Re: level and wave shape after balans mixer?

Charles Darley

Hi All
I rather agree with Mark - I have done a lot of construction in the past and the absence of such info takes a long time of searching for a fault.  AND It will make great testing and fault finding practice for my club members whilst I am building the project.
the question is how best to show it ...
I suggest a second schematic so that the first is used during construction and then the second during testing.  At the point where  a value wants to be put annotate with an arrow and letter and then list the information separately ..
Mark if you give me the info then I would happily try to do a suitable sheet and post it to the group fro discussion
Regards Charles

-----Original Message-----
From: Mark [mailto:Mark@...]
Sent: 01 July 2004 12:19
To: BITX20@...
Subject: [BITX20] Re: level and wave shape after balans mixer?

- 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" wrote:
> Thanks for the additional information.
> > the correct schmatics are now at
> I checked again and
> 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
> did I make the correct connections, is it really working the way
> 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
> comes
> > alive first.
> The receiver works, while connecting a wire to Q3 I hear a lot
> then with the wire connected to the mixer.
> > i am convinced that we need to add detailed test measurements
> 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
> 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
> with and without oscilator on (for every stage) will avoid the
> 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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