Problems With The NE602

Problems With The NE602

Post by Dan Westi » Fri, 29 Sep 2000 04:00:00

I've built a few oscillators around the NE602 and managed to
get the output from pin 7. But so far I have never been able
to get anything from either of the two regular outputs on pins
4 & 5. Can anyone tell me what I am doing wrong? Or what's
wrong with the chip?

Thanks.

 
 
 

Problems With The NE602

Post by Dan Westi » Fri, 29 Sep 2000 04:00:00


For a research project I need, in part, a RF source and an
inverted signal 180 degrees out of phase with the original;
the NE602 seemed liked the quickest and easiest way of doing
this without a lot of additional circuitry.

The book I had found some NE602 circuits in showed various
oscillator designs that could be implemented but never showed
how to get a signal from any of the mixer pins. A frustrating
condition since finding NE602s these days is a lot like
finding hen's teeth.



Westin"

>> I've built a few oscillators around the NE602 and managed
to
>> get the output from pin 7. But so far I have never been
able
>> to get anything from either of the two regular outputs on
pins
>> 4 & 5. Can anyone tell me what I am doing wrong? Or what's
>> wrong with the chip?

>> Thanks.

>But what are you trying to do?

>The NE602 is primarily a mixer, of the "Gilbert Cell"
variety, with a
>simple on-board oscillator.

>The oscillator is nothing more than a single transistor, if I
remember
>correctly.  It's intended for use with the mixer, and any use
of
>the device as only an oscillator is only incidental.

>I think pin 7 is the emitter of the transistor used in the
oscillator.

>Pins 4&5 are the outputs of the mixer.  Since it's a double
balanced
>mixer, there will be little or no output unless there is a
signal
>on the inputs of the mixer, pins 1 & 2.  A double balanced
mixer
>will not let the signals on the inputs feedthrough to the
output
>(though this is for the ideal mixer, in reality, there is
likely
>to be a little feedthrough).

>I don't see much advantage in using the NE602 as simply an
oscillator;
>if you just need such a thing, you might as well use a
transistor or
>two.  I suppose one could get the oscillator signal to appear
on
>the outputs of the mixer by unbalancing the mixer with some
DC voltage,
>but without the data sheet, I couldn't suggest exactly how.

>      Michael  VE2BVW

 
 
 

Problems With The NE602

Post by Michael Bla » Sat, 30 Sep 2000 12:03:50



> I've built a few oscillators around the NE602 and managed to
> get the output from pin 7. But so far I have never been able
> to get anything from either of the two regular outputs on pins
> 4 & 5. Can anyone tell me what I am doing wrong? Or what's
> wrong with the chip?

> Thanks.

But what are you trying to do?

The NE602 is primarily a mixer, of the "Gilbert Cell" variety, with a
simple on-board oscillator.

The oscillator is nothing more than a single transistor, if I remember
correctly.  It's intended for use with the mixer, and any use of
the device as only an oscillator is only incidental.

I think pin 7 is the emitter of the transistor used in the oscillator.

Pins 4&5 are the outputs of the mixer.  Since it's a double balanced
mixer, there will be little or no output unless there is a signal
on the inputs of the mixer, pins 1 & 2.  A double balanced mixer
will not let the signals on the inputs feedthrough to the output
(though this is for the ideal mixer, in reality, there is likely
to be a little feedthrough).

I don't see much advantage in using the NE602 as simply an oscillator;
if you just need such a thing, you might as well use a transistor or
two.  I suppose one could get the oscillator signal to appear on
the outputs of the mixer by unbalancing the mixer with some DC voltage,
but without the data sheet, I couldn't suggest exactly how.

      Michael  VE2BVW

 
 
 

Problems With The NE602

Post by Jim Wei » Sat, 30 Sep 2000 04:00:00


shared these priceless pearls of wisdom:

->For a research project I need, in part, a RF source and an
->inverted signal 180 degrees out of phase with the original;
->the NE602 seemed liked the quickest and easiest way of doing
->this without a lot of additional circuitry.

You chose a device that is intended to do precisely what you do NOT want it to
do, suppress the local oscillator at the balanced mixer's output.  The 602 is a
poor choice for this application.

Why not just tell us what you need and let us have at it?

Jim
Jim Weir, VP Eng. RST Eng.      WX6RST
A&P, CFI, and other good alphabet soup

 
 
 

Problems With The NE602

Post by Dan Westi » Sat, 30 Sep 2000 04:00:00

I am curious about how radio waves interact with each other in
the real world, not the mathematical one. So I intend to
produce four waves (somewhere in the LF to HF range) 0, 90,
180, and 270 degrees out of phase with each other and see what
happens on an empirical basis.

If I took a field strength meter and did this, would there
really be no reading-- or just reduced energy? Theory says
they cancel, but where does the energy actually *go?*

I also want to see what happens with minor variations that
result in intermediate cancellation that is neither totally
constructive nor destructive say four waves 0, 90, 180, 276
degrees out phase with each other. It's not ground-breaking
research, but there are some aspects of radio wave physics
that no one seems to have given any serious attention to that
intrigues me. Right now I am in "Phase Zero" part of the
research: just putting together the gear.



>shared these priceless pearls of wisdom:

>->For a research project I need, in part, a RF source and an
>->inverted signal 180 degrees out of phase with the original;
>->the NE602 seemed liked the quickest and easiest way of
doing
>->this without a lot of additional circuitry.

>You chose a device that is intended to do precisely what you
do NOT want it to
>do, suppress the local oscillator at the balanced mixer's

output.  The 602 is a
Quote:>poor choice for this application.

>Why not just tell us what you need and let us have at it?

