New 3-500ZG Tubes / Do you need to break in? - Amplifiers Forum at eHam.net

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eHam.net Forum : Amplifiers : New 3-500ZG Tubes / Do you need to break in?

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New 3-500ZG Tubes / Do you need to break in?	Reply
by KB4MUV on October 14, 2009	Mail this to a friend!
I have a Heathkit SB-220 that was in storage for several years. When I turned it on, it appears one or both tubes were gassy and that took out several other componets. Well we have rebuilt her and she appears to be good to go. Now I have ordered 2 brand new 3-500ZG tubes from RF Parts to install. Now my question is, what do I need to do to break in these tubes if anything????? I understand I should whipe down the globes with alcohol swabs to get figerprints off to prevent hot spots. But I have also heard I should run them without the anodes attached for 24 hours and other assorted stuff to break them in. I have retubed radios before, but never an amplifier with these type of tubes. This beast has taught be so much!!!! Ha! Ha! What might the words of wisdom be on this endeavor????? Thanks in advance for any information. Ken KB4MUV

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by W1QJ on October 14, 2009	Mail this to a friend!
New tubes are usually gettered from the factory and do not require any special treatment. I have bought numerous tubes from RF Parts and I just installed them and away I went. Never had a problem. Usually the .82 grid resistors blow out when a gassy tube flashes over. I have the OEM replacement resistors for that if you need any. 73 Lou

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by K6AER on October 14, 2009	Mail this to a friend!
Plug the tubes in and turn the amplifier on. The Thoriated Tungsten filaments are ready to go as soon as they glow. Older glass tubes can become gassy, that is oxygen migration into the tubes via the metal base pins and some times you will have a high voltage flash over. The good news if you do have flash over it will generally dissipate any oxygen that has leaked into the tube. Bad news it may take out a anode or cathode resistor. The only way you can getter the tube is to have the anode heated up from use. The filaments lighted is not enough heat to getter the tube. Do some reading on Tom’s web site at W8JI. He has a boat load if information out there.

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by K4TLJ on October 14, 2009	Mail this to a friend!
Just a wild idea from a new guy... Has anyone ever tried using a large magnifying glass to focus sunlight onto the anode to heat the anode and getter the tube without applying HV?

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by K6AER on October 14, 2009	Mail this to a friend!
I think the amplifier heating the tubes in actual operation might be much easier. News Item just in from MSNBC: “A Ham today collapsed from heat stroke today while trying to heat a tube with out electricity. The older ham was scene holding a gigantic 42” magnifying glass over the little tube from an unknown piece of equipment. Just as the John Q. Ham collapsed, the magnifying glass rolled down the driveway and came to rest against a tree. The tree caught fire setting 60 acres ablaze. The Pounduk Fire department was able to put out the blasé in just under 2 hours. John Q. Ham said he had insurance from the ARRL but the ARRL spokes person was not available for comment if this was covered under the ham umbrella policy. It is unknown if this new method of making tubes glow is considered a green technology but Al Gore (Ex Vice President to Clinton) will be giving a series of lectures at Dayton ham convention next year on how this magnifying glass technology will produce thousand of jobs in the linear amplifier industry. At this point, night time technology is still years away from general ham tube heating use. An unnamed spokesperson for PETA felt this technology is not with out risk for it is rumored several moles were displaced from the filed fire”

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by KB4MUV on October 14, 2009	Mail this to a friend!
Thanks Lou for your reply and offer... I have some spares. I did go ahead and replace the whole board. And had ordered some of the res. Ken KB4MUV

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by KB4MUV on October 14, 2009	Mail this to a friend!
Thanks K6AER for the info on the website... I will go there and see what they have.... Yeah the ole tubes were gassy and beyond saving. And figured that looking on eBay wasn't the route to go to replace them. Ken KB4MUV

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by WB2WIK on October 14, 2009	Mail this to a friend!
3-500ZGs don't require any special burn-in time. Using them until the anodes glow red/orange is what keeps them gas-free. This is one tube design that lasts longer when frequently used than it does "on the shelf." Not all tubes are like that, but this one is. Although I do keep "spares" around, I rotate the spares through an active amplifier at least once a year so the spares on the shelf were always recently used. Buying new spares and letting them just sit on the shelf isn't a good idea. WB2WIK/6

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by K4DPK on October 14, 2009	Mail this to a friend!
Mike you are a trip! Phil C. Sr. k4dpk

RE: New 3-500ZG Tubes / Do you need to break in?	Reply
by K4TLJ on October 14, 2009	Mail this to a friend!
Well at least my suggestion brought out the latent satirist on the forum. :)

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