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.
I do not have a ZTX690B in my junkbox.
ReplyDeleteWhere can I buy such an exotic or can I replace it with something more common?
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.
ReplyDeleteIMO they made by zetex.
ReplyDeletewww.diodes.com
Enter ztx690b in the 'search' field.
73!
Yes LY2SS, you are correct. They were made by Ferranti originally I believe.
ReplyDelete