IF you have two separate bias pots, I guess you could hook up an input signal and tweak both pots for the highest detected signal on the output. An AC voltmeter would help with that. There is probably a PC program (audio spectrum analyzer program?) that could take AC audio into the mike input and measure it for you if you do not have an AC voltmeter. - Dan, N7VE -----Original Message----- From: minima-bounce@xxxxxxxxxxxxx [mailto:minima-bounce@xxxxxxxxxxxxx] On Behalf Of ext Tayloe, Dan (NSN - US/Tempe) Sent: Friday, February 28, 2014 2:20 PM To: minima@xxxxxxxxxxxxx Subject: [minima] Re: KISS Mixer Musings You could bias the two JFETs with separate pots and adjust for similar drain waveforms. I think you would want to adjust for highest pk-pk on each drain. A lower voltage on one drain may mean that device did not turn fully off. - Dan -----Original Message----- From: minima-bounce@xxxxxxxxxxxxx [mailto:minima-bounce@xxxxxxxxxxxxx] On Behalf Of ext Joe Street Sent: Friday, February 28, 2014 1:56 PM To: minima@xxxxxxxxxxxxx Subject: [minima] Re: KISS Mixer Musings Just thinking about this. I remember that the transconductance of JFETS varies quite a bit so the fact that the signals are not symetrical might be due to an imbalance in the device characteristics? On 28/02/2014 3:29 PM, Mark G0MGX wrote: > Hi Joe > > The 'scope was connected to the drains using a x10 probe - they were > still connected to the transformers in circuit. The overall output at > the IF port didn't change with the 'scope connected as the SA was > monitoring throughout. > > Mark > > > On 28/02/2014 19:24, Joe Street wrote: >> When looking at the drain voltages with the scope did you give a load >> resistance to the drains or was it just the scope input? >> >> On 28/02/2014 1:41 PM, Mark G0MGX wrote: >>> Hi Team >>> >>> I've been threatening to have a fiddle with the KISS mixer for a >>> while, and here are the results of my first bash: >>> >>> http://g0mgx.blogspot.co.uk/2014/02/kiss-mixer-musings.html >>> >>> I don't understand the 'scope signals on the drains of my FETs and I >>> certainly don't understand the voltages I am reading on the sources >>> (my sources are together and connected to the bias supply). The >>> power end of the 4K7 to the FET bias adjusts from 0 to 5V as >>> expected by I am reading -ve voltage on the sources themselves. >>> >>> Please take a look at the link and then any volunteers who can try >>> and explain this to me most welcome! >>> >>> Mark >>> G0MGX >>> >> > >