Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
The amount of tuning that can be obtained by any of methods can reach up to +-20% of the unperturbed value of f0, however, it is good practice to restrict this amount to below 5% in order to prevent degradations on both temperature coefficient and unloaded Qs.
In a good DRO oscillator, the dielectric resonator determines the free-running frequency. A rough tuning is done by a conductive or dielectric post on a screw on resonator axis. Varying the distance varies the frequency.
Replacing the transistor by the same type can move the oscillator frequency by less than 5%. There are other factors like DR coupling in the feedback loop, tuning varactor coupling, etc. You did not say what is the oscillator frequency. If it is 20 GHz, a 1 GHz change is possible.
I replaced transistor by other type. What can i do to restore original frequency? Glue some metal plate near DRO's top? or maybe some dielectric on feedback line?
Signal loss in band-pass filter after oscillator, welding copper line above filter gives good signal, but wrong frequency. I think band-pass filter is just for DC-blocking, maybe i can remove it without harm for new transistor?
you can use a tuning screw over the top to adjust the frequency slightly. You can put a few drops of epoxy on top of the puck to lower F, and grind away a little material off top to raise F.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
