tracking generator
I need to purchase a cheap spectrum analyzer up to 3Ghz, but I need it with tracking generator. This is hard to find at ebay at decent prices (for me). Is it possible the following combination: use a SA without tracking generator, and use as a signal source a scrap YIG oscillator ( some of them are really cheap at ebay) in the frequency band I am interested, and this one driven by a corellator between the output sweep signal and the input in the tuning coil of the YIG? Of course, it would be hard to cover lower part of the spectrum, but I am not interested in what is under 1Ghz.
/pisoiu
I can't quite picture what you mean by "the input" in your proposed correlator.
A tracking generator is a sinewave sweep output that follows the analyzer's center frequency. The frequency needs to be accurate, within the analyzer's bandwidth.
My spectrum analyzer does not have a tracking generator, but it does have a 1st LO sweep output that is 4.7GHz higher than the current center frequency. I sometimes create a simple tracking generator by connecting the 1st LO to a small external mixer and to my bench RF generator set to 4.7GHz. Maybe you can do something similar.
Thanks for reply. I am not talking about RF signal used as input in the correlator, if I remember corectly, some SA have the low frequency horizontal sweep signal (triangle) available somewhere in the back. This can be used to generate the required current for YIG tuning coil, based on a correlation table. Of course this will work for a certain setting in center freq./span, because the correlator has no way to know these settings, but it is a way to do it.
/pisoiu
Add: Look at ebay item 7549596404, picture 3 (big one), top left corner.
The 8569B is a fine classic spectrum analyzer. Remember that it is non-synthesized, so it's frequency accuracy and stability is plus or minus some megahertz. You may have a difficult time trying to match your external VCO to the drifty analyzer.
The instrument has a front-panel LO output. The 1983 HP catalog says it's 2 to 4.46 GHz at +8 dBm minimum (but doesn't mention Option 003). As a backup plan, you could probably use it with some sort of external mixer scheme.
The seller sure likes crazy colored fonts.
Happy bidding, and good luck on whichever method you use.
pisoiu,
You are wasting your time on thinking about correlators. The linearity of the YIG oscs. are about +/- 1.5 MHz at best (rather worst), and both your SA and your TG YIG oscs. have this error.
So the sum of errors are most probably takes your "TG" out of the bandwith of your SA (even apart of the errors in your "correlator").
The TG concept of echo47 is simple and works. Try that, with some simple mixing and filtering.
g579
Thanks for answer guys. Ok, considering this, I'd better start looking for a SA with TG built in. The method with YIG was cheaper, but as you said, looks complicated considering the errors. The mixing method looks fine, but I do not have a RF generator...
/pisoiu
Hi Pisoiu,
Echo47's solution is simple, cheap, and you can buid it with a few parts from the shelf. There are available VCO's and mixers from Z'comm, Minicircuits and others.
See the link below for a reference.
http://www.qsl.net/n9zia/spec/index.html
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regards,
Al
No RF generator yet? Sounds like you could use another eBay adventure! One of my best eBay buys was a Giga-tronics 600 (10MHz to 8GHz in 1kHz steps) for S310 US. The ad said "not working" but its only problem was two broken thumbwheel switches, and DigiKey stocked them.