Re: [Amps] Ten Tec 425 amp

[rlm < <r@somis.org>>]

On Monday, November 3, 2003, at 04:40  AM, john naberezny wrote:

> Hi People,
>     does anyone know if there is a subsitute blower available or how 
> to quiet down this blower?
>     There is a problem on 15 meters(only) with not getting full 
> output. There is a big 10 ohm wirewound ceramic resistor in series 
> with the HV (connected in series with the plate RF choke), its mounted 
> in front of the blower input, the ceramic has flaked off one 
> side....any connection betwixt these ?

***  Probably not.  The wirewound resistor is for glitch protection.  
Flaking is usually caused by a +HV arc to ground -- either outside or 
inside the tubes.  If a moth or spider gets into the HV circuitry 
outside the tubes, there will be a bang.  If there's a gold-sputter arc 
inside a tube, very little noise will be heard.  Either event can cause 
a too-puny R to flake.  The fix is to reduce the V-gradient across the 
glitch-R by putting two such resistors in series.[note -- glitch 
resistors should be stout enough to survive a HV short to ground 
without any damage]   Another solution is to use a Globar 
surge-protection resistor (type SP) that can handle the # of joules 
stored in the HV filter caps.
--  As to the lack of power on 15m:  is the Tune-C at the limit when 
the amp is tuned for max out?  What is the anode/plate-I reading on 
15m?  thanks
>
cheers, John

Rich Measures, AG6K, 805.386.3734.  www.somis.org/

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