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Author Topic: Results of turning on SB-220 after 28years  (Read 615 times)
K1PEK
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Posts: 51




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« on: February 02, 2009, 09:21:11 AM »

in Early Jan. I put out a request ref. proper procedure for firing this up after many years. Indicated I would report on the outcome. Other than
fixing a flaky phono plug jack for the ant relay, it runs fine.  Just plugged it in and turned it on. No smoke or critters escaping (did check it out first... no dust/rust/bubble up or boilovers).
  Tnx agn for the input,  73,  Steve  K1PEK  
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WB2WIK
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« Reply #1 on: February 02, 2009, 11:04:35 AM »

Good news, and pretty amazing!

3-500Zs were never noted for long shelf life, I'm surprised they're not gassy after 28 years.

Use it in good health!
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WW5AA
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« Reply #2 on: February 02, 2009, 01:47:58 PM »

Great, In my experience usually the caps dry out. Have fun. Thanks for checking back! Very few do.

73 de Lindy

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K4JJL
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Posts: 501




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« Reply #3 on: February 02, 2009, 02:30:09 PM »

Might want to use a variac to bring it up slowly next time you fire up equipment that's been on the shelf a while.  Old caps that are sitting around tend to "BANG" when powered on full voltage.
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KC8VWM
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« Reply #4 on: February 02, 2009, 10:41:38 PM »

I would recommend replacing the caps even if it is working right at the moment.

Problem with using the ones you have now is that they might have dried out and if they didn't fail yet, they might in the immediate future.

Resistors might also drift past 10 %  and as Steve mentioned earlier the tubes might be gassy and require gettering.

So just because you plug it in and it works, doesn't mean it doesn't require any maintenance to keep it that way.

Just speaking from my own experience with vintage electronics. Although using a variac is a good idea when powering older electronics, Variacs are not capable of repairing dried out caps that may be in need of replacement.

I guess you can say I am not a big fan of "reforming" caps using a variac. This is because I find that purchasing a fresh set of caps and installing new resistors are often much cheaper to replace than HV transformers, shorted variable capacitors, blown meters and shot output tubes.

Just my own experience, that's all.

73 de Charles - KC8VWM
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W8JI
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« Reply #5 on: February 03, 2009, 05:22:53 AM »

Steve,

Your experience mirrors the experiences I always have when turning on old gear. If the caps are good they take it fine, if they are not then you really needed to change them all out anyway.

One thing the SB220 does is run the HV at 70 % voltage in the CW position, so as long as you start in the CW position you are good to go. If the caps aren't bad and the tubes don't arc when you step up to SSB, there is no reason to change anything.

Leave it as you find it unless you have something go bad.

73 Tom



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K1PEK
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« Reply #6 on: February 03, 2009, 06:01:14 AM »

Tnx gentlemen for the latest responses, all worth noting.  Tom, W8JI, I hope that you received my email back in early Jan.  If not, please give me an email address so I can copy you.   You must get a lot of emails and I am amazed that you even have time to respond to this followup.  You have certainly provided a multitude of info to hams, via many venues, as well as a signficant contribution to design. My email is sdavis@DavisRF.com
   73 to all, Steve   K1PEK        
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W5DWH
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« Reply #7 on: February 03, 2009, 01:42:45 PM »

I replace all electrolytic caps in old equipment. When I take a "new" one out of my parts bin, I always put it on my Sencore Z meter first. If it needs reforming the Sencore will do it without it blowing up in your face (like powering up a piece of equipment at full power might do). Some NOS caps may be 10 years old or older themselves and need reforming or at least checking for excessive leakage and ESR. Nothing like putting a supposedly good cap in a piece of equipment and it being bad.

73 W5DWH Donald
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