Is the ALC voltage not derived by a capacitive divider and diode from the
drive voltage at the cathodes?
The +120V for cut off bias coming from the bleeders are switched away by the
PTT relay.
73
Peter
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim W7RY
Sent: Donnerstag, 25. Juli 2013 20:52
To: Ed K0KL; amps@contesting.com; Paul Baldock
Subject: Re: [Amps] L4B Caution
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@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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