Solid State Shortwave RF Preselector

[@marksmeaton1470]

Excellent tutorial. Im fifteen years old again, at the kitchen table fooling around with crystal sets and amplifiers. Brilliant!

[@MIKROWAVE1]

I loved those old 1970s experimenters project books and mags.

[@alexwild4350]

Thank you for taking the time to put this video together. I still have the books that described such circuits from the time I was a young lad way back in the 1970's where I would avidly read, wonder and imagine far more than I understood about what these circuits could do. That imagination has remained with me unchallenged, unrealised in the real world for the next 50 years. Your half hour video on the subject is but a blip in the big scheme of things [and could have been longer - I'd have still watched] and everso appreciated that you've taken the time to describe and build and all I had to do was turn up and watch. Thanks so much.

[@biju209]

I am a professional engineer but still I get to learn so much from your videos. You experiment some topics which no text book does. Thank you very much for these excellent videos.

[@W1RMD]

I really appreciate the job at 4:17! I'd have to improve my skills a bit to build something like that that works with my slobbering iron.Great video! I don't mind a bit that you "went over". You crammed years worth of knowledge in under 45 minutes and even gave us the schematics. Thank and 73's!

[@karlschulte9231]

Great fun. I have built several Doerle duplex type regens ( 6sn7 dual triode ver) and have been lucky in that i grabbed velvet vernier dials and that ilk when young. Saved tube type resistors and plug in coils/ sockets too. Just now am working on several transistor/ opamp modern sets and restoring my Dad's 1950 xtal set. ( W5EWF, sk). It even has an S meter! Pancake 2 stage tuner, tapped rf and adio coils for precise match. Amazingly sensitive. These sets still amaze me. You always peesent excellent videos! Thanks. 73 Karl, WA2KBZ

[@tennesseered586]

Great stuff here. I especially like how you evaluate each circuit option, consider all the variables, and come to a balanced decision on which you prefer.

[@MIKROWAVE1]

As they say - there are many ways to get to Chicago...

[@acestudioscouk-Ace-G0ACE]

I know this took a lot of time and work but I am so grateful for it. I'm a returning ham after a 30 year break. I have no electronics background and have a 68-year-old brain and so don't learn as easily as in my youth. Your teaching style is easy to follow and I'm getting there! Going to have to look into what you mean by "bias" in this context as I'm not clear on that just yet. Thanks again.

[@conservative599]

Hi, I am also 68, but have been working in Electronics since 4th grade, I found one of my business cards for Transistor & Tube Radio Repair growing up in rural NJ. I had a mentor, WW2 Vet who ran a a TV repair shop in Newton, and my Mom would drop me off there while shopping. I had some red cover book on Transistor Radio Servicing, and remember asking Mr. Decker what BIAS was all about!!! Basically it is just like IDLING in your car or lawn mower. The Idle screw sets the no-load engine speed. Similarly, Bias is as simple as 1 or better 2 resistors from the main voltage supply as a voltage divider, to drive the Gate, Base, or Grid input of your active device. For BIPOLAR Transistors, it is often 0.7V Silicon or 0.2V for Germanium. For FETS it can be 0V for Depletion mode, where the rated 10-50mA IDss Drain Current operating point results. For tubes it usually starts NEGATIVE with respect to the cathode, cutting down the Plate current or gain. The wanted signal is overlaid onto this DV set point, thru a DC blocking capacitor, and swings above and below the bias point. Hope this helps explain the basics, W4HDL in USA...

[@acestudioscouk-Ace-G0ACE]

@@conservative599 Hi and thanks very much for taking the time to explain this. The car idling metaphor was good for me as I've set up quite a few car engines in my time. Talking of time, it's moved on. When I wrote it must have been just before my birthday as I am now just turned 70! Thanks again, I appreciate it.

[@maxxsmaxx1901]

I have been a great fan of RF since my school days. I can swear that no one else explained and demonstrated the subject better than you. Thank you . Thank you ! God bless .

