EMRFD Message Archive 5472

Message	Date	From	Subject
5472	2010-11-28 13:25:27	klopfensteinrex	Spectrum Analyzer Waveform Question.
I built 1998 QST spectrum analyzer several years ago. I recently change the log amplifier to the new design using the AD8307AN. I changed the IF to 10.7MHz and added a 30KHz BW crystal filter. I seem to have acquired an anomaly in the peak of each frequency "spikes". As the display reaches the peak, if falls off a little (2-3dBm) and then continues to raise to peak. The effect is a dual peak with the first a few dBm lower than second. Any ideas where to look? Rex Klopfenstein KC8PFP Bowling Green, OH
5474	2010-11-28 15:46:41	Thomas S. Knutsen	Re: Spectrum Analyzer Waveform Question.
Do you have an tracking generator? Is the problem there in both banwiths? 73 de Thomas. 2010/11/28 klopfensteinrex <klopfensteinrex@yahoo.com> > > > I built 1998 QST spectrum analyzer several years ago. I recently change the > log amplifier to the new design using the AD8307AN. I changed the IF to > 10.7MHz and added a 30KHz BW crystal filter. > > I seem to have acquired an anomaly in the peak of each frequency "spikes". > As the display reaches the peak, if falls off a little (2-3dBm) and then > continues to raise to peak. The effect is a dual peak with the first a few > dBm lower than second. > > Any ideas where to look? > > Rex Klopfenstein > KC8PFP > Bowling Green, OH > > > -- Please avoid sending me Word or PowerPoint attachments. See <http://www.gnu.org/philosophy/no-word-attachments.html> [Non-text portions of this message have been removed]
5476	2010-11-28 17:14:37	Rex Klopfenstein	Re: Spectrum Analyzer Waveform Question.
Thomas I do have a tracking generator. I still have to change its IF to 10.7MHz. I have a separate toggle switch for tracking generator power and it is off. I am trying to get the 300KHz BW working first. I did notice that I get a similar results with 30KHz BW except that the first peak turns into a spike on the skirt and the second hump is the 30KHz peak. Rex Klopfenstein KC8PFP Bowling Green, OH ________________________________
5477	2010-11-28 19:39:50	Kerry	Re: Spectrum Analyzer Waveform Question.
Could just be overload; reduce the input to the SA by 10-30dB and see if the "wrong" peak disappears.
5491	2010-11-29 17:28:41	Rex Klopfenstein	Re: Spectrum Analyzer Waveform Question.
Kerry I see the 'dip' when I connect my HP8640B set to -30 & -40 dBm. Thanks Rex Klopfenstein KC8PFP Bowling Green, OH ________________________________