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Author Topic: Ten Tec Titan 425 - Drive Levels & Arcing  (Read 562 times)
N3HEE
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« on: November 30, 2017, 09:40:14 AM »

It takes about 70 watts drive to get 1500 watts output CW from my Titan 425 on 160 meters.  Grid current is reading about 50ma on the meter.  It takes about 50 watts on 80 an 40 meters with about 45ma grid currents.  I'm also starting to experience some random arcing on the band switch once in a while.  No signs of arcing anywhere else.  I gave the RF deck a good cleaning.  I heard that arcing could be caused by a tube going bad.  Are my tubes getting soft ?
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Joe
N3HEE
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W1QJ
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« Reply #1 on: November 30, 2017, 10:00:39 AM »

I have seen more than one Titan 425 with bad band switch problems on 160 meters.  For whatever reason I am not really sure.  It could be because of hams using compromise antennas on that band.  One a band switch arcs the tendency for it to arc again increases if it begins to "track".  There could be any number of reasons why any band switch arcs in any amp.  If you experience arcing you should immediately determine what the cause is and address the problem.  It is difficult to say what any particular reason is in anyone's arcing from afar.   
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N3HEE
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« Reply #2 on: November 30, 2017, 11:30:04 AM »

It also arcs on 80 meters. The arcing rarely occurs though.  Only when I first tune up going to higher power.  Never while operating.  I have also started to notice that the input SWR will jump up on 80 and 40 meters.  I can wiggle the band switch and it will go back down.  So something is up with the band switch.    The band switch looks to be in good condition.  Contacts look very good.  I noticed some blackish looking residue on the rear most wafer near the 160 meter position.  I gave everything a good cleaning and removed some dust that was in that area.  Like you say its hard to figure out whats wrong.  I gave everything a good cleaning and removed some dust that was in that area.  We shall see.  If it gets worse I will send it your way.  Thanks for your help Lou.  -Joe
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Joe
N3HEE
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N4ATS
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« Reply #3 on: November 30, 2017, 12:32:58 PM »

Arcing is the internal bushings starting to go bad and may be on the band selector switch. Thats a common issue with the Titan line.
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N1UK
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« Reply #4 on: November 30, 2017, 02:06:41 PM »

Quote
It takes about 70 watts drive to get 1500 watts output CW from my Titan 425 on 160 meters.  Grid current is reading about 50ma on the meter.  It takes about 50 watts on 80 an 40 meters with about 45ma grid currents

I will take some measurements but that is a lot of drive. My drive levels are around 30 to 40 watts. Those tubes look to be pretty soft but I will post some readings here


73 Mark N1UK
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N3HEE
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« Reply #5 on: December 04, 2017, 08:03:17 AM »

Thanks Mark.  That would be helpful.  I used the amp this past weekend in ARRL 160 test with no issues.  It took 65 watts drive to get near legal limit output.  About 60 ma grid current.  I cant see putting much money in this amp if the tubes are getting soft. 
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Joe
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« Reply #6 on: December 04, 2017, 08:18:52 AM »

Thanks Mark.  That would be helpful.  I used the amp this past weekend in ARRL 160 test with no issues.  It took 65 watts drive to get near legal limit output.  About 60 ma grid current.  I cant see putting much money in this amp if the tubes are getting soft. 

Does that mean you sell the amp when it needs to be retubed?
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N3HEE
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« Reply #7 on: December 04, 2017, 10:05:49 AM »

In this case yes.  I am planning on buying a modern solid state amp before I retire and don't want to put any more money into this amp.
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Joe
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« Reply #8 on: December 04, 2017, 12:23:49 PM »

In this case yes.  I am planning on buying a modern solid state amp before I retire and don't want to put any more money into this amp.

No problem, I can understand that. When you decide you want to sell (less tubes) let me know.  Retirement is nice if you can afford it.
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