[@wa9kzy326]

Very ell presented. You might be interested in this bit of related nostalgia. Back in '72, one of the popular electronics magazines ran an article about printed inductors. I ordered the PCB and it had 2 "coils" etched into the copper with space for 2 JFETs. It was an RF preamp for the FM broadcast band; each stage had a variable cap to peak it. Wow! That thing was red-hot, which I needed, living in the deep boonies. Thanks again for sharing your views on electronics.

[@stevenlitkey9354]

GOOD GOOD GOOD stuff as always !! Love your vids on crystal sets. Started playing with crystal radios again about a year ago, and they are a ton of fun !! Not a radio or electronics guy by any means, so my radio experimenting is truly hit and miss, but that in itself adds to the fun and enjoyment.

[@fourfortyroadrunner6701]

In 65 I got my novice (I'm 75) and had some REALLY low end receivers. S-38 Hallicrafters, Heathkit AR-3, later fed by an ARC-5 used as an 80M to broacast band converter, and finally, an RME 4350A, which I STILL HAVE. At some point I acquired an RME DB-20 preselector, and that was a valued item for many years. The mice got into it and I believe I finally threw it out years back

[@MIKROWAVE1]

My first was this sears 5 transistor plastic radio that actually had plug in coils! I think it was an Elenco. My first with a BFO was a military surplus BC652 that covered the marine band and only 80M.

[@ssboot5663]

Love your stuff! Wish I had your knowledge and talents! It's something to be very proud of! Thanks for the videos!

[@coffeecuppepsi]

This was great. Ive tried for so long to build a receiver. So far no success, but this is the sort of tutorial i need

[@redhawk449]

New sub. Very interesting and informative video. I have printed Electric Radio magazine for the last 25 years and have just started to be interested in building my first a crystal radio.

[@fredfeldmeier8228]

Excellent American Radio Frequency Engineering.. keep up the good work Thanx..👈😎👍

[@MIKROWAVE1]

Thanks for watching Fred!

[@francoisdastardly4405]

Wonderful information. I really enjoy your video. Thanks !

[@teechui2401]

I use a Dremel with a small cutting wheel to make scores/gaps in the copper. In this way you can set up your power bus also by scoring a couple of parallel lines near one edge, using your thumb/fingers as a spacer as you run along the side edge. This makes an isolated strip maybe faster than attaching another piece. Also the Dremel cutter works well for making a 'plus sign' inside an island which makes a nice 4-pad setup for small surface mounts like BF998 DG MOSFETS.

[@MIKROWAVE1]

This is a great technique, with good eye protection, of course!

[@conservative599]

Great idea on the excellent 40673 replacement - how to mount it! I have been a ham since 1969, and have been hoarding all the great DG Mosfets and VFETS of the era to build stuff if I ever retire... I have an old 100KHz Calibrator PCB on my desk at work, carved out using an X-ACTO knife, to copy the circuit in a a college ham radio club/roommates Kenwood R-599', for my old tube National NCX-200, all I could afford! His Dad was a doctor and he had the money for the silver front Kenwood 599 Twins! I now have 2 Twins, thanks to EBAY. Thanks, W4HDL

[@W1RMD]

@@conservative599 I miss my twins! What great rigs they were (are)!

[@Rev22-21]

New to the channel and must say I am impressed. Looking forward to viewing all your work!

[@benthere8051]

With the new prototyping services, you could have several "combs" etched and stored in your parts bin for prototyping.

[@MIKROWAVE1]

Good point! Somebody could machine these.

[@benthere8051]

@@MIKROWAVE1 The PC board prototyping shops could make your "comb" using etched G-10 or FR-4. For circuits that are prone to external fields or circuits that radiate noise, I like to build boxes made of PC board material that can both contain noise and shield sensitive circuits from external fields. I came from the defense industry, where money was no object so we made enclosures of aluminum where we took a block of metal and machined away everything that didn't look like the enclosure we wanted to make.

[@hobbyrob313]

I want to thank you for this very interesting video! Thank you and best regards from the Netherlands (loc: Rotterdam) Rob.

[@984francis]

You are an excellent teacher.

[@chronobot2001]

Elevating the gate pad with an additional insulator will reduce its capacitance to ground. Also making the gate pad as small as possible will help.

