[TenTec] Herc II idling collector current adjustment

[Phil Chambley, Sr.]

Ken...

Your meter is indicating a static current flow that, by measurement, you
don't have.  That means one of the meter amplifiers on the distribution
board (or U5) is leaking.  You can learn which one by removing the power
leads to the amplifiers one at a time and see which one causes the mid-scale
quiescent current to disappear.  Then change that op amp out.  They will be
LM301 or 358.

Also, once it begins leaking badly enough, the power supply will begin
tripping out.  This is because the trip circuit can't tell if the current
draw is real or perceived.

Phil
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----- Original Message ----- 
From: "Ken Brown" <ken.d.brown at verizon.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Monday, February 21, 2005 5:59 PM
Subject: Re: [TenTec] Herc II idling collector current adjustment


> I only see a U1, U2 and U3, all LM358N. There is a non-zero DC input on
> the + input of U3, with the amp on and not keyed. So I think that the DC
> offset may be coming from U1 or U2. I would replace them all if I had
> them handy.
>
> Hey, check out R22 a 100 ohm resitor to ground on one ouput of U1! None
> of the other outputs have one. Shouldn't it be connected to the opposite
> end of R35? to make the load on all of the opamps and zero ohm resistors
> the same?
>
> > While you've got it opened, though, you might consider
> >changing out U5 on the distrib board.
> >
> >
> >
> >
>
>
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