Barkhausen Oscillations

[pwdrive]

Barkhausen oscillations, most veteran TV techs will remember this and it's effects on the picture but I am wondering if anyone has linked this effect with spurie in HF receivers ie: is it possible, not sure, possibly in the local osc stage as the conditions "might" approach what's needed for Barkhausen oscillations ? Or am I fantizising...

Lawrence.

[Les G4CNH]

Hi Lawrence, in the past I have found this oscillation mainly around high power stages. I built a small transmitter many many years ago but when keyed up the screen grid glowed quite brightly due to the presence of BK as we called it. Never did cure it so built another circuit in the end.

[Skywave]

Barkhausen oscillations and what is known as the Condition for Barkhausen Oscillation are two separate but related topics. The 'Net deals with both, (q.v.), but as for Barkhausen oscillations, the following is a simple-to-understand article.

http://www.smeter.net/daily-facts/7/fact22.php

It's interesting to note that F. E. Terman discusses what is a very similar arrangement (without a reference to Barkhausen) in this book 'Radio Engineering' (Mc. Graw-Hill, 1932) pp. 351 - 352. His name for that valve configuration is the 'Inverted Vacuum Tube'.

Al. / Skywave / Oct. 2, '13 //

[pwdrive]

Yes, a curse on the old TV screens especially on weak signals.

Lawrence.