[Amps] L4B Caution
Jim W7RY
w7ry at centurytel.net
Thu Jul 25 14:52:18 EDT 2013
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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