor) in line IN SERIES with the EXT speaker - so you don't get blasted by the ultra high squeal you may not hear...
Next Question...
Ok, there's the clue I'm cueing you in on. Nothing happens unless that port is connected. So if you're sure you're isolated from the Computer - how are you grounding the output from the computer to shield your radio?
As said in an earlier post - a line isolation transformer can work, but the losses are pretty heavy in the conversion process. You may need to somehow run a wire from your radios case, to the USB "metal shield" used for one of the USB ports as a means to find chassis ground to the PC, unless you know of another way to bond your radio to the PC's ground.
I'm glad to know you didn't just try another radio and wound up taking out two radios in this process, I think the main problem is finding the chassis ground reference for the PC side of things. Its' not always Chassis and 3rd wire plug grounding at the wall either - your issue may be a "floating ground" reference where the PC keeps pumping the voltage to keep the power flowing into the media port - it won't damage it until a breakdown voltage gets exceeded - that can take a while to achieve that. But,, meanwhile, the radio is suffering from the oscillation.
I crossed over the pa/exsp with resister but never heard any frequency noise or squealing from the external speaker. I do hear a buzzing sound on a radio turned on close by hooked up to my base antenna. If I touch the radio it goes away some. But the 55 is on a 100 watt dummy so could just be that why its buzzing on my other radio. My base antenna is on a mountain line 1200 feet away on the mountain top and 400 higher up then where I'm sitting. Not sure it would make buzzing sounds through it if it was closer or not. But I know for sure touching the case or faceplate bezel makes the buzzing noise go away some. When I unplugged the audio cord the noise gets louder when I touch the radio....weird.
I'm using my 55 on the same hp laptop that I'm trying the 55 that is not working right, mine still works this one does not. My buddy uses I believe a dell desktop, his computer is why it stopped working lol. I'll have to see what he wants to do with it. He might upgrade to a newer tower is what he was saying. Again thanks andy and everyone for the help, I'll take any info I can get.
If you don't have a scope switch your watt meter from average to pep. If the average reading is lower there is audio on the carrier or an oscillation problem.