Way back in the late 1980s, freshly out of engineering school, I
was working as an RF engineer at the General Electric Aerospace Electronics Division
(GEASD) in Utica, NY. I was tasked with designing a small switched filter/amplifier
for part of an airborne electronic countermeasures system. At the time, I was new
to the RF design world, even though I had spent a lot of years working on RF systems.
So, I set about researching components from MIL-qualified vendors.
Watkins Johnson, Narda, Amplifonix, and many other companies published
really nice catalogs in those days that were chock full of application note. Most
app notes are found today on the Internet rather than in data books, which is of
course not only more convenient, but saves a lot of cost for printing and distributing.
Up until the mid-to-late 1990s, manufacturer's catalogs were actually used rather
than just being tossed into the recycle bin when they arrive in the mail.
As anyone who has been in the RF business for a while knows, jokes are always
made about how anything and everything can - and will - affect the performance of
high frequency circuits if proper precautions are not taken. Statements like, "Gain
will be 10 dB nominal, with variations depending on the time of day, stock market
levels, and the phase of the moon." Well, the engineers at Watkins Johnson actually
managed to pull off getting a gag plot into the 1989(?) catalog for their WJ-G1/SMG1
voltage-controlled attenuator. It is shown below. Do you remember seeing it?
Thanks to Joe
Cahak, of Sunshine Design (click logo at right) for providing a scan of the catalog
page. Joe worked for WJ at the time, and is now a independent consultant with 25
years of experience.
Watkins-Johnson WJ-G1/SMG1 Voltage-Controlled Attenuator Datasheet
with Phase vs. VCTL vs. Frequency vs. Phase of the Moon Chart.
Featured Product Archive
The inventions and products featured on these pages were chosen either for their
uniqueness in the RF engineering realm, or are simply awesome (or ridiculous) enough
to warrant an appearance.
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November 2018 Update
RF Cafe visitor Paul Johnson (no relation to the "J" in WJ) sent the following
I just came across my WJ 25 year coffee mug and thought I'd look up Watkins-Johnson
to see if they were still around and how they were doing. Then I remembered the
Phase of the moon data sheet and thought I'd look that up too. That brought me to
you RF Cafe site.
It was cool to see the data sheet again but I'm not sure where you got 1989 date
from. When I was with WJ in 1982-83 it had already been in the catalog. Also at
the time it came out management was not amused (A lot of the employees were). The
story goes that an engineer slipped it in for submission expecting it to get caught
before publication. Needless to say it didn't.
The catalog did get a lot of attention. Perhaps it was reprinted on purpose in
1989 as a nostalgia thing.
In any case it was kind of neat to see.
Also, don't forget the Signetics 25120 Fully Encoded, 9046 n N, Random Access
Write-Only Memory datasheet. While you're wasting time, you might
as well see the "slightly tentative data" for
WEMAC- The One Zed Two Zed Vacuum Tube that was purportedly the
inspiration for the Signetics 25120.
There is also a "Delayed
Light Turn-Off" circuit in the 1973 Signetics 555/556 timer databook that uses
a firecracker and a calibrated rock to snuff out a candle flame after a prescribed
Posted September 15, 2015