Shadetree Mechanic
Delaware Base Station 808
I made a comment on the video and asked him if he had to adjust the bias on the RFX, he said no. So I guess the bias may, or may not need adjustment. If it sounds ok then it's good to go.
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Palomar RFX95HD
- Thread starter grimace
- Start date
I made a comment on the video and asked him if he had to adjust the bias on the RFX, he said no. So I guess the bias may, or may not need adjustment. If it sounds ok then it's good to go.
I think he only had to adjust the bias and ALC on sideband. AM was no problem.
I think Chris was referring to the rfx bias adjustment.
I wondered the same thing.
Shadetree Mechanic
Delaware Base Station 808
Quick update: Yesterday I pulled the Lincoln 2+ out of my truck and put the 86v in. While sitting in my mother in laws driveway, I made contact with 605 Texas on ch36 lsb. He reported that I was 20 over and sounded great. He asked what I was talking on, so it seems that the Galaxy lives up to it's big audio reputation. It might be a while before the X9 makes it into the truck......
That's great man, seems like that 86 is pretty stable too. Good to see a galaxy kicking the cat and walkie the dog.
Care to share you method of setting that rfx bias?
I may see how one fits the Texas ranger 797.
Shadetree Mechanic
Delaware Base Station 808
This is how I did it, someone let me know if I missed anything.
Ok, in a nutshell. Basically it's what you would do to set the bias on a radio that has no mirror board. Use an ammeter to measure the current going into the radio. My bench supply has an amp meter built in, so that's what I use. I hook up a dummy load, because it seems like the right thing to do.
Turn the radio on, and put it in sideband mode. Turn the mic level all the way down. Key the mic for a few seconds and note the current reading. Should be less than an amp, at least it was on mine. I think it was 0.7 something.
Key the mic while slowly turning up vr1. Watch the meter to see if the current jumps. Mine would go from 0.7 straight to 2.3. When the current jumps up, the transistor is turned on and conducting. We want to have it set right before it turns on. Unkey the mic and turn it back down. Key up and start turning it up again. Note the current slowly increasing and remember what it was, right before it jumps. Keep the mic keyed and turn it back down to the point where it was before it jumped. Then turn it down just another hair because it doesn't seem right to have the bias sitting right on the edge of turning on.
You will most likely have to adjust the AM carrier level to bring it down after this. Hook it up and start talking. Pay attention to the heat sink temperature. It's normal for these things to put out some heat, but if you touch it and say "Wow", then put it back on the bench and check your work.
Ok, in a nutshell. Basically it's what you would do to set the bias on a radio that has no mirror board. Use an ammeter to measure the current going into the radio. My bench supply has an amp meter built in, so that's what I use. I hook up a dummy load, because it seems like the right thing to do.
Turn the radio on, and put it in sideband mode. Turn the mic level all the way down. Key the mic for a few seconds and note the current reading. Should be less than an amp, at least it was on mine. I think it was 0.7 something.
Key the mic while slowly turning up vr1. Watch the meter to see if the current jumps. Mine would go from 0.7 straight to 2.3. When the current jumps up, the transistor is turned on and conducting. We want to have it set right before it turns on. Unkey the mic and turn it back down. Key up and start turning it up again. Note the current slowly increasing and remember what it was, right before it jumps. Keep the mic keyed and turn it back down to the point where it was before it jumped. Then turn it down just another hair because it doesn't seem right to have the bias sitting right on the edge of turning on.
You will most likely have to adjust the AM carrier level to bring it down after this. Hook it up and start talking. Pay attention to the heat sink temperature. It's normal for these things to put out some heat, but if you touch it and say "Wow", then put it back on the bench and check your work.
Need some help with one of these RFX95HD amps on a superstar 3900 single final BJT.
Brand new RFX95HD,
Radio has no swing mods, limiters intact,
Replaced Final and driver cause of low output with just radio,
Got radio itself running great, 3w key swing to 25w peak,
Hook RFX up and automatically swings to about 75w peak,
Within 6 seconds swings drops to 50w peak, unkey for about 10 seconds, key up swings to 75w peak, 6 seconds later drops to 50w.
Unhook amp, radio itself doesn't drop power at all.
