[Amps] 8122 op temp in NCL-2000 amp

[Carl]

The PS bleeder resistors are right behind the tubes as well as the 
ventillation holes for the capacitor bank underneath.

You can also operate SSB in the CW position.

Carl
KM1H
National Radio 1963-69
Member of NCL-2000 Design Team



----- Original Message ----- 
From: "Frank T Brady" <franktbrady at comcast.net>
To: <amps at contesting.com>
Sent: Saturday, March 14, 2009 10:12 AM
Subject: [Amps] 8122 op temp in NCL-2000 amp


>I operate SSB with my NCL-2000 only to chase 'new ones'.
> While doing this on 17m I noticed that the top lid above the tubes was
> awfully hot.
> The high temperature persisted in SSB mode even if I wasn't 
> transmitting.
> SSB uses approx 2800v and idle current is 200 ma.
> I put a digital thermometer on the lid above the tubes and recorded 
> some
> temps.
>
> 80    Ambient (amp cold)
> 87   Amp filaments only
> 97   CW HV on
> 126   SSB HV on
>
> The temperature was still rising slowly in the SSB case when I decided
> to stop the test.
> I haven't measured the SSB temp when transmitting periodically because
> I'm afraid something might be amiss.
> The fan seems to be moving a decent amount of air upward around the 
> tubes.
> Is there a way to determine if the SSB temp is normal?
>
> Thanks and 73
> frank w0ecs
>
>
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