42 - Mixers & Modulators 

Nick, you may not be "an expert" but you're utterly brilliant! And your joy really makes these videos priceless. Thank you so much. I'm learning a ton.

Dear Nick, you are a natural-born teacher. TNX for the video! I love how you explain something complicated in such a practical simple way. Have learned a lot from this video and will wacht them all! The downside for me is that I now realize that my homebrew stuff isn't as good as I thought. Keep it up Nick.

I have not got to the end of this video yet but from what I have just seen, this is one of the best instructional videos detailing how to implement mixers and especially modulators. Great work!

Brilliant mate! Great step-by-step of your findings.

Wow, what a difference the matching made! Being able to show the various stage results on the spectrum analyser is a great help to viewers and learners. It's great to see how these elements of design fit together to give the desired result. There are so many vicar jokes, they must be almost an occupational hazard. 🤣 Thanks for making this video and have a great holiday.😆👍

Impressive work with new insights for me. Thanks a lot for it. Can't wait to see the next video on this topic.

Nick, this video is pure gold! I watch so many similar channels that you probably also watch, but your comparison of the different improvement steps you went through is second to none. Have a great holiday and looking forward to the next videos. 73 de Cedric ON4CKM

The Si5351 is made to drive Cmos loads. The termination of mixer and generator is important as during the cycle they would be momentarily in no-man's land. An attenuator is a good idea, and using a diplexer is a great idea. Great improvement. Makes filtering of Carrier much easier with a less than ideal filter.

This was a very useful video, thanks for making it. The impedance matching on the LO at the end was neat to see. I am looking forward to schematics in the next one -- I'd like to see how you applied the diplexer on that port.

Yes, I think you've got something here. I'll have to look at the uBITX V.6 schematic I have on my wall to see what Ashhar did.. I do know he used the BAT54S Diode Array Schottky which is basically two schottky's in a single package surface mount, and used two for a ring. I'd also like to know what the 7300 does as I can hear carrier and I don't think mine is balance well. I'm also looking into replacing the diode system in a very old radio, a swan ss-200 to see what I can do with it. That said, the original had a way of balancing it so maybe I should leave it alone.

Been trying to get back into home brewing but this time with test-equipment that I lacked before so will be keen to replicate some of your experiments. I hope that you will show your design methodology for both the diplexer and the impedance matching (which I assume is some kind of L-network). It was often said by Doug DeMaw that you could build superior equipment using simple designs by paying strict attention to detail; your demonstration really brought that home in that you attained superior performance to the commercial mixer which is so coveted by homebrewer hams these days; I remember stripping a few of these out of satellite receivers myself. Long ago, when I would visit hams that built their own equipment, I was often taken by how incredible the fidelity of their audio, both clear and full-range. Another time when a ham remarked how the Drake audio had a great natural sound, another ham remarked that if you look at the Drake circuitry, on the surface there isn't anything all that earth-shaking but they did pay extreme attention to details among them careful interstage impedance matching that mostly goes unnoticed. Just ran across your channel and subscribed; will also look at you other videos including the mixer ones mentioned. Thanks for putting these out! 73...

Really nice video, explained very well. Waiting for the diode matching video. If I can make a suggestion, investigate on matching the best you can all the ports, digging very deeply in it. You have already noticed that it matters really heavily. Thank you very much. 73 de IZ4HDM Cristiano

Really good. Many thanks. 73 Ellis GM4GZW

looking forward to the schematics next time, Mike, EI6AU

That plane vanilla mixer is used in the VEGA Selina.

I was hoping you were going to slap a 120 ohm resistor across the output of the SI5351 to see if the improved match did the job even though the waveform was still square.

As for the LO impedance match, you could use a simple emitter follower and suitable emitter resistor.

Hi Nick, I can’t find any information on the internet regarding the audio diplexer. the schematic can be traced from the video, but the values can't. If you could reveal the values of the components, I can finish this part. Thank you in advance.

Hi Nick, You talked about a diplexer for the LO, did you actually build that? Is the bandwidth of the diplexer sufficient for the wide range of the LO. A band pass filter can be designed with 85 ohm input and 50 ohm output, wouldn’t that do the trick as well?

I can hardy wait. I have a few thousand surplus FH1100 mixing diodes just waiting for projects. I'd love to see how you match them so I can do the same.

I am intrigued by the wiggly traces on Andy's board, I'm guessing some impact at VHF UHF. Can anyone enlighten please? Thanks.

Hi Nick, ... what does it mean, when you are telling: "...dickings of a job, ..." (timestamp:17:00 ) I'm not a native English spoken person, would you please help me? Sometimes you 'surprised' me, a lot, ... ! You have to know, ... also the 'translation' has no glue, what it means, ... and me too. Be so kind, and help the 'knowless' people around you, ... I 'm impressed, that the results are so good and waiting for the next videos, ...! 73 de Markus - db9pz (JN39fq 3miles/5km, east of LX)

If you don't match the L-R-I impedance's on a commercial diode ring mixer performance will hands down suffer. They are good at what they do, but they are finicky that way.