Re: SoftRock40 Lite ... a bit deaf
- Thanks Chris ... I'm a great believer in home-brew gear. The kk5na
website design looks intersting and I'll probably look into that one
as I build up my amateur radio test gear again after a very long break
All the best ... Tom GM4DOZ
--- In email@example.com, Chris Albertson
> --- natsystems <tom@...> wrote:
> > Hi Tony ... thanks for your reply.
> > I'm afraid I don't have equipment that would allow me to measure the
> > receiver sensitivity, all I have is a good multimeter and an old'ish
> > oscilloscope.
> I also have an old scope too that is worthless as a measurement device.
> Calibration is off by more than 10X. and all the traces run down hill.
> You can build an RF voltmeter for about a buck.
> The trouble is the diode detector is not linear. The one
> below uses a matched diode to compensate for the detector.
> Chris Albertson
> Home: 310-376-1029 chrisalbertson90278@...
> Office: 310-336-5189 Christopher.J.Albertson@...
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> Tired of spam? Yahoo! Mail has the best spam protection around
- At 09:20 07/05/02, [softrock40] Digest Number 1723 wrote:
> Posted by: "natsystems" tom@... natsystemsTell us what sort of "pulse signal" you were expecting and we may
> Date: Tue May 1, 2007 9:52 am ((PDT))
>I then measured the input side of U5 on pins 2 & 6 and these are
>sitting at 2.5v DC. I would have thought I should have seen some form
>of pulse signal on these pins?
be able to tell you whether you should (or more likely, should not)
be seeing it.
Otherwise, it is difficult to fathom what your reasoning might be.
The SoftRock is a version of the Tayloe QSD, which is very well
documented elsewhere, and does not (unless it is demodulating
a pulsed signal) have a significant pulse waveform output.
Also, you are measuring at an op-amp virtual ground, so you would
be very lucky to see much baseband signal at all. If you really want
to see that signal before the op-amp, you should view it on the
source side of the input resistor, i.e. across C11 or C13, which
conveniently provide low-impedance and RF-decoupled test points.
[And please trim your quotes - it shouldn't be necessary to quote
your query and all its replies - just the immediately relevant bits.]
From Yahoo! Groups Help: ... trim all the irrelevant quoted text
out of your message (as a courtesy to the other members of
the group to make the digest easier to read).
- Hello Len .. see below ...
> Tell us what sort of "pulse signal" you were expecting and we mayI had expected to be able to see some form of quadrature output
> be able to tell you whether you should (or more likely, should not)
> be seeing it.
signal from U4, but given my lack of experience, perhaps my question
should have been: "what should I expect to see on the OP Amp input
> The SoftRock is a version of the Tayloe QSD, which is very wellI'll look to see what I can find on the net about the Tayloe QSD and
> documented elsewhere, and does not (unless it is demodulating
> a pulsed signal) have a significant pulse waveform output.
hopefully in future be able to sound more clued-up when required.
> [And please trim your quotes -And I do apologise to all for not sticking to etiquette with my
In any case Len, your advice on an approach for actually locating the
problem would be greatly appreciated. 'At this time' I am much more
intersted in just getting the unit to work, rather than having to
understand in detail how it works.
Cheers .. Tom.
- --- In firstname.lastname@example.org, "natsystems" <tom@...> wrote:
> Hello All ...
> I'm new to this group and everything SDR so I know you'll go easy
> I've built an SR40 Lite kit and it is definitely receiving but
> deaf. I can say that it's deaf because I've compared it to anotherone
> that a friend of mine built, and there's a bit output differencebeen
> between them.
> Since I can hear faint transmissions, and due to the board having
> checked out in detail by myself and someone else for potentialerrors
Tom, since you are receiving "faint transmissions", I am thinking
that U4 and U5 are ok and there is a problem with T1. I am an
experienced builder and I had some difficulty "decoding" the
instructions for the winding and insertion arrangement. I thought
about it awhile and finally soldered it in. Fortunately, it worked
straight-away (MDS about -120 dBm) but I could just as easily have
chosen the wrong arrangement. (Old age may have caused much of my
my $.02 73
> Tom, since you are receiving "faint transmissions", I am thinkingHi Sid ... I appreciate your $.02 worth :)
> that U4 and U5 are ok and there is a problem with T1. I am an
> experienced builder and I had some difficulty "decoding" the
> instructions for the winding and insertion arrangement. I thought
> about it awhile and finally soldered it in. Fortunately, it worked
> straight-away (MDS about -120 dBm) but I could just as easily have
> chosen the wrong arrangement. (Old age may have caused much of my
> my $.02 73
> Sid W7QJQ
I too was suspicious of T1 and I went as far as re-winding a new one
and very carefully following the instructions - and may I add, under
guidance from a friend who also checked it out! I have to say
that "as far as I can be sure," I think that T1 is okay now. The
other thing I'm dealing with here is that I've now lost any ability
to receive even faint transmissions, so it would appear that the
fault has crept in gradually. Despite what's been said previously, I
can see a signal on the input pins of the OP Amp (2&6) on a good
working unit, but I can't see any hint of a signal on the faulty
unit. I'm forced now to think that I need to take the plunge and
replace either U4 or U5.
As I said Sid, thanks for the donation!
73's ... Tom GM4DOZ