The Farhan Minima RF Mixer

I have been wanting a simple Mixer Circuit for experiments in my electronics shop, and most recently for use with my Small Signal Amplifier (see previous post).

Alan - K6ZY at the last Puget Sound QRP (pQRP) meeting mentioned he was considering building a Homebrew Farhan VU2ESE Minima Transceiver project.  After looking at the schematic for the Mimina, it appears that the Mixer Circuit would work very nicely as an stand-alone mixer for my experimental use. Very good documentation of the mixer's operation is provided by Farhan. The mixer used in the Minima has been dubbed the “KISS Mixer” by Chris Trask in his paper.

Minima Mixer Circuit in LTSpice
(See file below)

To play with the idea of building an experimental mixer, I created a LTSpice simulation circuit to start my understanding of it operation.

So far I have not gleamed much information from the LTSpice simulation, but maybe I have something wrong with my circuit; bias, configuration, signal levels or expected output. Or, maybe LTSpice can not deal with mixed signals correctly, but  I will continue working with LTSpice to learn more.

In preparation for my experiment and use of the Mixer Circuit, I have started the initial design of a PCB using DipTrace. Keeping with my ever present Goal of building electronic projects as small as I can, this initial design is larger than I think the final design will be, as I have currently configured it to used larger components than necessary. I think I can find small SOT-23 J310 JFET packages and smaller transformer cores. But this is a start.

Mixer Layout in DipTrace

 I have configured the PCB as a single-sided circuit as it can be produced with simple Homebrew Toner Transfer Method. But perhaps, using double-sided will be best for reducing the over all size.

This mixer as a stand-alone device will be very useful in my electronics shop - Thanks Farhan.

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UPDATE: Aug 7, 2014 07:46

Here is my "SpiceMixer01.asc" file that I have been playing with.

