Allison
Free Schematic CAD software that should run on your Microsoft NT-4.x can be
obtained via the following URLs:
All of these sites provide freeware schematic drawing software for windows
(and for Linux) that would be suitable to use in drawing a partial schematic
for the changes you have made in the BITX design. Of these three, EagleCAD
from CadSoft is probably the closest to a professional CAD program, but the
other two are certainly adequate and may be easier to learn.
And...Yes, there are other schematic drawing programs available. These are
just the ones that I know about and use frequently.
Arv K7HKL
_._
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On Thursday 28 July 2005 09:52 pm, ajparent1 wrote:
The best I can do would be jpeg photo of hand drawn paper page.
Even that takes some effort as only one PC supports USB and this
is not that one.? All my schematic capture cadd stuff runs on
VAX/VMS and is generally incompatable with PCs.
I may add the change is not very big.? I just turned the circuit
around to reverse the LO and IF ports. The transformer T3 feed
IF and Q9 feeds the balance pot through the .1uF cap.
If there is a prefered PC schematic capture I may investigate
but it must run under NT4 on a slow machine as this box is
generally accessable.
Allison
KB1GMX
--- In BITX20@..., Arv Evans <arvevans@e...> wrote:
> Allison
>
> Would it be possible for you do a quick schematic of the changes and
store it
> in the FILES section of this forum?? That way it will be available
for others
> who might not understand all that was changed from just the textual
> description.
>
> Thanks,
>
> Arv K7HKL
> _._
>
> On Thursday 28 July 2005 09:20 pm, ajparent1 wrote:
> >? One of the things I didn't like in the 20m proto BITX I'd built
> >? was the presence of audio getting into the IF amp on transmit and IF
> >? noise in to the audio on recieve.? I'd gone the route of adding an
> >? 47uh RF choke from the intersection of the balance pot wiper to
ground
> >? which helped greatly.? However, it always bothered me.
> >
> >? So I opened it up and tried a design change that I find pleasing and
> >? also elimiates a number of components.? As an engineer I'm the sort
> >? that looks at a design and says "what if..?".? The solution was
> >? staring me in the face and also eliminates the PI attenuator as well.
> >? The change is to turn the balanced modulator around and feed the IF
> >? in on the transformer and RF (bfo) in at the balance potentiometer
> >? via the .1uf capacitor.? This eliminated the need for the 3 resistors
> >? and the rf choke.? I noted cleaner modulation, less RX noise and more
> >? gain available in both RX and TX.
> >
> >? Might as well add this mod to the collection.? I plan to use this
> >? mod in the 6M version.
> >
> >? Allison
> >? KB1GMX
> >
> >
> >
> >
> >
> >
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