[@marceloLoschiBH]

Fantastic!!!!!!!! Congratulations!

[@blacksmock445]

Very interesting video. It's just the type of experiment I like to do when I get time.

[@howardsix9708]

Used to make crystal sets in the 40's ...............still do................good upload.73, M0WEM.

[@lectrikdog]

Fascinating - I'd like to know if holes would work instead of slots on the faraday shield.

[@MIKROWAVE1]

Small holes are OK within reason for a Farady CAGE. But with a Faraday SHIELD, you are only trying to block the electric field and not the magnetic coupilng. So you need to make sure that the fingers or rods are grounded only at one end. They can be interdigitated. Alternating up and down from a grounded window frame - but the opposite ends must be open.

[@macgyver5108]

A Microwave oven is a pretty "basic" Faraday cage meant to stop the the microwave radiation waves which are blocked, even though the window in the door has "holes". The microwaves are the wrong "size" if you will to get through those holes. (That won't block an EMP like some think though, wrong frequency!)

[@markdonaldson5834]

Mike, Great video, I especially liked the explanation of how the Faraday shield works. Mark WA1QHQ

[@PapasDino]

Thanks for sharing Mike, good rundown! 73 - Dino KL0S

[@benthere8051]

Very well done, sir. I enjoyed your video. A transistor can be like a valve when it's an IGFET. Good idea on shorting the leads while soldering. I've been using that prototyping method very successfully. Amazon sells a diamond hole-saw set that works great for making islands for less than $8 that makes for attractive prototyping. The backside of your G-10 can be a power plane and the front side can be the ground plane. It is a really good low-noise construction technique. Also can a set of vertical wires soldered to the ground plane make a Faraday cage (I really like your idea). Question - I have often wondered about making a variable capacitor with a silvered glass tube and a high tolerance slug that is screwed in and out to make it variable. The dielectric constant of glass makes it possible to get good values of capacitance in a test-tube sized package. I also know the Russians make high-voltage variables out of glass. Has anyone tried this?

[@DAVIDGREGORYKERR]

Your favorite MC1350 can actually be used in an unbalanced configuration but with a center tapped coil on the output.

[@ingussilins6330]

Interesting E field screen between coils. :) Yes, 2N7000 bad for freqencies >1,6..1,8MHz (regenerative receiver stop's work). BS170 mosfet's work up to 30MHz in regenerative circuits.

[@Sergio-he8sw]

Very good explanation.

[@SpinStar1956]

Well thank you very much I greatly appreciate it. By the way this is one of my favorite channels on KZbin so keep up the great work and thanks again!

[@MIKROWAVE1]

ACD owns it now and the price keeps going up. I have upgraded twice. www.canvasgfx.com/en/products/canvas-x-2019/?gclid=CjwKCAjw98rpBRAuEiwALmo-ynn-EBxLGYRfflFCcJ186_3IdhlwCzE7fysr9nNz5vRLDwz1ElHkKBoCQEMQAvD_BwE

[@SpinStar1956]

Well after following your link and seeing the price I was going to make other comments but I will confine it to simply WOW!

[@microflite]

Great experiments! However, I think you can’t draw conclusions about bipolar vs. JFET vs. MOSFET without carefully tuning the input and output impedances at each stage. Also I the bipolar cascode, I’d suggest giving up a bit of gain on the first stage by removing the emitter resistor bypass - that’ll increase the input impedance of the first stage as seen by the tank and you can move the tap up and maybe you’ll get a higher overall gain. I watch all your videos!!

[@submarineradioman5535]

Nicely done!

[@donepearce]

In the times 1 (not ex one) mode, scope probes are already down on their response curve at 7MHz. Always try to use them in times 10 mode to preserve their bandwidth.

[@MIKROWAVE1]

My scope is not great! But good tip on using a 10K probe that is compensated.

[@KB4QAA]

This was a lot of work, but it is wonderful to compare performance of the circuits! 73 bill

[@kozkoz7776]

Those ugly construction are Beautiful really like this channel learning alot thanX

[@ON5ALE-Alessio]

Because going trough vacuum is encountering less impurities as going trough a layer of glassified sand

[@hayseed5467]

Great work as always, Mike. 73 de NØHUM, WBØDVM, NØTBH, KBØLMH . .

