Matjaz Vidmar Spectrum Analyser

The design for this spectrum analyser was published in the magazines 4/1998 to 4/1999, they are too big to be included as downloads here, but they can be ordered as back issues. It has proved to be one of the most popular projects, I have sold many sets of PCBs. It is a very ambitious project and I have been asked by several constructors to start a page on this web site to exchange ideas and to locate some of the more difficult components. Please email me with your questions and I will start a full FAQ section.

I have received two emails about the construction of the spectrum analyser and one about an associated topic:

From Geoff Pike

I started taking the magazine because of this article and I thought it was a breath of fresh air, however I hope the following is of some help to others and to myself if the problems can be sorted out.

The heart of the unit is of course the wideband VCO with out this working correctly you can forget the rest, and the rest realistically is very straightforward.

The 1st IF cavity filters presented no problems, then I carried on with the VCOs here are were I got my parts

1) 1/16" PCB is almost (for me) unobtainable, I got mine from Chris Towns via a packet enquiry, he could not remember were he got it!!

2) The BFP 420 is I think still available from Farnell but they use the Infineon # Q62702-F1591 and Farnell# 3006591

3) Varicaps from RS Components 288-395 ie BB833

4) I used mixer diode BAT 15-099 from RS Components 288-480

5) Pin diodes etc. from RS Components I think I used BA585 and BA792 RS 288-430 and RS 226-5322

OP amps SMD caps etc not a problem, but getting the VCO to go past about 1.6 , 1.7Ghz was impossible.

Hope this of use, and beware that Farnell carry some interesting stuff but they use manufacturers part# and not the BFR or BFG or BFP type numbers

Regards
Geoff Pike
GI0GDP

From Patrice Soutoul

I am Patrice Soutoul, F1GIU. I live close to Toulose South France. I have built the spectrum analyser plus tracking, Digitiser, marker counter and a 26GHz extension. I have had very difficult problems with the VCO and required some help from Matjaz and his friend Darko Volk and am waiting for some answers but I think it is a design problem. If you need help wit coils or crystals please ask me.

Best Regards
Patrice
F1GIU

From Hans Matthaei, PA0HSM

Hans is looking for an English version of an article by Darko Volk, S57UUD, published in CQZRS April 2000. The article was about a microprocessor controlled VCO.