Version 4
SHEET 1 880 680
WIRE -224 -352 -704 -352
WIRE -160 -352 -224 -352
WIRE 144 -352 -80 -352
WIRE 256 -352 224 -352
WIRE 256 -336 256 -352
WIRE -224 -320 -224 -352
WIRE -704 -288 -704 -352
WIRE 304 -288 224 -288
WIRE 144 -272 144 -288
WIRE 256 -272 144 -272
WIRE -224 -224 -224 -240
WIRE 144 -224 48 -224
WIRE 256 -224 256 -272
WIRE 256 -224 224 -224
WIRE 464 -224 256 -224
WIRE 544 -224 528 -224
WIRE -704 -192 -704 -208
WIRE -576 -192 -704 -192
WIRE 48 -192 48 -224
WIRE 304 -192 304 -288
WIRE -704 -160 -704 -192
WIRE -224 -144 -352 -144
WIRE -352 -128 -352 -144
WIRE 0 -128 -32 -128
WIRE 400 -128 352 -128
WIRE 544 -128 544 -224
WIRE 608 -128 544 -128
WIRE 544 -96 544 -128
WIRE -352 -80 -352 -128
WIRE -224 -32 -224 -64
WIRE -144 -32 -224 -32
WIRE 48 -32 48 -96
WIRE 48 -32 -64 -32
WIRE 176 -32 48 -32
WIRE 304 -32 304 -96
WIRE 304 -32 176 -32
WIRE -224 0 -224 -32
WIRE -352 32 -352 0
WIRE 544 32 544 -16
WIRE 400 128 400 -128
WIRE 400 128 224 128
WIRE 144 144 144 128
WIRE 256 144 144 144
WIRE -32 192 -32 -128
WIRE 144 192 -32 192
WIRE 256 192 256 144
WIRE 256 192 224 192
WIRE 320 224 320 192
WIRE -224 256 -720 256
WIRE -176 256 -224 256
WIRE 144 256 -96 256
WIRE -224 288 -224 256
WIRE 224 304 224 256
WIRE -720 320 -720 256
WIRE -224 400 -224 368
WIRE -720 432 -720 400
WIRE -560 432 -720 432
WIRE -720 448 -720 432
FLAG 176 32 0
FLAG 224 304 0
FLAG -352 32 0
FLAG 256 -336 0
FLAG -224 -224 0
FLAG -224 400 0
FLAG -352 -128 Bias
FLAG -224 -352 SigIn
FLAG -224 256 LO
FLAG 608 -128 SigOut
FLAG 544 32 0
FLAG -704 -80 0
FLAG -720 528 0
FLAG -576 -192 SampleSig
FLAG -560 432 SampleLo
FLAG -224 80 0
FLAG 320 224 0
SYMBOL ind2 128 144 R270
WINDOW 0 40 34 VTop 2
WINDOW 3 65 78 VBottom 2
SYMATTR InstName L1
SYMATTR Value {Lo}
SYMATTR Type ind
SYMBOL ind2 128 208 R270
WINDOW 0 34 32 VTop 2
WINDOW 3 60 86 VBottom 2
SYMATTR InstName L2
SYMATTR Value {Lo}
SYMATTR Type ind
SYMBOL ind2 128 272 R270
WINDOW 0 35 38 VTop 2
WINDOW 3 63 77 VBottom 2
SYMATTR InstName L3
SYMATTR Value {Lo}
SYMATTR Type ind
SYMBOL ind2 128 -336 R270
WINDOW 0 38 38 VTop 2
WINDOW 3 63 78 VBottom 2
SYMATTR InstName L4
SYMATTR Value {Ls}
SYMATTR Type ind
SYMBOL ind2 128 -272 R270
WINDOW 0 34 29 VTop 2
WINDOW 3 60 76 VBottom 2
SYMATTR InstName L5
SYMATTR Value {Ls}
SYMATTR Type ind
SYMBOL ind2 128 -208 R270
WINDOW 0 32 38 VTop 2
WINDOW 3 61 80 VBottom 2
SYMATTR InstName L6
SYMATTR Value {Ls}
SYMATTR Type ind
SYMBOL njf 0 -192 R0
SYMATTR InstName J1
SYMBOL njf 352 -192 M0
SYMATTR InstName J2
SYMBOL cap 160 -32 R0
SYMATTR InstName C1
SYMATTR Value .1uF
SYMBOL voltage -352 -96 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 5V
SYMBOL voltage -224 -336 R0
WINDOW 3 24 44 Left 2
WINDOW 123 24 72 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 10uV 7Meg)
SYMATTR Value2 AC 1mV
SYMATTR InstName V2
SYMBOL voltage -224 272 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value PULSE(0 70mV 0 0 0 {PulseWidth} {Period})
SYMBOL res -176 -336 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 -5 56 VBottom 2
SYMATTR InstName R1
SYMATTR Value 50
SYMBOL res -192 272 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 -5 56 VBottom 2
SYMATTR InstName R2
SYMATTR Value 50
SYMBOL res 528 -112 R0
SYMATTR InstName R3
SYMATTR Value 50
SYMBOL res -720 -304 R0
SYMATTR InstName R4
SYMATTR Value 100K
SYMBOL res -720 -176 R0
SYMATTR InstName R5
SYMATTR Value 1K
SYMBOL res -736 304 R0
SYMATTR InstName R6
SYMATTR Value 10Meg
SYMBOL res -736 432 R0
SYMATTR InstName R7
SYMATTR Value 1K
SYMBOL res -160 -16 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R8
SYMATTR Value 4.7K
SYMBOL res -240 -16 R0
SYMATTR InstName R9
SYMATTR Value 8K
SYMBOL res -240 -160 R0
SYMATTR InstName R10
SYMATTR Value 2K
SYMBOL cap 464 -208 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C2
SYMATTR Value 10n
TEXT -512 -280 Left 2 !.tran 0 10uS 9uS
TEXT 392 -416 Left 2 !.param Ls = 10000nH\n.param Lo = 10000nH\nKo L1 L2 L3 1\nKs L4 L5 L6 1
TEXT -800 -408 Left 6 ;WA0UWH
TEXT -272 448 Left 2 !.param Freq = 27Meg\n.param Period =  1 / Freq\n.param PulseWidth = Period / 2 * 1.05

-- Home Page: https://WA0UWH.blogspot.com

December 2009 - pQRP P&C

Last night I went to our monthly Puget Sound QRP (pQRP) P&C (pie and coffee) meeting.

For the event the group decided to do a White Elephant Gift Exchange, supposedly giving something from our junk box. I checked my junk boxes for an appropriate gift to take - it was something that I would have liked to have received, and wraped it for the exchange.

