AF9J
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« on: February 28, 2008, 09:47:07 AM » |
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Hi Peeps,
Well, as I mentioned in another thread, my Viking 2's PTT is working fine. I also mentioned that modulation was good, except for the modulation current running away (which turned out to be a bad 807, that was arcing over).
Last night, I got around to finally start replacing the remaining paper caps. I started with C10 & C11, which are filter caps. They're supposed to 15 microfarads, and 450V rated. Well, I had a dual 15 microfarad that was rated at only 350V. That's trouble in the making right there. Also one wire wasn't hooked hooked up on the dual cap (more on that later). I wanted to keep the mounting ring for the old C10/C11 dual cap, for mounting the replacement caps in (2, 22 microfarad units rated at 450V each). I couldnt unscrew the ring, and hope to remount it, without unbolting one of the big power transformers from the other side of the chassis (no thanks), so I could rescrew in the screw for the mounting ring. So, I cut the leads on C10/C11 and tried to wiggle it loose. Not a chance! I took out the wire cutter, and started cutting through the dual cap. Doing this I was able to remove the dual cap from the mounting ring. The cutter should have had some wet, sticky material on it (electrolyte) from cutting through it. There was none. Examining the dual capacitor remains showed them to be as dry as a bone. So, it was pretty much shot.
I was able to confirm where the positive leads from C10 & C11 were supposed to go (on either feed side of choke L2). This is when I learned what the unattached wire on the old dual capacitor must have been - the negative lead for both C10 & C11. It had NOT been wired up at all. Go figure! Add another one to Hammy Hambone's anthology of greatest hits. It was late, so I'll wire in the new C10 & C11 tonight. I have three concerns:
1. Compared to the wires off of the old dual C10/C11, the leads on my new capacitors (both are radials), look pretty wimpy. I wonder if they'll have problems handling the current. 2. The mounting ring is too small for both capacitors. As of this time, my thought is to tie wrap the new C10 & C11 to the mounting ring (I really don't want them laying on the chassis). 3. I need to find a decent ground point, that isn't umpteen inches from C10 & C11 (you know, the old "shorter leads help to keep noise down" bit).
BTW, I have to replace a .02 microfarad paper cap in the audio section. For some reason its rating is listed as 400 W.V. What's W.V.?
73, Ellen - AF9J
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