Re: [drakelist] TR-4

[Russ Hines]

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