>Jim
>Jim Weir, VP Eng. RST Eng.      WX6RST
>A&P, CFI, and other good alphabet soup

 
 
 

Problems With The NE602

Post by Harold Johnso » Sat, 30 Sep 2000 04:00:00

Try using a 74AC161. Feed a signal of 0 to +10 dBM to pin 2 (the clock) and
you'll get quadrature outputs at 1/4 the frequency at pins 11,12,13 and 14.

W4ZCB
(Ground pins 3,4,5 and 6, feed pins 1,2,7,9 and 10 decoupled 5 volts)

 
 
 

Problems With The NE602

Post by David Newkir » Sat, 30 Sep 2000 04:00:00


> I've built a few oscillators around the NE602 and managed to
> get the output from pin 7. But so far I have never been able
> to get anything from either of the two regular outputs on pins
> 4 & 5. Can anyone tell me what I am doing wrong? Or what's
> wrong with the chip?

The NE602 is a mixer/oscillator chip, and pins 4 and 5 are its mixer
outputs. The 602's circuitry is designed so that its RF input (pins 1
and 2) and oscillator signals "balance out" and are greatly attenuated
(by several tens of decibels) at the output of the mixer section. Only
the arithmetic sums and differences of these signals (and, at lower
levels, the sums and differences of their harmonics) should appear at
pins 4 and 5.

Best regards,

David Newkirk, W9VES

 
 
 

Problems With The NE602

Post by Martin Farrel » Tue, 03 Oct 2000 04:00:00



Quote:

>Try using a 74AC161. Feed a signal of 0 to +10 dBM to pin 2 (the clock) and
>you'll get quadrature outputs at 1/4 the frequency at pins 11,12,13 and 14.

>W4ZCB
>(Ground pins 3,4,5 and 6, feed pins 1,2,7,9 and 10 decoupled 5 volts)

---------------------------------------^?
Harold,
How can a counter give quadrature outputs? There's something you're not
telling us.
--
Martin G8ASG
 
 
 

Problems With The NE602

Post by Michael Bla » Wed, 04 Oct 2000 12:47:35





> >Try using a 74AC161. Feed a signal of 0 to +10 dBM to pin 2 (the clock) and
> >you'll get quadrature outputs at 1/4 the frequency at pins 11,12,13 and 14.

> >W4ZCB
> >(Ground pins 3,4,5 and 6, feed pins 1,2,7,9 and 10 decoupled 5 volts)

> ---------------------------------------^?
> Harold,
> How can a counter give quadrature outputs? There's something you're not
> telling us.

> Martin G8ASG

I can't quite picture what's going on in this case, but using dividers
to generate quadrature signals is not a new thing.

Certainly, it appeared in amateur publications almost as soon as logic
ICs became available to the hobbyists.  A lot of it was theoretical,
ie "one can even generate the quadrature signal by using dividers",
in articles about using the phasing system to generate SSB.  You can
do it with two type-D flip-flops, which I recall had some limitations,
and of course, the signal fed into it is divided by two.  Far more
common is another configuration where the  output signal is
divided by four.

Back in 1973 or 74, there was an article in Ham Radio about a phasing
type direct conversion receiver, using MC1496's as product detectors,
and ECL to generate the 90 degree apart local oscillator signals.  The same
author followed it up a year or so later, with a matching transmitter.
That may have been the first practical article in the ham press.

In more recent years, the idea may have become more visible, since
phasing has made somewhat of a comeback, with better ability to match
components (or perhaps better components?) and even with the use of
doing the audio phase shifting in digital.

Both my 1986 and 1993 Handbooks (the most recent I have) include the
details of using dividers to generate quadrature RF signals for phasing.
It's even in "Solid State Design for the Radio Amateur" by Wes Hayward
and Doug DeMaw published in 1977.

Don Lancaster even shows the circuit in his "CMOS Cookbook", though
he's not talking about phasing SSB.

I can picture an article in QEX a few years back about a Weaver/third
method SSB transmitter, and I can picture some sort of counter like
the 74HC161 being used to generate the needed phase-shifted signals.

      Michael  VE2BVW

 
 
 

Problems With The NE602

Post by Martin Farrel » Thu, 05 Oct 2000 04:00:00



Quote:>I can't quite picture what's going on in this case, but using dividers
>to generate quadrature signals is not a new thing.

Absolutely, it's just that I can't see how this one works at all. But if
it had done it would simplify the wiring of an AC74.
--
Martin
 
 
 

Problems With The NE602

Post by Harold Johnso » Thu, 05 Oct 2000 04:00:00




> >I can't quite picture what's going on in this case, but using dividers
> >to generate quadrature signals is not a new thing.

> Absolutely, it's just that I can't see how this one works at all. But if
> it had done it would simplify the wiring of an AC74.
> --
> Martin

Good Morning Gents. For whatever reason, I have not been able to send a
corrective post these last several days. My ISP has been extremely
uncooperative.

The answer is that it can't. Thank you Martin for catching me and I
apologize for the confusion I generated. I had built the Bedford radio and
used the Tayloe detector for the DC conversion. I used the 161 for a simple
squarer, and fed that to the Tayloe PISC 3253 which DOES make the quadrature
output. I spoke off the top of my head without reviewing the circuitry.
Sorry about that, and let's see if this miserable ISP lets my mea culpa onto
the newsgroup.

W4ZCB

 
 
 

Problems With The NE602

Post by Martin Farrel » Thu, 05 Oct 2000 04:00:00



Quote:> I had built the Bedford radio and
>used the Tayloe detector for the DC conversion. I used the 161 for a simple
>squarer, and fed that to the Tayloe PISC 3253 which DOES make the quadrature
>output.

Hello Harold,

You know I wondered if that might be the explanation. I built the
version in (SPRAT Vol101 G0BBL) in surface mount. It's tiny but with a
terrific performance.

--
Martin