[Amps] L4B Caution

[Paul Baldock]

True, but most people like you modify them for 
diode bias and auto resistor bias cut off.

- Paul

At 01:26 PM 7/25/2013, Dave Knight wrote:
>I thought it also provided bias for the 
>tubes.  I used the sting of diodes on mine.  I got help from VE7RF.
>73
>Dave N4XYZ
>
>Sent from my iPad
>
>On Jul 25, 2013, at 3:24 PM, Paul Baldock <paul at paulbaldock.com> wrote:
>
> > Yes, I forgot about alc, which I also don't use.
> >
> > - Paul
> >
> > At 11:52 AM 7/25/2013, Jim W7RY wrote:
> >> And provide the ALC voltage. If you don’t 
> use ALC (which  I don't) then you can remove them.
> >>
> >> 73
> >> Jim W7RY
> >>
> >>
> >> -----Original Message----- From: Paul Baldock
> >> Sent: Thursday, July 25, 2013 10:41 AM
> >> To: Ed K0KL ; amps at contesting.com
> >> Subject: Re: [Amps] L4B Caution
> >>
> >> I suggest you remove the bleeder resistors. They serve no purpose
> >> other than to speed up the bleed down when you turn the amp off. They
> >> create a lot of unnecessary heat in the supply.
> >>
> >> - Paul   KW7Y
> >>
> >>
> >>
> >> At 10:32 AM 7/25/2013, Ed K0KL wrote:
> >>> I had a bad experience when working on an 
> L4B for a pal. The bleeder resistor mounting
> >>> scheme proved to be a little poor (unusual 
> for Drake). When reinstalled, one of the resistors
> >>> shorted to the mounting screw.
> >>> This bleeder is held in place by a screw 
> that goes through the center of the resistor. Mica slices
> >>> insulate the ends (chassis and screw head). 
> Only thing is the resistor arced through the ceramic
> >>> base material. So I used glass tape to 
> insulated the screw on the reinstalled components. This
> >>> provided better spacing to the center of the screw.
> >>> Note- I replaced the resistors, having the 
> same thing reoccur. Only with the use of the tape did
> >>> the thing calm down. Ordinary electrical 
> tape won't work as it will melt caused by the heat of
> >>> the resistors.
> >>>
> >>> Anyway, that was some time ago, the amp is 
> going strong. Except for a rather weak plate
> >>> transformer, this puppy will no doubt last several lifetimes.
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