At the meeting and after dinner, I was one of the last to pick a gift from the gift pile, I selected a small package and was surprised. It was a Soft Rock 40 Kit (a receiver) - Very nice gift from someone that has an very impressive junk box. But, sad to say, in keeping with the rules of the White Elephant Gift Exchange, my Soft Rock Kit was taken by Alan K6ZY (the next in line to pick a gift), Dang!  ;-(

OK, as per the rules, I had to pick another gift, again I picked a small gift and to my surprise, it was a TAK-40 Kit  (a Transceiver, parts and boards). Again, some of the guys at the meeting must have very impressive junk boxes.  Yet, not knowing exactly what a "TAK-40" was, after the meeting and at home, I spent several hours on the web reading and learning all that I could about it.  Sometime early the next morning I got to sleep.

Well, I am thankful to who ever provided the Gift, I will put it to very good use, I may even spend some time increasing my code speed  - Thanks.


UPDATE 1:

• After reading much more on the web, The TAK-40 looks like it is going to be a bit of a project, to find; construction details, modification details, and all sorts of information to ingest and digest.

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November 2009 - eBuild-A-Thon and BBQ

WOW, the November 2009 - eBuild-A-Thon and BBQ has come and gone, we had several projects being worked in different parts of the Shop at the same time -  I could not keep up with all of the very interesting projects, activities and chats. Sorry, photos were not taken.

The QRSS "Beac-in" (not talk-in) beacon was not found, no one brought DF equipment - therefore the prize will be saved for the next event in December.

By my count, there were 22 people that came by to work on projects or just chat throughout the day. Unfortunately, I did not get a complete list of names and calls, forgive me if I don't mention your name or project. Next time I will try to have a official "meet and greeter", to help with names, notes and project photos.

Roger K7RXV brought his network analyser, but I think he worked mostly on a PCB case for an Intermod Meter.

John KC7NVE brought his Transceiver, Portable Antenna and Laptop, to demonstrate station operations in; SSB, CW, and WSPR modes.

Doug W7RDP brought his Lineman Crimping tool for demonstration and use, Doug brought  a section of very small (1/8 inch) hard-line. It will be used for future project intra case connections.

Lyle KK7P worked on a PCB case for one of his  projects, by the count of the accumulated  punched circles at the base of the punch he was a very busy person. I am looking forward to see the resulting case and finished project.

The Next Day Photo

I love the evidence of intent work

Thanks to Lyle, we will now have many large "manhattan style" PCB construction components.

Alan K6ZY worked on repair of a watt meter via meter replacement and face plate adaptor.

For a while, there was competition for the punch access with so many PCB projects needing holes punched. Die changes were coordinated for best overall effective use.

Thanks to my sister, Carolyn, Lunch was served adhoc and projects were continued though out the day.

Tess (my dog) thought it was great - she had so many people that were willing played ball with her - she was exhausted by the end of the day, but she loved every minute.

Thanks to all for a enjoyable event.

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E-Mails

I had a great time at Eldon's eBuild-a-Thon today.

Eldon, your shop facility is, like, awesome, dude. Totally.

And the hospitality was superb. Thank you, than a big thanks to Carolyn
as well.

I'm hooked!

73,

Lyle KK7P

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All,

Just wanted to mention Richard L's Thames & Komos Radio Ace medium and shortwave dual-triode regenerative receiver he took to a past Build-A-Thon does work. It seemed to not work at the past Build-A-Thon because it has much poorer sensitivity than we expect from regenerative receivers. But today Richard turned it on in the low lands of Snohomiosh county and received multiple BCB (AM broadcast band) stations. Selectivity seems good for a simple receiver.

I'm hypothesizing using B+ = 12 volts on a 12AU7 handicaps the tube. (Or is it a 12AT7 or 12AX7?) Unlike most one or two active device receivers I've played with, an adjustable antenna loading coil did not improve volume on the AM BCB.

Annie, Richard, and I very much regret missing the Build-A-Thon. Richard is in pain from extensive (3-hours) dental work yesterday. I've not fully recovered my strength from mild food poisoning on Thursday. After describing a past Build-A-Thon to some e-pen-pals, some (hams in Kentucky, and Japan, and a technical university professor in Lima, Peru) have emailed me with very positive comments.

Very best regards and wishes to all,

Steven, KD7YTE

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