[Amps] SPIKE Question????

[R.Measures]

Ted -- I worked on a Titan that was doing this.  The problem turned out 
to be loose gold particles in the 3cx800s.  The tubes were made useable 
again by moving the loose gold into the tube bases by tapping the anode 
caps and watching the anode-grid leakage current decrease on the 
high-pot tester.  When the leakage stops decreasing, I stop tapping.  
//  If you don't have access to a high-pot, I will test your tubes for 
the price of return postage.
--  note --  The reason that the problem typically shows up with RF is 
that since +V attracts gold particles, the more the anode-V swings 
positive with a signal, the stronger the attraction of the gold to the 
anode.  When too many gold particles get sucked up onto the anode-grid 
insulator, the amplifier will shut down. 
  good luck

On Nov 24, 2004, at 7:27 PM, TED & JOYCE wrote:

> Hi All,
>    Just found this reflector and hoping someone out there may have an 
> answer short of new tubes to my problem.....Am running an Kenwood 870 
> into an Alpha 87a (about 5 years old)......On phone there is now 
> problem with putting out full power...once I go to CW if I drive it 
> and output is over about 5-600 watts it just completly shuts 
> down.....NO deffaults lites  or anything.....Talked with alpha one 
> time about this and they told me tubes were getting soft which I am 
> sure they are.......Short of putting 6Bills in to some new tubes is 
> there any suggestions to get around this intial volatage strike to the 
> amp from the exciter... and if it is necessary to retube is there any 
> way to avoid these  kind of problems in the future......Yes before 
> anyone replies it is not in feed lines antennas etc etc.........Same 
> freq. same everything fine on SSB intial spike on CW turns it 
> off............Thanks and hoping to hear from somebody that has been 
> down this road before................Best of 73"s and a very Happy 
> Thanksgiving too all...........
> Ted     K9HUH      "huh:
>
>
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org