[Ronja] nebulus test points don't match

[mohamad al-jamal]

it's a simple , genius solution ! thanks a lot .

On Mon, Aug 3, 2009 at 9:58 AM, Gullik Webjörn
<gullik.webjorn at corevalue.se>wrote:

> Put one or two diodes in series with the zener, each diode
> will give you 0.6-0.7 V, i.e. 6.2 + (2*0.6) = 7.4.
> Any small si diode will do. (check correct polarity!)
>
> Gullik
>
>
> On Sun, 2009-08-02 at 19:58 +0300, mohamad al-jamal wrote:
> > thanks a lot , that was really helpful , i think where my problem is ,
> > the zener i used isn't neither 7.5 nor 7.3 , it's 6.2 !! my supplier
> > has gived me the wrong zener . as for P6 , actually now it reads
> > 4.96 . the previous reading - the wrong one = 4.21 - was due to
> > misplacing the prope of my multimeter .
> > so everything adds up now .now my question is : will my nebulus work
> > with this zener ? fiding the 7.5 wasn't easy !!
> >
> > On Sun, Aug 2, 2009 at 2:20 AM, Gullik Webjörn
> > <gullik.webjorn at corevalue.se> wrote:
> >
> >         On Sun, 2009-08-02 at 01:17 +0300, mohamad al-jamal wrote:
> >         > come on guys , i need help here
> >         >
> >         >
> >         > On Sat, Aug 1, 2009 at 2:28 AM, mohamad al-jamal
> >         > <mohammadaj at gmail.com> wrote:
> >         >         Hi
> >         >
> >         >         I've just finished building my nebulus Tx ,
> >         following the
> >         >         exact instructions in the guide to the last detail ,
> >         except
> >         >         for the zener , where i used a 7.3V instead of 7.5
> >         >         as i couldn't find one  . but the "DC - no signal"
> >         test points
> >         >         didn't  match , i rechecked the connections , and
> >         tested the
> >         >         parts before placing them , and afterwords,
> >         >         but there are differences , 1.3 V for P7 for
> >         example !! here
> >         >         are my results :
> >         >         P1   1mV
> >         >         P2    5.55 V
> >         >         P3    4.88
> >         >         P4    5.58
> >         >         P5    9.88
> >         >         P6    4.21
> >         >         P7    5.00
> >         >         P8    0
> >         >         P9    1mV
> >         >         any help is highly appreciated
> >         >
> >         >
> >
> >
> >                P1 = 1 mV ?? Do you have a proper AUI connected at coax
> >         input?
> >                P2 = 5.55 V, well, 7.3 - 0.7 = 6.6V, do you have 7.3 at
> >         D2?
> >                P3 = 4.88 V, well 5.55 - one VBE 0.7 V, seems OK
> >                P4 = 5.58 V, derived from P2, higher than P2 ???? with
> >         or without
> >         signal ??
> >                P5 = 9.88 V, reasonable, 9.88n - 4.88 = 5 V over Q2 VCE
> >                P6 = 4.21 V, I should have expected same as P7,
> >         something taking
> >         current, broken IC U1, U2 or U3???
> >                P7 = 5.00 V, 7.3 - 1.4 ( 2 * VBE) = 5.9, a little low,
> >         how much current
> >         does nebulus take?
> >                P8 = 0, very reasonable with P6 at 4.21 V
> >                P9 = 1mV, well, if P8 is at 0, then P9 should also be 0
> >         V,
> >                        since P9 is voltage drop over R17, and with no
> >         voltage
> >                        out of the driver ICs you do not get any
> >         current, thus
> >                        no voltage drop.
> >
> >         In all, your circuit looks good, BUT, it looks like your U1-U3
> >         are
> >         taking input current, which they should not, (P6=4.21 V) so
> >         maybee you
> >         broke one of them. I would have expected P6 = P7 (+/-) 50 mV,
> >         with no
> >         signal. IF you have a signal, the difference might be OK,
> >         depending
> >         on signal duty cycle....
> >
> >         So, with input signal disconnected P6 = (almost) P7, WITH
> >         signal
> >         lower, i.e. 4.21 V might be OK.
> >
> >         Hope this helps
> >
> >         Gullik
> >         >
> >         >
> >         >
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