TRF PART 2

[@marknesselhaus4376]

I remember from years ago at a local AWA meet that there was a contest for the smallest home brew tube radio and I just happened to have a couple of submini's and wired up a very poor but tiny circuit that actually worked and won the contest. Think I won a coffee mug :-)

[@MIKROWAVE1]

Gee I was thinking a bottle of single malt. But a mug. Okay

[@marknesselhaus4376]

@@MIKROWAVE1 Yeah, a bottle of brew would have been nice Lol

[@benthere8051]

I use scraps of copper clad G4 for my prototyping. I space-wire all of my components. There's always a ground plane right there. The bypass caps are always no more than a few tenths of an inch from a good ground. If I need to shield a portion of the circuit, I cut pieces of PC board material and solder them into a box around the sensitive circuit. I haven't done work as low a 1 MHz in a long time. I need to get some experience with low frequencies before I comment much more. I learned my prototyping techniques from a good friend that can do microwave stripline designs in his head. At those frequencies, a wiggle in a PC board trace is a component and Ls and Cs are patterns on a PC board. I made a 315 Mhz super regen receiver once whose reactive components were just patterns on an FR-4 PC board.

[@MIKROWAVE1]

Excellent build method!

[@Radio478]

Very encouraging video thanks 😊

[@PapasDino]

Great way to spend a Sunday afternoon! TNX Mike! 73 - Dino KL0S

[@mikepasko7493]

Great work.........

[@user-ri5nj4sz5m]

Классный приёмник я спаял на лампе 6к14б-в выход сделал с катода а анод на + непосредственно получился катодное детектирование работает как гетеродин👍👍👍

[@ingussilins6330]

Slide tuning coil can work without external antenna, if it use as a part of LC tank ( variable inductor ). Slide tuning coil works as a "magnetic loopstick antenna". Receiver - TRF with infinite input impedance.

[@MIKROWAVE1]

with no wire antenna the Big Coil or Long Ferrite Rod = Big Signal.

[@albertodelrio9206]

Genial !!! Más vídeos de trf !!

[@margaqrt]

Thanks for doing a better job with schematics on screen. Though links in descrip might be preferred by some, this is totally servicable.

[@hobbyrob313]

very nice video! I hope another part 3? shortwave? again friendly greetings from the Netherlands! Rob

[@tonychristoph1063]

very good idea ! for the future . regenerative receiver for medium and shortwave and also improvements for all of them thank you mikrowave1

[@defaultuser000]

Just found your channel. Great content and very informative. 👍

[@MIKROWAVE1]

Welcome and have fun building some old time stuff.

[@mohinderkaur6671]

For the transistor circuit, drive the base from 1 turn coil. Bias at 1ma to 3 ma. remove the emitter follower stage. gain can be controlled by reducing the bias current. Should be very stable . Bipolar IF amps obtain stability by mismatching the input circuit and driving from a very low impedance - 100 ohms or so. Want even more stability? drive it from the emitter and ground the base to rf.

[@scharkalvin]

1U4 is a SHARP cutoff pentode. The 1T4 is the remote cutoff type.

[@n8nkqrp595]

At least in QRP transmitters, I'm a firm believer in the use of ferrite beads on the bases of all oscillators, drivers, and PA stages. Wonder if it would knock down VHF+ parasitics in your Rx? Oops. I need to shut up until you've finished! How rude! Amazing videos you make... just spectacular. I tell my ham friends about your work. Take care and 73 OM

[@glenngoodale1709]

Thank you for the video

[@wadepatton2433]

First radio video that made me think of Propane & Propane Accessories. Yup.

[@MIKROWAVE1]

Honestly my dad used to install, repair and deliver propane.

[@gabevee3]

Putting the 1k after the amp (or input to crystal radio) reduces its overall gain by paralleling with the 2.7k collector resistor. You effectively made the collector resistor 729 ohms, coupling caps and antenna coil notwithstanding.

[@Jeffrey314159]

0:26 "Exult the station"? Don't you mean 'emphasize' the carrier frequency? 2:18 The threshold of instability.

[@MIKROWAVE1]

Exalted carrier Reception or ECR simply put, it’s when you tune in an AM broadcast using the SSB mode on your radio. Sound impressive huh? The effect is more dramatic on a regen that is critically oscillating. The AM locks in.

[@DAVIDGREGORYKERR]

If you are going to use vacuum tubes then what about using TELEFUNKEN Space Charge tubes that will work from 12V-45V with a 3V heater, you can use common base operation and use the emitter lead as the input and the collector as the output side, ECC88 tubes can be used at voltages from 12V-50V.

[@mktwatcher]

Did you consider mounting the coil on the crystal radio at a right angle to the coil on the RF amplifier module to discourage induction feedback?

[@MIKROWAVE1]

Excellent practice. Of course building on a ground plane and actually using a shielded enclosure would be nice!

[@MichaelOfRohan]

In the beginning you were playing with the regen and the speaker started screamin. My lm386 amp does the same thing! Why?!

[@jordandobrikin8611]

What Tubes would recommend that use lower B+/Plate voltages

[@MIKROWAVE1]

There are special low voltage "space charge" tubes specifically designed to work on 12 to 15 VDC. These were developed for car radios just before transistors. Most tubes will work on lower plate voltages. People use tubes like the 12AT7 dual triodes or 6BA6 pentode at embarrassingly low voltages like 25 V to 40 V.

[@ablebaker99]

Great videos! Since you have shown BJTs and tubes, what about FETs in the TRF?

[@MIKROWAVE1]

FET's and mosfets are very popular and are very common in TRF circuits. I will do one up for an SDR front end in a video. Heck why not a selective converter for HF with FET's for your SDR to really wake up?

[@donatoloprete5816]

Ciao una domanda la VALVOLA Philips 1905 VOLT alimentazione??? Aspetto risposta grazie 🔌💡1905 ~ volt?

[@glenngoodale1709]

Did you ever do a video on serviceing a DX 160 ? I get some AM but as I go higher up the bands I don't get much

[@BruceNitroxpro]

You might want to WAIT a BIT longer for a circuit topology which allows testing without having to "hand pick" the active device, due to instability, like the ones which come next. LOL I must say your topologies get more and more curious!

[@MIKROWAVE1]

I am invariably unstable.

[@BruceNitroxpro]

@@MIKROWAVE1 , I simply haven't a rejoiner to that! (rolling my eyes!) I tried to spell, "Curiouser and curiouser," but failed out of the gate!

[@tubeDude48]

At 6:22 I think you meant Cascade. Great video though!

[@MIKROWAVE1]

Wow you guys are so awesome. I am working fast on these and make mistakes. But in this case cascode is the correct term for the typical common emitter into a common base series configuration that is the standard in high isolation low noise RF preamplifier design. Check out the realistic DX150 all bipolar schematic. They went to fets with the same topology in the 150A 160 etc..

[@seanross1732]

@@MIKROWAVE1 whats the specs of the coils on the 1 tube rf amplifier and crystal set, what size wire, / wooden dowel and turns and taps

[@ronaldphillips311]

I used to enjoy making crystal sets as a boy but have no interest in adding amplifiers it detracts from the original idea.

[@MIKROWAVE1]

Ah the true Crystal Set purist is here! There is always something interesting to learn with those things.

[@ronaldphillips311]

@@MIKROWAVE1 Thank you.