EMRFD Message Archive 7241
Message Date From Subject 7241 2012-02-12 21:54:08 Ashhar Farhan the kiss mixer, some more questions
i am trying to build the kiss mixer with discrete devices. i want to
understand a few more things...
1. as a switching mixer, i suppose the same considerations apply as a
diode mixer? in particular, we have to keep the IF port terminated at
50 ohms. so, will a regular bandpass/bandstop kind of a diplexer do
the trick?
2. is there a reason why this will not work in an up-converting scheme?
3. 2N7000 has a 10nsec switching time, not really suitable for VHF
work. how about using regular FETs like J310?
my very modest home lab tops out at 40 MHz, hence my questions without
trying it out.
- farhan7243 2012-02-13 06:10:21 Chris Trask Re: the kiss mixer, some more questions
> i am trying to build the kiss mixer with discrete devices.
> i want to understand a few more things...
>
> 1. as a switching mixer, i suppose the same considerations
> apply as a diode mixer? in particular, we have to keep the
> IF port terminated at 50 ohms. so, will a regular
> bandpass/bandstop kind of a diplexer do the trick?
>
http://www.home.earthlink.net/~christrask/Paper022.html
>It will work equally well for up-conversion.
> 2. is there a reason why this will not work in an
> up-converting scheme?
>
>JFETs won't provide the low drain-to-source resistance (Rds) that mixers require for low conversion loss and low IMD performance. I have not seen any discrete MOSFETs that will work will in the VHF range. Perhaps others on this list would know of suitable devices.
> 3. 2N7000 has a 10nsec switching time, not really suitable
> for VHF work. how about using regular FETs like J310?
>
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/7249 2012-02-13 21:43:02 cbayona Re: the kiss mixer, some more questions
work, they have extremely fast speed.
At 08:10 AM 2/13/2012, you wrote:
> >--
> > i am trying to build the kiss mixer with discrete devices.
> > i want to understand a few more things...
> >
> > 1. as a switching mixer, i suppose the same considerations
> > apply as a diode mixer? in particular, we have to keep the
> > IF port terminated at 50 ohms. so, will a regular
> > bandpass/bandstop kind of a diplexer do the trick?
> >
>
> Yes, and you might want to consider my approach to mixer diplexers:
>
> http://www.home.earthlink.net/~christrask/Paper022.html
>
> >
> > 2. is there a reason why this will not work in an
> > up-converting scheme?
> >
>
> It will work equally well for up-conversion.
>
> >
> > 3. 2N7000 has a 10nsec switching time, not really suitable
> > for VHF work. how about using regular FETs like J310?
> >
>
> JFETs won't provide the low drain-to-source resistance (Rds)
> that mixers require for low conversion loss and low IMD
> performance. I have not seen any discrete MOSFETs that will work
> will in the VHF range. Perhaps others on this list would know of
> suitable devices.
>
>
>Chris Trask
>N7ZWY / WDX3HLB
>Senior Member IEEE
>http://www.home.earthlink.net/~christrask/
Cecil
k5nwa7250 2012-02-14 04:57:04 Chris Trask Re: the kiss mixer, some more questions
> I've wondered if Bipolar transistors operated in Avalanche
> mode would work, they have extremely fast speed.
>
Chris