FM xmiiter problem before I call the real engineer

fmksey · Post by **fmksey** » Wed Jul 01, 2009 11:47 pm

And not too many of them left - and he's about 200 miles away. So here is the problem---- I have a Wilkinson 2500E, 83 vintage. It was rebuilt 1 year ago (everything new, really, except the box) - we pulled the IPA and exciter - and from other folks I've talked with they say the exciter was shit, but the everything else, ok. The rep from Wilkinson must have spent alot of time in north central/west Texas because about 10 stations have Wilkinson xmiitters. I need 60 watts of drive and I'm doing it with a DB 500. Now the problem --- the exciter output will not stay stable --- and it started about a months ago. It wil go from 10 watts to 80 watts almost everyday now. And at 60 watts --- plate current, screen volts/current -- everything right where it should be.

Any ideas?

Mark

oldtvman2 · Post by **oldtvman2** » Thu Jul 02, 2009 12:06 am

what are these readings when the output drops? what is the vswr into the amplifier? when normal and when the power drops?? could be cableing to the amplifier or the input circuit of the amplifier? what about heat in the transmitter building.

engineer · Post by **engineer** » Mon Jul 06, 2009 6:25 pm

As oldtvman stated, If the power is reducing I would look at vswr into the IPA or heat. If the power is going up, I would guess some type of problem exists in the control circuit. You really need to look at the schematic to see how the power output is controlled. I've never worked with a DB500. Does it have a multi-test meter? Check there first. Good luck.

lastone · Post by **lastone** » Mon Jul 06, 2009 7:57 pm

You may simply have a bad output control. Turn the power out control SLOWLY down and up. Watch for any Jumps. See if it 'wiggles' (gently) and jumps at various locations of its range. If the control is carbon, I'd almost bet it's loosing contact.

Just a thought.

oldtvman2 · Post by **oldtvman2** » Fri Aug 07, 2009 1:54 pm

What did you find?

Cameron · Post by **Cameron** » Fri Aug 07, 2009 3:52 pm

...too electrocuted and dead to respond.
Did we mention pulling the disconnect and using the wand-of-our-savior before troubleshooting inside the cabinet?

oops

genlock · Post by **genlock** » Fri Aug 07, 2009 3:59 pm

Cameron wrote:...to electrocuted and dead to respond.
Did we mention pulling the disconnect and using the wand-of-our-savior before troubleshooting inside the cabinet?

oops

Important and sometimes forgotten professional safety tip.

Cameron · Post by **Cameron** » Fri Aug 07, 2009 4:02 pm

eh...I'm still kickin'.
See you at hamfest tomorrow.

genlock · Post by **genlock** » Fri Aug 07, 2009 4:03 pm

I will be there.

Cameron · Post by **Cameron** » Fri Aug 07, 2009 4:06 pm

Good. You can boo me after my Extra Class.

genlock · Post by **genlock** » Fri Aug 07, 2009 4:10 pm

Raquel going to get her license someday?

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FM xmiiter problem before I call the real engineer

FM xmiiter problem before I call the real engineer

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