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@cox.net>
To: <amps@contesting.com>
Cc: <ham_amplifiers@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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