WJ-G1/SMG1 Phase vs. V_CTL vs. Frequency vs. Phase of the Moon

Cool Product Report

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. V_CTL vs. Frequency vs. Phase of the Moon Chart.

November 2018 Update

RF Cafe visitor Paul Johnson (no relation to the "J" in WJ) sent the following info:

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.

Best Regards.

Paul Johnson 

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 delay time.

Posted September 15, 2015