Interesting Aerial Facilities PIN switch (?)

[wkb]

Found this cutie on a HAM fair here in PA country (the Netherlands). 

Manufacturer is Aerial Facilites Ltd, and it was hand marked as "70MHz" stuff.  Does anyone on this forum have any info on this beast?
I am curious about the 'coiled' interconnects between the chambers in the milled-aluminium box.  It looks like very thin semi-rigid coax.
Any clues?

tnx Wilko

[w2aew]

Those coiled sections could be 1/4 wave transmission lines, which could be used in switch applications for things like T/R switches.  I did a video of one such PIN diode based T/R switch (using lumped elements instead of a 1/4 wavelength line).  Here's the video on that, if you're interested:

[raspberrypi]

Great explanation answered all my questions too. Where do you buy the parts to make your inductors?

[langwadt]

Those coiled sections could be 1/4 wave transmission lines, which could be used in switch applications for things like T/R switches.  I did a video of one such PIN diode based T/R switch (using lumped elements instead of a 1/4 wavelength line).  Here's the video on that, if you're interested:

in NMR it is commonly done passively, basically the same circuit just skip the control and replace each diode with a set of antiparallel diodes

[w2aew]

Great explanation answered all my questions too. Where do you buy the parts to make your inductors?

I get a lot of my toroids from here: http://kitsandparts.com/ or here: http://qrpme.com/?p=product&id=PT