Driver bias set to 50ma, final set to 100ma, nothing gets hot in radio at all, amp gets quite warm but not hot enough to scream ouch.
I've checked and rechecked everything, nothing is wrong with radio or installation.
I did not touch the bias VR on the amp, it's setting at the halfway mark.
On SSB it dims the meter light a lot, amp meter on my power supply (set at 13.8v) jumps from 3a idle up to about 8a maybe 9a on deadkey of 5w and swings up to about 13a when modulating.
To me, sounds like the mosfet in the amp is shutting down for some reason.
Any advice is highly appreciated...
Brand new RFX95HD,
Radio has no swing mods, limiters intact,
Replaced Final and driver cause of low output with just radio,
Got radio itself running great, 3w key swing to 25w peak,
Hook RFX up and automatically swings to about 75w peak,
Within 6 seconds swings drops to 50w peak, unkey for about 10 seconds, key up swings to 75w peak, 6 seconds later drops to 50w.
Unhook amp, radio itself doesn't drop power at all.
Driver bias set to 50ma, final set to 100ma, nothing gets hot in radio at all, amp gets quite warm but not hot enough to scream ouch.
I've checked and rechecked everything, nothing is wrong with radio or installation.
I did not touch the bias VR on the amp, it's setting at the halfway mark.
On SSB it dims the meter light a lot, amp meter on my power supply (set at 13.8v) jumps from 3a idle up to about 8a maybe 9a on deadkey of 5w and swings up to about 13a when modulating.
To me, sounds like the mosfet in the amp is shutting down for some reason.
Any advice is highly appreciated...
Well, well, well...
After letting it sit a bit, turned on, I heard a loud "POP". Jumped up and looked for the pop sound, it was the 470uf 16v electrolytic cap on the edge of the amp board, next to a diode and the red (+13.8v). The amp still put out power, but only 45w. Yanked the board out the amp, yanked that blown cap out, checked the diode next to it (tests fine). I then noticed signs of severe heating on the bottom of the 9530, so I yanked it out.
Gonna replace the 470uf 16v cap.
Gonna replace the ERF9530 with a IRFP260N and see if it will work in place of the overheated 9530.
I called the owner to notify him. He was honest in telling me that he did hook the 13.8v wires and the input/output wires up, but not the 8v transmit line. He told me he at first had the red and black 13.8v wires crossed at first and it blew the fuse for the amp. I told him he should've left it alone for me to do. I think he may have messed the amp up when he hooked the red and black wires backwards, which blew the fuse.
Before I go through all this, will the IRFP260N work in place of the 9530?
After letting it sit a bit, turned on, I heard a loud "POP". Jumped up and looked for the pop sound, it was the 470uf 16v electrolytic cap on the edge of the amp board, next to a diode and the red (+13.8v). The amp still put out power, but only 45w. Yanked the board out the amp, yanked that blown cap out, checked the diode next to it (tests fine). I then noticed signs of severe heating on the bottom of the 9530, so I yanked it out.
Gonna replace the 470uf 16v cap.
Gonna replace the ERF9530 with a IRFP260N and see if it will work in place of the overheated 9530.
I called the owner to notify him. He was honest in telling me that he did hook the 13.8v wires and the input/output wires up, but not the 8v transmit line. He told me he at first had the red and black 13.8v wires crossed at first and it blew the fuse for the amp. I told him he should've left it alone for me to do. I think he may have messed the amp up when he hooked the red and black wires backwards, which blew the fuse.
Before I go through all this, will the IRFP260N work in place of the 9530?
Shadetree Mechanic
Delaware Base Station 808
Chris, how did the rfx perform on ssb in the 86v installation? I know AM they are impressive but have not experienced the ssb side.
Shadetree Mechanic
Delaware Base Station 808
The RFX works great on SSB. On the 86v, I adjusted the bias because I could hear that it wasn't as clear on SSB as am was. After adjusting the bias, it sounds great, and I am still using it in my truck.
Your brave and dedicated dude, you've donated a might fine specimen for the experiment and I hope it turns out really well!
Is this the 86V with the RFX95HD mounted to the back of it? What are you getting out of it for power with it? Thanks.