That's in line with my readings too. But the oscillator is 3v peak to peak! That makes it quite strong compared to the tx signal. - f Sent from BlackBerry® on Airtel -----Original Message----- From: Mark G0MGX <mark.g0mgx@xxxxxxxxx> Sender: minima-bounce@xxxxxxxxxxxxx Date: Sun, 19 Jan 2014 16:24:07 To: <minima@xxxxxxxxxxxxx> Reply-To: minima@xxxxxxxxxxxxx Subject: [minima] Re: Mixers and Crystal Filters Marker 2 is the LO direct to the SA, marker 1 is post mixer. I make LO suppression through mixer is 33.4 - 8.4 = 25dB Mark G0MGX On 19/01/2014 16:00, farhanbox@xxxxxxxxx wrote: > Mark, you probably swapped the z and 14 mhz values in the last sweep. > Can you tell me how much local oscillator suppression are you getting? > I don't know what you ref levels are. > - f > Sent from BlackBerry® on Airtel > ------------------------------------------------------------------------ > *From: * Mark G0MGX <mark.g0mgx@xxxxxxxxx> > *Sender: * minima-bounce@xxxxxxxxxxxxx > *Date: *Sun, 19 Jan 2014 15:15:30 +0000 > *To: *<minima@xxxxxxxxxxxxx> > *ReplyTo: * minima@xxxxxxxxxxxxx > *Subject: *[minima] Re: Mixers and Crystal Filters > > All, > > I've added another example with a 7MHz signal to the RF port and 27MHz > to the LO port and updated this page appropriately: > > http://g0mgx.blogspot.co.uk/2014/01/yet-more-minima.html > > I also experimented with the 15MHz low pass filter and made another > using T50-6s (13 turns for 0.66u and 14 turns for 0.78u) and the sweep > looks almost identical to the previous one using T50-2s so I will have > to come back to that filter again as I suspect I have too much > attenuation at 14MHz. We will see! > > I have just made the BFO and uploaded some info here: > > http://g0mgx.blogspot.co.uk/2014/01/minima-bfo.html > > Mark > G0MGX > > > On 19/01/2014 08:23, Ashhar Farhan wrote: >> mark, >> the local oscillator has to be at 27 mhz. on the higher side. this >> will reduce the local oscillator leakage to the RF port (you can see >> that the oscillator suppression isn't any great shakes. It is about >> -40dbm. That will be only 20 db below the tx signal level unless the >> LPF kicks in. >> - f >> >> >> >> On Sun, Jan 19, 2014 at 1:02 PM, Mark G0MGX <mark.g0mgx@xxxxxxxxx >> <mailto:mark.g0mgx@xxxxxxxxx>> wrote: >> >> Hi Team >> >> Some more musings of mine on the mixer output, crystal matching >> and selection plus a sweep of my crystal filter... >> >> http://g0mgx.blogspot.co.uk/2014/01/yet-more-minima.html >> >> Mark >> G0MGX >> >> >