Chitika: regen

Showing posts with label regen. Show all posts

Several people have e-mailed me suggesting that the weird echo I have been hearing on shortwave broadcast stations is in fact one of the fabled "Long Delayed Echoes" that radio amateurs have been hearing intermittently since about 1927. I was skeptical at first, but -- at least in the case of the Radio China signal -- I think LDE caused by the signal going around the globe several times does explain what I've heard. Each trip would add a delay of about .133 seconds, and that seems to match what we hear in my recording:

http://soldersmoke.blogspot.com/2014/08/strange-echo-on-china-radio.html

Compare that with what K9FIK recorded on 10 meter SSB (thanks Stephen!):

http://swling.com/blog/2013/10/hearing-the-speed-of-light-dx-double-echo/
(you can listen to the audio on this one).

It sounds very similar.

If this is in fact LDE, I'm lucky -- this is pretty rare. And it is a eerie that I first heard it on on Regen receiver from the 1920s! Above is a picture of the regen used to study the FIRST LDEs. See: http://folk.uio.no/sverre/LDE/

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

SolderSmoke Podcast #165 is available:

http://soldersmoke.com/soldersmoke165.mp3

September 13, 2014

Workbench Update: Bill's "Off the Shelf" Regen, Pete's Boatanchors
Mysterious Echos on Shortwave Signals. Solve the Mystery. Please.
Microcontrollers -- What they can do for you.
Small world: As a kid, Pete was neighbor of "Digital Dial" N3ZI
NEWS FLASH: Arduino creator Massimo Banzi was a ham!
Born in a bar, cheaper than pizza: The Italian origins of Arduino
Arduino CW generators
No coding skills needed
Arduino + AD9850 = Signal Generator or VFO
Arduinos in the Minma
What the heck is a Shield?
SolderSmoke Mailbag

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

Tony, VE7JUL, wrote in asking for a schematic on the "Off the Shelf" regen. Here you go Tony. Nothing fancy or new here. All the credit goes to Howard Armstrong, Charles Kitchin and Jay Rusgrove!

Even though they seem much simpler than other receivers, I think regens are in fact more of a challenge than, say, a Direct Conversion receiver. Be prepared to do a lot of fiddling around with the coil and the tuning and regen capacitors. Think of that detector stage as a VFO, a VFO that you want to be able to smoothly take out of oscillation.

Here's a tip on regen debugging: Once you have it built, hang a high impedance 'scope probe off the drain of the FET and watch the scope/counter as you move the main tuning cap and the regen control. This will give you a visible indication of where (on the regen control) the stage is going into oscillation. A freq counter (I have one inside my Rigol 'scope) will let you know what frequency range you are operating on. You may end up having to make adjustments to the coil, adding or taking away turns to get into the proper frequency range, or to the desired level of feedback. Pay attention to the phasing of the coil turns. You may also find yourself adding capacitance in series with the regen and main tuning controls (to reduce their tuning range) or adding capacitance in parallel with the main tuning cap (to lower the entire tuning range if necessary).

Build it solid and strong! It is, after all, an oscillator. Be prepared to do a lot of "noodling"

Hi Bill,

This receiver with just 4 transistors and no chips looks really interesting to me. Do you have a schematic that you could either flip to me or point me to? Getting my hands on some air variable caps may be a challenge, but I can 'noodle' something out on that.

Love the podcast, blog and really enjoyed the SolderSmoke book - thanks for your continuing efforts to share with the amateur radio community.

73/72
Tony

VE7JUL

the little red dot at Coquitlam, British Columbia on what used to be the Clustr map (but is now a Revolver map)

A few weeks ago I noticed a strange echo on Radio China International's signal. If you scroll down a bit you can see my YouTube recording of the problem. On one of the SWL lists, there was speculation that this problem was the result of a flaw in the RCI digital studio gear. But then a few days ago I heard it again on RCI -- surely the tech-savvy Chinese would not have let this kind of problem persist for weeks.

Today I heard the same effect on a very different SW station -- this one an the 24/7 fire and brimstone broadcast that appears at many points on the dial. The effect is very similar to what I heard on RCI.

So OK all your shortwave gurus: What is going on here?

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

Chitika

Long Delayed Echo on Radio China International

SolderSmoke Podcast #165 Arduinos!

Schematic for "Off the Shelf" Regen

Shortwave Echo Mystery on Yet Another SW Station. What is this?

AHMED HASSAN MOHAMMED

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