Right there in figure 9 is the signal generator page 5 of the pdf. Electronics Now Feb 1997

sometime later
I see figure 9 in the Austrailian magazine Elektor 1992.

Joseph Carr must have been limited by copy right from 1992
There is a universal break out board shown in Elektor never seen the assembly or completed project or review.

Anyone know anything about the hobby magazine signal generator application using a double balanced mixer IC ?

 

Two references to articles in hobby magazines over 20 years old? And what part of a signal generator would a double balanced mixer be???
That is probably a reference to that analog multiplier IC that was a mature product on that era. There is a fair amount of information available in older texts about that IC, but I am not sure if it is even still available.
But if you are seeking information about that universal break-out board, there are others available, I am sure.

 

There are 3 ICs in that series, all of them 4-quadrant multiplies. And one application note shows it used as a multiplier. So it was probably part of the waveform modulation scheme.

 

I should have mentioned it was AM, and low bands. Wondered if Carr's generator would rate along side the 8038 and XR2206 on Sinusoidal.
the article in Elektor figure 9 being the correct article mentioned 5 years later there is more from Carr on simple sine wave generator.
The magazine articles are abbreviated from one of his many books. "Secrets of RF circuits" chapter 10 page 244. by trailing his work
On page 250 Signal generator for the AM and shortwave bands and figure 10-7

I have ok designs like this on simulator but they do not have the best feedback, it has been rumored that the THD could be lowered from 3%
I thought it was due to balanced mix the NE602 (ref pp below figure 10-9) but he also uses 217uH primary inductively coupled. He mentions a Toko digikey part number. Since he was good at inductive coupling I think everything he shows in some way related to getting this correct.

The goal has been to find a low cost variable sine wave generator for educational use, for hobby enthusiast.
Is it the inductor's coupling factor or balance, better symmetry or filtered feedback not sure what explained but It is still a secret.
Maybe an op amp would improve it. An active LP Filter .

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjQnKGNpqTtAhWOvJ4KHXmHBgsQFjAAegQIAxAC&url=https://pdf4pro.com/cdn/chapter-432deb.pdf&usg=AOvVaw1pdLqkX3cUul8Kvu3fnWvb


NE602 data sheet has a basic Colpitts
https://www.nxp.com/docs/en/data-sheet/SA602A.pdf

 

With oscillators there seems to always be a problem of fast starting versus low distortion, and unfortunately many of the ways that very rapid startup is assured also tend towards a lot more distortion. Bill Hoisington, another writer, pointed out that more gain and less feedback tended towards a better waveform. Higher "Q" in the resonator along with some means of amplitude control that avoids distortion tend to avoid producing harmonics.
The tradeoff is always complexity, and in comercialy produced equipment that always adds to the cost. At least it seems that way.
And one unasked question is about the intended frequency range, min-max frequency ratio, and just how pure a sine wave really is needed, or wanted.