[@chronobot2001]

I'm thinking a piece of strip board would make a good Faraday shield if you shorted all the strips together and grounded them.

[@MIKROWAVE1]

Yes and just chop of the opposite end, removing the ground on top, thus forming the fingers.

[@michaelmacdonald3408]

Now you stick that board on what is its capacitance between main board and secondary that will have to be calculated into your sum.

[@acmefixer1]

The talk about using 18 volts for the cascode got me thinking about tube designs. When the plates need 100+V, and when the heater to cathode voltage is rated 100V max, it would be best to use a circuit that is cascode to the RF only, not the DC. One could do the same with the three 2N2222's too. The compliance would be better and the 9 volts would be more than adequate.

[@dm.2023]

Radio Shack in 2019? Must be the last one standing. I remember when Radio Shack made the switch to the Source around here. There was one Radio Shack in a nearby town that survived for about 4 years after the switch.

[@JohnnyClavin]

The Fetron was a range of solid-state, plug-compatible replacements for vacuum tubes (valves). en.wikipedia.org/wiki/Fetron

[@MIKROWAVE1]

I have a couple of ham friends who have solid stated some of the old monster receivers like the Superpro. It usually takes a hybrid approach between FETs and Bipolars to really do it.

[@СтаМилАлас]

Svaka čast majstore. 73 - Yu 1 qg

[@kennynvake4hve584]

a question...can you use copper tape, that is in a roll like duck tape...to make the circuits on, dead bug style. It would be a lot easier to put holes in...

[@MIKROWAVE1]

Well yeah! If you have some use it. Great for bottom of PC boards to add a ground plane too.

[@johnkolb1247]

Where is the video of the tube RF preselector? I would like to see details of the coil and shield.

[@MIKROWAVE1]

studio.kzbin.infos17y9wwMOPQ/edit

[@chrisharper2658]

I've used the NTE312 on a mini-whip antenna with reasonable success. I wonder how the NTE312 would compare to the MPF102? While the NTE is really a substitute brand, this was the only leaded part I was able to find that seemed suitable for the application.

[@krisraps]

How Do You Calibrate Such A Radio>? Where You Have The Bands Like That? I Don`t have A CLUE On How To Do So. How Do You Change The Widbandh On Them?

[@TheRogey1]

Hope your well in these tough times,really enjoy all your videos well presented. Have you played with the ZN414 TRF integrated circuit?,I have,worked well on broadcast band but with my tinkering I think I’ve blown it,no selectivity and only strong stations coming in.🤔🥴

[@MIKROWAVE1]

That was a great little device and quite a bit of gain in a small cheap package. I also remember the 703 IC, called the 99 cent wonder. The key to these bipolar devices was and still is, impedance matching so you do not load down the tuned circuit.

[@conservative599]

A great little 3 leaded??? part from FERANTI of the UK!!! I remember them from my Wireless World subscription growing up in the 70's. Never built anything with them however. BTW, Mike is my absolute, hands-down FAVORITE and MOST CREATIVE Ham Experimenter/Constructor/Instructor on KZbin!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Mike should have 100s X more views, and maybe some recognition from ARRL and add a PATREON account. I am adding to my "Ye Olde Junk Box" updating with the cool parts he is using, adding to my 1700SF Basement mostly filled with electronics from construction, consulting, and Ham Radio activities accumulated since the 1960's Thanks, W4HDL

[@СтаМилАлас]

Ovo sam pravio radi odlično. Bravo maestro.73 yu1qg milan.

[@DAVIDGREGORYKERR]

Would a MC1350 have worked better than desecrates, what about lifting the supply end of the 15K resistor to the first 2N2222 and connect that to the Emitter of the second 2N2222 to create a Ring Of Two amplifier and a ceramic capacitor between the emitter of the second transistor and ground.

[@glenngoodale1709]

Another great video

[@scharkalvin]

The problem with Manhattan construction is that the super glue used to attach the pads will generate eye burning outgassing when heated by the soldering iron. Use of a pad cutter drill might be a better idea.

