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I've been reading the ADF4351 datasheet and app notes and cannot figure out if one can sweep one output while holding the other constant. Does anyone know from experience? My impression from the diagram is that the two outputs must be fractionally related. Sweeping from 2 - 4.4 GHz with one output and 2 GHz on the other plus a couple of LPF filters to eliminate the harmonics ahead of the mixer seems as if it would serve nicely. A 2nd ADF4351 is about $15 USD, so not a major increase in cost if A & B can't be set separately. Running the output of a 100 MHz clock through a < 1ns logic chip and filtering out a single harmonic may or may not be cheaper in the long run. Reg On Friday, August 18, 2023 at 11:53:00 PM CDT, Daniel Ricardo Perez via groups.io <danyperez1@...> wrote: Erik, Thank?you?for?your?comment!?That's?exactly?what?I?intended?to?do,?except?I?was?aiming?at?higher?frequencies.?Even?though?this?is?a?very?basic?approach,?after?many?web?searches?I?found?only?these?three implementations: - This?is?the?one?I?am?attaching,?from?a?Romanian?magazine,?found?thanks?to?being?republished?by?Iulian?Rosu?YO3DAC/VA3IUL.?Anyway?I?distrust?it?a?little?because?of?no?buffering?between?VCOs?and?mixer,?I?fear?about?injection?locking?of?the?VCOs?at?certain?harmonics?combinations. - Ukranian design up to 250MHz, little info. Also no buffering. - This seemed interesting because the author began talking about experiments with VCOs with maximum possible frequency, but ended up using Minicircuits units (forget about purchasing Minicircuits here), and the project is incomplete. I have the UHF section of an old Zenith TV tuner, covering about 500...900MHz, the special thing about it is it uses a discrete transistor, the idea would be to downconvert to 0...400MHz. Also a Jerrold 400 cable box, also a piece of museum. I guess it covers about 50...400MHz upconverting to ~500MHz using a discrete DBM. A possibility is to inject a 500MHz signal at the output, and extract 0...350MHz at the input. But if someone else has a tried-and-true design, that will save me effort. Daniel LW1ECP El?viernes,?18?de?agosto?de?2023,?13:51:35?ART,?Erik?Kaashoek?<erik@...&²µ³Ù;?±ð²õ³¦°ù¾±²ú¾±¨®:
This?is?what?I?did?before?building?the?tinySA Build?two?single?transistor?oscillators,?one?on?fixed?100MHz?and?other?variable?100MHz?to?200?MHz?using?a?varicap Triangle?steering?of?the?varicap?done?using?two?opamps?and?three?potmeters?for?speed,?span?and?center Send?both?to?a?mixer?made?from?two?torroids?and?4?diodes Output?of?the?mixer?through?a?dyi?low?pass?filter?at?75MHz Frequency?verification?and?scale?calibration?done?using?an?FM?receiver?and?a?cheap?all?band?shortwave?receiver Verification?of?the?low?pass?filter?can?be?done?using?the?sweeper?and?any?form?of?power?detection?at?100MHz?(FM?receiver?) Voila,?a?simple?but?clean?sweeper?from?0-75MHz |
