Since the KT76A isn't solid state, the cavity oscillator
tube is a costly replacement--near $1000 total--and you may face that if you keep this unit long enough.
A ruggedized sapphire cavity oscillator has been introduced, offering microwave designers and system engineers an exceptionally low noise X-band source in a system-ready package.
The technique was first perfected and is still used in the company's Sapphire Loaded Cavity Oscillator (SLCO) line of test instruments.
The model 88028-xxx Gunn cavity oscillator is one of six source available currently.
Here too, Gram cavity oscillators have the advantage in that the cost of these sources is substantially lower than their FET counterparts in production quantities.
A film of Kapton(*), a polyimide film used for DC isolation purposes in metal cavity oscillators
, is sandwiched between these two parts, so as to isolate them for each other as seen from the bias source.
[21,22] It is also the case that the spectral purity of quasi-optical oscillators can be higher than that of waveguide cavity oscillators
using the same devices.