Hans Summers wrote:


NE602 front-ends are even simpler than SBL-1 front ends. Contrary to
popular belief in some circles, you can still get the NE602 in 8-pin DIP,
new, from Philips: the new name, for an improved part, is SA612AN. (The N
suffix means 8-pin DIP.)


I don't think it's exactly like that.

The NE602 was manufactured by Signetics. Philips bought Signetics in 1975
from its previous parent company Corning Glass WOrks. In 1991 Philips
Semiconductors became a separate company within the Philips group, and
Signetics was integrated into Philips Semiconductors in 1993 to give greater
product recognition in the US. From what I understand Signetics was aquired
from Philips in 1995 by the Keo Pyung (KP) Group, and subsequently
transferred to private ownership.

Anyway, a few years ago legend has it that there was a fire at a Signetics
semiconductor manufacture plant in Korea, destroying (amongst other things)
the master die and several year's worth of NE602 stocks. This is what gave
rise to the rumour amongst radio amateurs already hit by dicontinuation of
other mixers, that the NE602 had been discontinued.

In fact it hadn't, Philips continued production of the NE602 as part SA602.
Philips also offered a less expensive but slightly inferior equivalent, the
SA612. Later, a new manufacturing process was developed producing better
performance and reliability, and at the same time minor changes were made to
the SA602/612 circuit to improve performance. The new devices are part
numbers SA602A and SA612A. The N suffix is for 8-pin DIP, D suffix for 8-Pin
SO Surface Mount.

So, both the SA602A and the SA612A are still in production by Philips, the
602 being slightly superior to the 612.

Incidentally, despite the datasheet sating the internal oscillator can be
used up to 200MHz, I am having a lot of success using it in a VCO covering
range 140-300MHz. See some preliminary pictures of my spectrum analyser
project http://www.hanssummers.com/electroni...ctrumanalyser/.

Hans,

Looks interesting. Back in the early '90s I built a similar project,
described in Electronics Australia magazine some time in 1992. It used a
TV tuner as the front end and an NE602 as the converter, and displays
the signal on any old CRO.

Strangely, I only just got it out of hiding a few days ago and fixed a
fault with one of the rotary switches. It hasn't been used in many years
but I recently gave away my AM/FM tuner, and I remembered that this
Spectrum Analyzer has the neat ability to tune in and play FM radio,
which is why I bothered to get it going again.

It covers the ranges 88-108MHz, 138-225MHz and 470-870MHz which as you
can see is discontinuous. This is because of the tuner, but nowadays you
can get tuners that don't have gaps in their coverage.

Electronics Australia no longer exists, sadly; it closed in 2001 after
an illustrious 80 years or so, having begun as "Radio & Hobbies" in the
'20s. However, reprints of almost all articles are available from
http://www.siliconchip.com.au for about AU$10.00

Rob