7482Re: [softrock40] PIN Diodes
- Dec 3, 2006Tilman,
Jo - Handboken har varit till stor hjälp när jag först ville börja pula med
Kul att den finns allmänt tillgänglig på nätet.
On Sunday 03 December 2006 12:57, Tilman D. Thulesius wrote:
> I found the "pinhandbook.pdf" on teh net here:
> Looks interesting I must say.
> / Tilman SM0JZT
> > Pin diode switches are as reliable ( more reliable! ) as manual
> > switches if
> > designed properly!
> > You can use power pin diodes for bandpass switching in the PA but the pin
> > diodes are more often used in low power applications.
> > I tested some pin diodes in a SoftRock receiver and replaced the FST
> > switch
> > chip with pin diodes instead. It works all right but I was not able to
> > achieve the switch times I wanted so I use USB High speed switches
> > instead.
> > If you want a fast switching time and to ensure that no RF feedback
> > triggers
> > the diodes, you have to drive them hard. Doing so, may create problems on
> > very high frequencies due to inductance but hey! on HF bands? Naaah!
> > Using pin diodes for switching of the input bandpass filter and for a
> > QRP PA?
> > Good idea and it works absolutely fine.
> > HOWEVER! Please refrain from taking a dive in your junk box!
> > Buy new types and with the voltage spec you requires. For clamping, I
> > normally
> > use the BAT60A as it's a very low voltage drop diode ( 0.1 to 0.3V -
> > BUT! a
> > Ct of 20pF ) as well as suitable for QRP PA's.
> > For serial switching, I use almost any other pin diode like the
> > HSMP-3894-BLKG
> > ( a Ct of 0.21pF ).
> > On lower frequencies, the "leakage" from a 0.21pF Ct, is not a problem
> > normally. You will probably have more stray capacitance from a sloppy PCB
> > design anyway...
> > There are a good document to be found on the internet -
> > pinhandbook.pdf, but I
> > don't remember where I found it or if it's allowed to be copied to the
> > public
> > domain. Mail me directly for a private copy.
> > //Dan
> > On Sunday 03 December 2006 05:13, Graham Haddock wrote:
> > > Kees:
> > >
> > > 1.) A breakdown voltage appropriate for the voltage/power levels you
> > > will be switching.
> > > 2.) A low series on resistance appropriate to minimize losses at the
> > > impedance/power you are handling.
> > > 3.) A low series off capacitance to minimize signal leakage when
> > > biased off.
> > >
> > > You didn't say whether you were doing high power transmitter output
> > > switching or low level receiver or transmitter switching.
> > >
> > > --- Graham / KE9H
> > >
> > > ==
> > >
> > > Kees wrote:
> > > > Can someone provide information on the best PIN diodes for HF
> > operation
> > > > if we want to use them for electrical bandswitching. What
> > > > characteristics do you look for ? Low capacitance, low inductance,
> > etc ?
> > > > 73 Kees K5BCQ
> > --
> > Dan Andersson, M0DFI
> > dan@... <mailto:dan%40andersson.co.uk>
> > dan.andersson@... <mailto:dan.andersson%40ieee.org>
Dan Andersson, M0DFI
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