Post by thread:[EE] varactor diode 200pF

Try Part Miner ----- Original Message ----- From: "Vasile Surducan" <spam_OUTpiclist9TakeThisOuTgmail.com> To: "Microcontroller discussion list - Public." <.....piclistKILLspam@spam@mit.edu> Sent: Tuesday, May 29, 2007 12:28 PM Subject: [EE] varactor diode 200pF > I'm searching for a 200pF-300pF varactor diode with large capacitor > variation, at least 10 (something equivalent with MV1405). No luck at > Digikey or Mouser. > Any clue ? The RF guys are allive ? > > Vasile > --

Use a 1n5401 large area silicon not specked like this but it should work. I used 4001's for about 30pf varicap as FM modulators for pirate radio about 20 years ago they work fine. Effectively the bigger the diode the larger the silicon hence capacitance any 'big' rectifier will do Steve -----Original Message----- From: piclist-bouncesKILLspammit.edu [.....piclist-bouncesKILLspam.....mit.edu] On Behalf Of Vasile Surducan Sent: 29 May 2007 17:29 To: Microcontroller discussion list - Public. Subject: [EE] varactor diode 200pF I'm searching for a 200pF-300pF varactor diode with large capacitor variation, at least 10 (something equivalent with MV1405). No luck at Digikey or Mouser. Any clue ? The RF guys are allive ? Vasile

Vasile Surducan <piclist9 <at> gmail.com> writes: > I'm searching for a 200pF-300pF varactor diode with large capacitor Please try a large silicon transistor (like 2N3055T etc). I used such a device in an antenna tuner years ago. The advantage is that lightning is unlikely to damage it ;-). It should even work for transmit mode for QRP. 2N3055 can be biased up to about 80V so maybe it can reach your 1:10 range. The only real disadvantages are size and the capacitance curve not being anti-quadratic. The largest device I tested like this was a 'hockey puck' thyristor. It showed tens of nF capacitance with 9V bias. I never used it for anything varicap-like (it was too large and too expensive for this). Peter P.

Steve, Peter, thanks for the suggestion for using other junctions as varactor, I have used before the 1N4148 like varactor but don't have hyperabrupt characteristics.I have also some space constrain so a SMD package will be nice. Rich you had right, Partminer had it but I don't like to buy discontinued parts. I thought someone has a direct replacement suggestion. I'm building a clean sinusoidal output VCO (1-10MHz) and want other solutions than DDS (MAX8038 or other obsolete sinusoidal generators). thx, Vasile On 5/29/07, Peter P. <EraseMEplpeter2006spam_OUTTakeThisOuTyahoo.com> wrote: {Quote hidden}> Vasile Surducan <piclist9 <at> gmail.com> writes: > > > I'm searching for a 200pF-300pF varactor diode with large capacitor > > Please try a large silicon transistor (like 2N3055T etc). I used such a > device > in an antenna tuner years ago. The advantage is that lightning is unlikely > to > damage it ;-). It should even work for transmit mode for QRP. 2N3055 can be > biased up to about 80V so maybe it can reach your 1:10 range. The only real > disadvantages are size and the capacitance curve not being anti-quadratic. > The > largest device I tested like this was a 'hockey puck' thyristor. It showed > tens > of nF capacitance with 9V bias. I never used it for anything varicap-like > (it > was too large and too expensive for this). > > Peter P. > > > > -