Also keep in mind that the AC-4 doesn't have any extra HV current capacity when used with a TR-4, so excessive bias setting means not only wasted power but potential power supply damage.
regards, Mahlon - K4OQ > > From: "Russ Hines" <[EMAIL PROTECTED]> > Date: 2004/06/07 Mon AM 09:48:17 EDT > To: "gary livingston" <[EMAIL PROTECTED]> > CC: "Drakelist" <[EMAIL PROTECTED]> > Subject: Re: [drakelist] TR-4 > > Hi Gary: > > The idle current is adjusted to set the operating point of the finals. > Higher current means it's operating more toward the Class A region than > Class B. It makes the amp more linear but less efficient. We want good > linearity but better efficiency than Class A. We're shooting for Class AB. > > I'd readjust it to 100mA, just because I'm a stickler for such things. And > because that bias supply is used in the VOX and AGC circuits (I think that > applies to the tr-4). Anyway, your transmitter would likely work okay at > 150mA, but you might notice a drop in efficiency and/or power output. > > I'd also keep an eye on the current, it could be an indicator of some > soon-to-fail component. Or the bias adjust pot is just dirty. Your AC-3/4 > provides unregulated bias so if your AC line voltage varies a bit, so will > your bias supply. > > Good luck and have fun with your Drake. > > 73, > Russ > WB8ZCC > > > > > ----- Original Message ----- > From: gary livingston > To: [EMAIL PROTECTED] > Sent: Monday, June 07, 2004 8:22 AM > Subject: [drakelist] TR-4 > > > Hello Drakelist; My TR-4 is working great. However when I got it last week > the ideling current on transmit was at .15 mils. The book says to set it at > .1 mil which I set it at. Is there any reason why it would be better to have > it ar .15 mils? Thanks Gary WA0MYH > >
|
Hi Gary:
The idle current is adjusted to set the
operating point of the finals. Higher current means it's operating more
toward the Class A region than Class B. It makes the amp more linear but
less efficient. We want good linearity but better efficiency than Class
A. We're shooting for Class AB.
I'd readjust it to 100mA, just because I'm
a stickler for such things. And because that bias supply is
used in the VOX and AGC circuits (I think that applies to the
tr-4). Anyway, your transmitter would likely work okay at 150mA,
but you might notice a drop in efficiency and/or power output.
I'd also keep an eye on the current,
it could be an indicator of some soon-to-fail component. Or the bias
adjust pot is just dirty. Your AC-3/4 provides unregulated bias so if
your AC line voltage varies a bit, so will your bias supply.
Good luck and have fun with your
Drake.
73, Russ WB8ZCC ----- Original Message -----
From: gary
livingston
Sent: Monday, June 07, 2004 8:22 AM
Subject: [drakelist] TR-4 Hello Drakelist; My TR-4 is working great. However
when I got it last week the ideling current on transmit was at .15 mils. The
book says to set it at .1 mil which I set it at. Is there any reason why it
would be better to have it ar .15 mils? Thanks Gary
WA0MYH
|
