[Amps] L4B Caution

[Dave Knight]

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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