Good pedagogical examples are worth remembering.
Check off your $100 word for this week.
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
On the principle that some performance improvements have been made in the past 46 years,
The way I understand it, Tektronix started making these relays because nothing of similar performance was available at the time and they actually ended up OEMing them for others. The claim to fame for the relays was how they were constructed with the switch sections immediately adjacent to the base for minimum parasitics; modern high performance small signal "telecom" relays use the same configuration and have similar performance.
Where Tektronix could, I think they replaced them simply for cost reasons either with their high performance cam operated switchs or by altering the circuit designs. Early 7000 plug-ins all used the relays but were quickly replaced by newer plug-ins which did not; the best example might be the 7A16 with 7 relays being replace by the 7A16A with no relays. Similarly the 7A12 was replaced by the 7A18.
In one way however, modern relays are worse. The Tektronix relays used a clever symmetrical pinout so the DPDT models can be turned 180 degrees and function exactly the same. Modern relays use an asymmetrical pinout as I discovered when trying to find replacements for the Tektronix ones.
searching Mouser for "RF Relays" leads to http://www.mouser.co.uk/Electromechanical/Relays/High-Frequency-RF-Relays/_/N-5g33/ That contains 1059 items with frequencies up to 8GHz. Looking at the datasheet for one of those indicates pulse risetimes <50ps, VSWR <1.1 f<1GHz, VSWR <1.05 f<0.5GHz.
There may be some standard cost-performance engineering tradeoffs to be made ![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
That is definitely the case and more. RF relays are a lot more expensive than "telecom" relays and being designed for a constant impedance environment, may actually work worse in something like a high impedance attenuator. I suspect miniature RF relays as we know them were also not available back then either; Tektronix used reed relays with a split coaxial shield instead and they perform well into the multi-GHz range. There are some good photos of them here:
http://w140.com/tekwiki/wiki/7T11