The tube may be fine, but unles you KNOW that, its likely not. I guess lots of these were used in broadcast service, and when they started arcing over, they were pulled and thrown in a box for sale at the hamfest.
I know I bought a lot of them at fests for very little, and 99% wont work more than a few transmissions before arcing. The new ones have been in for years without problems... I was getting 3cx800's as pullouts and 80% of them were useless also. Brett N2DTS ----- Original Message ----- From: "Rev. Robert P. Chrysafis" <[EMAIL PROTECTED]> To: "Brett Gazdzinski" <[EMAIL PROTECTED]>; "Discussion of AM Radio in the Amateur Service" <[email protected]> Sent: Thursday, November 29, 2007 9:42 AM Subject: Re: [AMRadio] fs/ft: Eimac 4CX250B - Unknown Condition > Ok, > > I don't know much about this high power stuff. highest power tube tranny i > have is 36 Watts on the AM BCB for carrier current use. > > and actually that is the only tube tx i have. it's going to be a learning > experience to get it going again. > > ----- Original Message ----- > From: "Brett Gazdzinski" <[EMAIL PROTECTED]> > To: "Discussion of AM Radio in the Amateur Service" > <[email protected]> > Sent: Thursday, November 29, 2007 9:37 AM > Subject: Re: [AMRadio] fs/ft: Eimac 4CX250B - Unknown Condition > > > >I avoid 4cx250 pull outs as they are almost always bad. > > They may test fine, but they arc over after a while in use. > > I have about 30 of them that do that. > > > > As they are used, the stuff they made to coat the cathode > > (so it emits electrons) gets deposited all over inside the tube, > > and at some point they start arcing over. > > It just seems to come down to run time (filiments on). > > > > They tend to work for a while, then arc, and the more > > you use them the more they arc, till next time when you > > start over again, each time getting shorter before they arc. > > > > Maybe reducing the voltage to say 1000 volts > > (down from 2000) might give them more time. > > > > I consider these tubes worthless unless they were not used > > or have low hours on them. > > > > Not sure what new ones go for, I got 4 new ones a few years ago > > for $160.00, used ones used to be $5.00 and not usualy worth that. > > > > Brett > > N2DTS > > > > > > > > > > ----- Original Message ----- > > From: "Rev. Robert P. Chrysafis" <[EMAIL PROTECTED]> > > To: <[email protected]> > > Sent: Thursday, November 29, 2007 9:25 AM > > Subject: [AMRadio] fs/ft: Eimac 4CX250B - Unknown Condition > > > > > >> I got this from a radio station in a lot of stuff and it has been > >> floating > >> around my house for quite some time. I have no use for it as i'm into > >> QRP. > > I > >> have no idea if it works or not. It looks like it's in good condition. > >> > >> I'll swap it for an interesting technical trinket or best cash offer plus > >> shipping. > >> > >> My interests are Part 15 AM Microcasting and Computers. > >> > >> > >> Thank You, > >> > >> Rev. Robert P. Chrysafis > >> Universal Life Ministries > >> http://www.ulc.org > >> > >> Moderator Hunterdonfree > >> http://groups.yahoo.com/group/hunterdonfree > >> Moderator NeighborhoodInformer NJ/PA > >> http://groups.yahoo.com/group/NeighborhoodInformerNewJersey > >> http://groups.yahoo.com/group/NeighborhoodInformerpennsylvania > >> > >> ______________________________________________________________ > >> Our Main Website: http://www.amfone.net > >> AMRadio mailing list > >> List Rules (must read!): http://w5ami.net/amradiofaq.html > >> List Home: http://mailman.qth.net/mailman/listinfo/amradio > >> Help: http://mailman.qth.net/mmfaq.html > >> Post: mailto:[email protected] > >> To unsubscribe, send an email to [EMAIL PROTECTED] with > >> the word unsubscribe in the message body. > > > > ______________________________________________________________ > > Our Main Website: http://www.amfone.net > > AMRadio mailing list > > List Rules (must read!): http://w5ami.net/amradiofaq.html > > List Home: http://mailman.qth.net/mailman/listinfo/amradio > > Help: http://mailman.qth.net/mmfaq.html > > Post: mailto:[email protected] > > To unsubscribe, send an email to [EMAIL PROTECTED] with > > the word unsubscribe in the message body. > > > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:[email protected] > To unsubscribe, send an email to [EMAIL PROTECTED] with > the word unsubscribe in the message body. ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected] To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
