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Re: [Amps] LK500-ZB

To: TexasRF@aol.com,royanjoy@ncn.net,amps@contesting.com
Subject: Re: [Amps] LK500-ZB
From: Alek Petkovic <vk6apk@bigpond.com>
Date: Thu, 10 Sep 2009 06:14:54 +0800
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Yep, I've done it and it cleared the fault ok. Only problem is that I 
am now too chicken to test the tube in the amp.

73, Alek.
VK6APK


At 02:54 AM 10/09/2009, TexasRF@aol.com wrote:
>Has anyone tried to blow a grid to cathode short with a high current pulse
>of energy? Such as touching the shorted pins for an instant with a car
>battery.  At this point seems not much to loose by trying.
>
>73,
>Gerald K5GW
>
>
>
>
>In a message dated 9/9/2009 1:46:57 P.M. Central Daylight Time,
>royanjoy@ncn.net writes:
>
>About:
>
>
>"...No visible damage to the case, but now when the  amp is turned on, but
>in
>standby, the plate current reads about 200mA and  the grid current is
>pegged
>negative. Plate voltage is lower than what it  used to be, about 2600 V.
>Switching between RX/TX doesn't seem to have any  affect, I can hear the
>relay kick. One final observation, in RX, one tube  starts to glow orange,
>while the other stays the normal light yellow  color...(etc.)"
>
>
>My ZB had that happen several times when using  Eimac tubes AND before I
>installed a good in-rush protection circuit plus  ridded it of parasitics.
>Never has occured since (with RFP tubes). It's  surely a grid - to - fil
>internal short.
>
>73,   Roy    K6XK
>
>
>
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