B.E. 1.5

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Larry Milliken
Posts: 64
Joined: Fri Feb 14, 2014 7:39 am

B.E. 1.5

Post by Larry Milliken » Mon Feb 26, 2018 7:10 pm

A BE 1.5 using a 3Cx1500A7 is having intermittent plate overloads. A reset brings it right back on line and will run fine for days and then another overload. I can find nothing wrong unless it is the incoming AC occasionally going too high for a moment. The tube is very old but still makes good power and the grid current is correct. Any thoughts? Thanks.

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kkiddkkidd
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Location: Lawrenceburg, TN

Re: B.E. 1.5

Post by kkiddkkidd » Wed Feb 28, 2018 9:50 am

Larry Milliken wrote:
Mon Feb 26, 2018 7:10 pm
A BE 1.5 using a 3Cx1500A7 is having intermittent plate overloads. A reset brings it right back on line and will run fine for days and then another overload. I can find nothing wrong unless it is the incoming AC occasionally going too high for a moment. The tube is very old but still makes good power and the grid current is correct. Any thoughts? Thanks.
I have absolutely zero experience with that transmitter but If the tube is really old, I would suspect it first as well as whatever they used for a plate blocker. Old tubes (heck even brand new ones) can arc internally occasionally without junking themselves completely. It could also be the exciter unlocking or swerving around, or any number of other faults. A bad power control circuit could do it...

If you have internet at the site, an IP camera recording the TX would be a good tool especially if it can record sound.

Good luck,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

TPT
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Joined: Mon Dec 03, 2007 3:18 pm
Location: St. Marys, WV

Re: B.E. 1.5

Post by TPT » Wed Feb 28, 2018 10:28 am

IPA? That might also be the problem if the final is momentarily losing drive.

Larry Milliken
Posts: 64
Joined: Fri Feb 14, 2014 7:39 am

Re: B.E. 1.5

Post by Larry Milliken » Tue Apr 24, 2018 10:10 am

Just to let you folks know, I changed out the tube with a NOS-could not find a new Eimac-and the plate overload problem went away. I'll keep the old tube for an emergency since it makes full power even though the occasional overload.

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