10 Mar 2010

9kHz band receiver front-end (M0BMU)

Jim M0BMU has produced a neat loop/preamp design suitable for listening on the 9kHz band for which we hope NoVs will be available shortly in the UK. His design has sufficiently low noise to provide a state-of-the-art receiver for this band when used with the many excellent software based VLF receivers such as Winrad and Spectrum Lab. This circuit was posted on the LF Reflector this evening.


PA3BCB said...

I do not have a ZTX690B in my junkbox.
Where can I buy such an exotic or can I replace it with something more common?

Roger G3XBM said...

I think any reasonably low noise, high signal transistor would do. The ZTX690 devices were commonly available transistors made by Ferranti in the 1970s and 1980s.

LY2SS said...

IMO they made by zetex.

Enter ztx690b in the 'search' field.


Roger G3XBM said...

Yes LY2SS, you are correct. They were made by Ferranti originally I believe.