[Amps] lk-450NTC

[Carl]

Those NTC amps have a bad habit of arcing the undersized fixed tuned 
variables. Most I get in here for service are changed to regular Tune amps 
or converted to 6M where either way they work just fine.

Carl
KM1H


---- Original Message ----- 
From: "ko1h" <ko1h at cox.net>
To: <amps at contesting.com>
Cc: <ham_amplifiers at yahoogroups.com>
Sent: Thursday, March 15, 2012 11:28 PM
Subject: [Amps] lk-450NTC


> Hi all,  Just acquired a lk-450ntc.  Had some trouble getting the tube to 
> light but then all was well for a few days.  ( I did a stupid when trying 
> to get the tube to light and will have a nice scare on my left pinky to 
> tell tales about)  But be that as it may.  After getting the tube to light 
> (Friday last)  I hooked it up and was getting power out on 75 into a dummy 
> load and antenna.  Didn't mess with it for a few days turned it on tonight 
> and a few seconds after hitting the power switch I got a pop in and I 
> think I saw an arc in the rf compartment.
>
> Figuring heck this happens ( I used to own a few sb220/1's that loved to 
> bang everyonce in a while) I kept the amp in standby verified that the 
> exciter was turned down enough and the swr to the antenna was good and 
> fired it up.  Well SWR back to the radio when the amp is keyed to goes 
> through the  roof and the idle plate current in the amp drops to zero. 
> Placing the amp in standby and through to the antenna a just fine.  Tube 
> is lit.  2900v on the meter for idle dc voltage.  Relay can be heard 
> engaging.
>
> Due to this thing biting me last week ( my own stupid) had it turned on 
> and touched it with the covers off I know luck I'm here)  I've got it 
> unplugged and sitting for the night before I take the covers off.
>
> Any place I should start to look?
>
> Perhaps reseating the tube.  The socket on this thing does not please me 
> and will likely get replaced eventually.
> Relay?
> Glitch resistor on the tub?
>
> Anything else?  (aka the reason I'm posting this most people know 
> more/better than I do. )
>
>
> Thanks de John ko1h
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