We will need two of these for the bandpass filter board in our Direct Conversion receiver. This 10 minute video shows you how to wind these transformers.
@@soldersmoke Yeah, it's not so much keeping track of which wire is which but when the phasing dots are included because they're important I always have to reinvent the wheel! 😂
For use with the diode ring: ID wires 1, 2 and 3. Designate wire one as the RF or LO input. Top to input, bottom to ground. The, Top of two to bottom of 3 -- solder these together. They will either go to ground or to AF out. The two remaining wires go to the diode ring (top and bottom or left and right). Hope this helps. It is hard. We chickened out with the students and made use of trifilar toroids wound in Hyderabad! 73 Bill
Very interesting. I was wondering if you would check the inductance, and you did. Something I've been trying to find out is, what would you expect the inductance to be with a double balanced mixer? If you just measured one of the trifuler windings on the toroid? I have a cheap L/C meter on the way, which according to the specs can read quite low inductance. I plan to do some experimentation. For instance. Could I make a diode ring mixer using air wound coils? Could I use the little toroids I've savaged from old light bulbs? I've only just started out with diode ring mixers, but when my inductance meter arrives, these are the things I plan to experiment with.
Trevor: A while back Farhan gave me a box of trifilar toroids made of the usual -43 material. I measured the turns at 33uH each. These are the transformers we are using in our DC receivers. I have also used them in the diode ring mixers of several homebrew rigs -- they always work for me. Yes, air core would also work -- in the original version of the BITX 20 Farhan was using nylon washers as the toroidal cores. And I think he was using 3D printed plastic cores in his Daylight Again rig. I think toroidal cores are best because they are self-shielding, and realize that the ferrite or iron powder cores let you get to a given inductance with far fewer turns, and thus with probably higher Q. 73 Bill
Bill. Just a bit more on my double balanced mixer adventures. I was in contact with Pete Juliano a month ago. I had thanked him for his 3 part series on double balanced diode ring mixers. He warned me it was not to taken lightly. That unless I was extremely lucky, I would not get the same results as a commercialy made unit. He wasn't trying to put me off, and didn't. He named some of the ones you could get, and how they were cheaper now. I think I might buy an ADE-1 to use in what I'm building. I can then use that as a guide to how well my home build ones are performing. My interest in DBM all started when I decided I wanted to build an upconverter for my cheap SDR dongle.
Trevor: This is one of the topics on which Pete and I disagree. I think you can make your own diode ring mixers using transformers you wind yourself. You can see the results in the many DC receivers currently being built. Sure, you could buy an SBL-1 or an ADE-1 (and I have used both). But by the same token you could buy an ICOM 7300, right? in the high school DC receiver project we wanted to keep it as homebrew as possible. That is why we are using an LC analog VFO (not an Si5351) and homebrew BP filters and homebrew diode ring mixers. Different strokes for different folks. To each his own. This is all for fun. 73 Bill
Thanks Bill. Point well taken. The ADE-1 can wait for another day. I know pleasure of building something yourself and have it work. I've spent quite a bit time accumulating knowledge, the theory, the last few weeks. It's time to do more actual building.
Man, that video was REALLY helpful! Very clear and concise! Just what I was looking for to be sure I properly wind that transformer. The mixer transformers seem much more complex. I am having difficulty understanding how to do the "trifiller" thing and getting the windings correctly oriented..... Would love to see a similar video demonstrating how to wind that one properly! Great stuff Bill! 73 Pete KD2OMV
Thanks Pete. I will try to make a video about how to build a trifilar transformer. But in the meantime the internet could help. You really just take three insulated wires, wrap them together, then wind them through the toroid as if the bundle were a single wire. You end up with three at the top and three at the bottom of the toroid. You usually use one (say #1) wire as the input link (one of these wires to ground, the other taking the input). You take the bottom of #2 and solder it to the top of #3. This is often the ground point, with the other ends going to the diodes in a mixer. It is not that bad. You just have to think a bit about what you are doing and how that relates to the schematic in front of you. Doug DeMaw had a lot of good diagrams on this -- I am pretty sure you can find them on the internet. Hope this helps. 73 Bill
@@soldersmoke Thanks so much for the kind reply, Bill....that makes complete sense; twist three together THEN wind them, therefore, not having to worry about winding one coil in the opposite direction by mistake....I believe you shared a story in one of your wayback podcasts about having had some such trouble winding a coil in the wrong direction, and figuring it out years later when you finally got the rig working???? (Tuna Tin or some such rig??) That was all I was thinking about when I stared at the schematic and those phasing dots....LOL!...meanwhile, I managed to find this RU-vid video on the subject, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DVqqOT1ONsY.html, and I assume what this guy is doing is what is needed for your mixer?? Hopefully that will help others looking for a walk through on building the transformer.... Can't wait to get this receiver going....It will hopefully be a good match to the 6T9 single tube transmitter I built a while back. I am still proud that my call sign is written on your "ET2"...is it still hanging on the wall? 73 Pete KD2OMV
