Re: level and wave shape after balans mixer?

Mark <Mark@...>
 

- farhan wrote:

i am convinced that we need to add detailed test measurements for the
transceiver on the site. i have most of them in my log book. i will
post them soon.

I would welcome test measurements - two days of head scratching so
far! The RX is alive in my rig but not yet kicking! I have a lot of
BFO audible in the output also I have had to bypass the xtal filter
and the band pass filter to get any signal strength.

I'll tell you all this story just for fun. I had no joy with the
band pass filter and nearly threw the rig out of the window. Then I
realised that when I had "made" 2.2 pm out of 5 x 10pf caps I had
them in parralel and not series! Oh boy, the basic mistakes!

I try some more tomorrow.

Mark G0MGX



--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:
Thanks for the additional information.

the correct schmatics are now at www.phonestack.com/farhan.
I checked again http://www.phonestack.com/farhan/bitx.html and
found
out that point 5 and 6 are stil wrong (not in accordance with the
data sheet, as noticed and posted by someone else).
I connected it correctly but an other person that follows the
schematic can have serious problems.
(if you make adjustments to your site, may be you can also add a
link to this yahoo group?).

The point is that I expected more output after the mixer. I am
always suspicious with that kind of coils (did I take the right
one,
did I make the correct connections, is it really working the way
it
should be) so I like to check something.

if you have already made the crystal filter, it is best that you
measure
and check the signal at the output Q12 (without the RF mixer
connected).
I will work on it today and add directly the next stages to
terminate the filter as good as possible. I hope the output will
then be incresed some more otherwise I do not end up with enough
power at the end (or am I pessimistic ;-) ).

have you tested the receiver yet? it is usually the recevier
that
comes
alive first.
The receiver works, while connecting a wire to Q3 I hear a lot
more
then with the wire connected to the mixer.

i am convinced that we need to add detailed test measurements
for
the
transceiver on the site. i have most of them in my log book. i
will post
them soon.
In general, voltages can be checked easily to find out roughly
that
the connections are correct and the correct values resistors are
mounted. Some general clues about what can be expected while
connecting a wire to a point or what voltage can be measured with
simple test gear would make it more complete indeed. May be
current
with and without oscilator on (for every stage) will avoid the
need
for more test equipment?
Adding too many measurement possibilities may be prevents a lot of
people building the design because they think it is all needed.
Doing the way you do now makes it important for everyone to
understand the circuit resulting in a higher level of radio
amateurs ;-)

Other builders comments?
Best regards,
Chris, PA3CRX

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