[@MIKROWAVE1]

Ouch. And yes! So use a venting fan.

[@scharkalvin]

@@MIKROWAVE1 The heat also weakens the glue, I've had pads fall off after soldering. I've modified some small cap head screws with a dremel to serve as pad cutters.

[@MIKROWAVE1]

SHHH - yes

[@fournierfrancois2343]

Merci pour les explications...

[@SpinStar1956]

On another video of yours, I asked what schematic editor that you were using that you spoke about and said that you liked. I never did get a response to that question and would still like to know. I would like to use it for my students as I am a college instructor. I normally use our PCBoard software schematic editor but it really lacks a warm feel that the schematics and magazines like QST have. Please let me know, I would sure appreciate it.

[@MIKROWAVE1]

I do not use a schematic editor, I use an illustration program called Canvas, developed by Deneba Software and now supported by Corel.

[@Chris_Grossman]

I suspect a jfet feeding bjt cascode stage would be better than the 2 jfet input.

[@DAVIDGREGORYKERR]

If you want a tube what about the KORG NUTUBE 6P1 B+ 9-45V and a Heater voltage of 1.5V and might be usable in Push-Pull driving a center tapped output coil part of the tuned circuit for a TRF Radio, if you are using transistors what about a Ring of Three transistor amplifier.

[@MIKROWAVE1]

I saw that thing. Just what we need - another tuby acting device that has lots of "potential" for all kinds of circuits. Seems like a natural for sound effects pedals.

[@DAVIDGREGORYKERR]

@@MIKROWAVE1 You could use that in push-pull mode for preamplification in the preselector or as an AM modulator provided you connect a power transistor between the center tap on the heater and ground/negative so why not.

[@coffeecuppepsi]

23:14. How is the generator wired in? Just between gnd and the antenna? So its replacing the 50 ohm antenna. Also 5mV is huge... I thought a signal was in the uV range from an antenna... Any feedback appreciated, i been trying for YEARS to build a receiver

[@MIKROWAVE1]

Yes the signals we are handling are very small - some in the 10s of uV - but consider that 5 mV p-p is 1.76 mVRMS which into 50 Ohms is -36 dBm. That is a big signal towards the top of the range we might encounter, but it is not unrealistically large for a crystal set, or really any receiver. My equipment is crude, so I use big signals.

[@coffeecuppepsi]

@@MIKROWAVE1 this is very helpful to know, i kept adding multiple stages always assuming i needed to get from 10s uV to 100s mV. Additional stages complicated the design, layout, more possiblity of errors and no means to test it and fault find.. if i can hope to get a 5mV signal ill design for that... At least to get something working!!! I realize eventually ill need to improve sensitivity... But i need some sort of working receiver to boost my morale

[@DIlic-iz9tx]

*_BRAVO._*

[@BonsaiBrandy]

I have a loose coupler crystal radio which works great when i use my guitar amp as a speaker; the signal is very clear and i dont need to up the volume very much at all to have it extremely loud. However whenever i try to use a crystal earpiece i get nothing at all, except sometimes some white noise when i disconnect one end of the secondary coil from the rest of the circuit. Any ideas as to what could be the issue? I appreciate that description is slightly vague so if not no worries. Thanks!

[@MIKROWAVE1]

The crystal earpiece that you happen to have has such a high impedance, that the diode will not conduct. Put something like a 47K resistor across the output terminals in parallel with your earpiece.

[@hobbyrob313]

Yes please do not use parts that are almost no longer for sale??? like that RCA40468 friendly greetings from The Netherlands! Rob.

[@salimkumar9748]

Thanks sir

[@charleslauter5035]

How about using an OPamp? CAL

[@MIKROWAVE1]

Sure, high performance op-amps with a wide frequency range and low noise figure would work. You might start with an old favorite, the OP-37 in non-inverting (Hi-Z) mode, set for a gain of 20 to 30. There are hundreds of far better examples nowadays such as the LTC6226 that can give useful gain well up to 50 MHz. An ADA4084 would give a gain of 100 at 15 MHz for instance. Plenty of TI chips out there too.

