I have been rebuilding an eagle 500 That is in fairly nice condition, all original with original tubes. I have replaced 80% of the capacitors the only ones left are the silver mica caps in the final drive section. I have replaced the transistors for the preamp and ssb circuit but i still am getting a real bad squeal when used on the ssb side, I'm assuming it is feedback somewhere but I'm running out of ideas on where this squeal is coming from The amp works great on the am side it will put out 500 watts easy. I still have to replace the diodes on the transformer board but i don't believe that is the cause of the ssb squeal. Any ideas on what part of the circuit is most likely to be causing this feedback Radio transmits great on ssb until you run it through the amp.I still have not changed the resistors in the ssb circuit yet but most of them have tested fairly good.
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Eagle 500 squeals on the ssb side
- Thread starter histeel
- Start date
Check all the grounds, especially tube sockets. Can you turn the mike gain down and make it go away? Does it do it in both low and high power. Also make sure the ALC is not turned wide open in the radio. Squeals can be boogers at times to find. Figure when all is said and done it'll be a ground issue though.
I have tried all of the above except the ground re soldering, There are a few places along the grid there are ground lugs. I have inspected the foil side of all the boards for cold joints and havent found any thing yet I get the feedback in upper and lower side with mike gain and power turned as low as it will go. It does have 2 rectifier diodes in the ssb circuit That have not been changed yet, waiting on them to arrive. would like to get the diodes changed on the power supply board it seems like it is down on voltage during modulation, a lot of backswing. Thanks Roger
Change the diodes and make a post as to what happened if anything. I wouldn't think it the amp is working good on AM that it would cause a problem on SSB but I ain't working with good tools for the most part. I am assuming (bad sometimes) that you have replaced the power supply caps also?
One other thing..........does another radio also squeal with this amp and does it squeal into a dummy load? Sometimes you have to eliminate everything there is and if you still have a problem......keep looking, not trying to be cute but sometimes that is the worst problem to get rid of.
One other thing..........does another radio also squeal with this amp and does it squeal into a dummy load? Sometimes you have to eliminate everything there is and if you still have a problem......keep looking, not trying to be cute but sometimes that is the worst problem to get rid of.
Well I have changed all the diodes,capacitors, transistors, and re soldered all grounds, and have had no change. I am starting to believe that the galaxy rig i am driving it with is a little more than it can handle on the ssb side, or there is a problem with 1 of the tubes, although i am getting around 600 watts out on the AM side the Galaxy dx 2527 may be a little more than it can handle. I am keeping the AM drive down below 7 watts but i believe the pep watts on the ssb side may be to much.
Had a great deal of success today, I was using the amp with the covers removed, replacing the covers did help some what but i was still getting a little distortion and a slight squeal. I have been running on as low a wattage as i can make my galaxy run with the mic gain all the way down, thinking it was over driving the amp. Today I tried something new and put more wattage and more mic gain into it and the squeal and distortion went away. Made several contacts into Ireland and Scotland running about 1100 watts pep, and had good signal reports also. I think i could have been under driving the amp.