[@HannoBehrens]

Between 25:00 and 25:05 is that John Paul Watson on shortwave? This was his voice, wasn't it? That's funny. I have to tune in more to shortwave. Am I wrong or why am I the only one recognizing his very special voice? It's his expression, his melody his choice of words, very special, very unique. Tell me that I'm wrong. Why was he on shortwave? Why am I the only one recognizing him ?

[@Dazzwidd]

I have a lot of new old stock 40673 FETs

[@MIKROWAVE1]

They were the king of late 70's early 1980s designs (at least for Heathkit) but are a rare beast nowadays. I have a few NOS in crumbly black foam left.

[@Dazzwidd]

@@MIKROWAVE1 Sorry, I was mistaken. I have lots of 2N4416A. I was going to offer to send you some as I have more than I will ever use but they're not 40673. I bought a few large surplus NOS lots of semiconductors off of eBay several years ago. I have a lot of 2N5109 too. They're a handy beast although for different reasons

[@Dazzwidd]

Lots of signetics NE592N14... you got me looking in my parts cases 😅

[@КоляХомяк]

Nice!

[@andersonnobre5163]

I FALL IN LOVE FOR YOUR UGLY MONTAGE!!!!!! I LOVE IT!!!! HERE IN BRAZIL WE CALLED THIS ¨GAMBIARRA¨!!!!THANK YOU FOR THIS VIDEO!!!PAX!!

[@MIKROWAVE1]

Anderson, you are elegantly describing in one word GAMBIARRA, what you mean. Literally Kludging or using what (materials and discarded electronics) is at hand to make something interesting, functional, useful and sometimes artistic, and many times produced in a digital video format.

[@josephhager1933]

Can a arduino freq.counter be used with this?

[@tubeDude48]

At 36:48 you mention the 2N918, but no schematic!

[@MIKROWAVE1]

I tried some 2N918s in the circuit. I will put up something on my FB page @Mikrowave1

[@psnpacific]

👍 Great Video! KF7NGK

[@MIKROWAVE1]

Mosfets and JFET amps are even easier - but that would be too boring.

[@johnwilson4909]

MikroWave1 What is the ISBN of the magazine you review, 101 Electronic Projects 1972?

[@dave_yeg8596]

Bruce Lee's sister.

[@Jessebaldwin-cp1hl]

blue j

[@drtidrow]

Have you considered or tried using a copper mesh as the Faraday shield? Something like this, perhaps? www.ebay.com/i/173748968607 Might need one with a coarser mesh, though.

[@ВитяЛазаренкоКонстантинови-я6й]

В данный момент занимается преподавателя в школе похоже физике, посетителей учеников сможете получать образом радиолюбитель и рамки антенны простым схемы приёмной комиссии приёмника, похожие на приставки ПКА телевизоры серии старые вижу смысла самоделки моделирующий плата разные темы для разговора учиться устройства радиосвязи мира.

[@weedeater64]

20:48 You need to make a candle powered soldering iron. 1/2' wooden dowel handle, bicycle spoke coiled around large bare copper wire. Leave enough spoke to insert into hole drilled in dowel. Heat with tealight candle. Make some flux from pine sap.

[@MIKROWAVE1]

Can I work some Obsidian or Flint into the design?

[@weedeater64]

@@MIKROWAVE1 Carve a nice totem on the wooden handle with an Obsidian/flint knife. Or now that I mention it, put a knife on the other end of the handle for scraping/cutting/whatnot. Seriously though, most of my life I've been too broke to pay attention. I recently got re-interested in 'primitive' radios. Most of my related junk is long lost, but I still have my soldering iron as described above. Just made a new alcohol burner for it from a yeast jar a short length of metal straw and a cotton ball. Works pretty good. Last night I removed all the parts from a CFL light bulb that has quit for some reason. Took about 20 minutes. Got some nice parts including a 3mH inductor I'm going to try and use as a replacement for the 2.5mH that the 'high performance regen receiver' calls for. Any tips on what I need to do to make that work, or can I just drop it in without worry?