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Old 21st Nov 2017, 11:59 pm   #1
Skywave
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Question Spectrum analyzer prices?

Yes, spectrum analyzer prices on the second-hand market: a query.
I'm not limiting myself here strictly to 'vintage' items: 'newer' items are also of interest. (But please read on . . .)
The two essential criteria are (1) spec. [to meet intended requirements] and (2) price.

Essential minimum spec.
Freq. coverage 1 - 1000 MHz
Tracking generator to match.
50Ω input Z
80 dB native dynamic range.
Front panel controls that aren't too cluttered and fairly easy to fathom out what they do!

Intended, general use.
To sweep analogue ccts. such as filters, broadband amps. and such like & to measure freq. response and return loss / VSWR; to measure the level & spectral purity of (low-level) signals from various sources.

Ideal (a.k.a. 'hoped for') price range: £500 max. (Which, of course, puts my 'want' very much in the 'vintage' category! )

As you can probably gather from all that, I'm still a bit of a novice with such items of test kit - but I know that an S.A. is not going to be particularly cheap!
Hence, my generalized query: I just need some basic guidance. I hope the above does indeed make sense.

All comments will be appreciated.
Al.
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Old 22nd Nov 2017, 12:20 am   #2
Wendymott
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Default Re: Spectrum analyzer prices?

Hi Al..... On my retirement..... as in "funds a plenty". I bought a Spectrum analyser with tracking generator, "sorry I cannot remember the make" this was a "Scope tube" type, and although it was VERY useful, The Rogol DSA815 came available the next year.. "2015", and has been a VERY useful piece of kit ever since. I have no connection with the suppliers, I bought from Ebay, but was supplied from a UK warehouse. As with everything..it all depends upon your funds available, and whether you want vintage or something to do the job. I am still finding things this can do, such as Fourier transforms, measurements with marker cursor.. It has pride of place in my workshop, and is a treasured addition.
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Old 22nd Nov 2017, 12:45 am   #3
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Default Re: Spectrum analyzer prices?

The Rigol is a possibility, but the new price is a bit over double your budget. It ofers a lot of digital enhancements and features - softwear is cheap to reproduce once it's been written and the manufacturer has chosen the sell lots at low cost route rather than sell it dear at large mark-ups route. the main negative point is that the local oscillators seem to be based on wide range VCOs and suffer fairly poor phase noise compared to classical analysers with YIG tuned oscillators.

Your budget rules out the HP 859x and HP 856x family unless you happen on a very lucky bargain.

However the earlier family of analysers made of plug-in uniits in the HP140T crt mainframe fit the budget.

They're actually very good and RF plug ins are common for 110MHz and 1250MHz ranges.

The 1300MHz tracking generator to match it is also fairly common.

They are a very good box to learn on, with three-knob control of the main parameters.... fully manual. but with a light to warn you when you're sweeping too fast.

Beware of ruined storage CRTs, they are irreplaceable.

There is also the hP8558 analyser family which plugs into the 180 series scope mainframe. One might fit your budget BUT though the may seem a bit more modern than the above, avoid them. They don't have a tuning stabiliser and drift like the devil is after them. Best avoided. Tektronix's scope plug in type spectrum analysers are pretty much similar.

Various makers do handheld units that they call spectrum analysers, but they are a bit too limited, really.

It all comes down to what turns up. For real bargains you need to be either plain lucky or buy something needing fixing.

David
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Old 22nd Nov 2017, 1:24 am   #4
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Default Re: Spectrum analyzer prices?

My concern would be that I think you want to use the instrument to help you evaluate designs like the ones on the recent JFET voltmeter threads.
For stuff like this you (ideally) need something that can be configured to minimise measurement uncertainty. There are so many things that can cause false results on a spectrum analyser. Adding a tracking gen into the equation can make things even worse in terms of measurement uncertainty.

If you were just doing casual stuff like checking ham radio gear for obvious spurious terms or looking at offair signals then you could get away with a fairly average 20-40 year old instrument and it would be within your budget. But even for semi serious design or verification work, most analysers in this class aren't really up to the job. You could easily find that the analyser uncertainty is MUCH worse than the thing you are testing in terms of frequency response/flatness or spurious free dynamic range. So you could find it to be a confusing or frustrating experience if you get unexpected test results because the analyser isn't up to the job in hand.
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Old 22nd Nov 2017, 1:51 am   #5
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Default Re: Spectrum analyzer prices?

There's an fairly old youtube video here showing the limitations of the Rigol analyser and its tracking generator.

https://www.youtube.com/watch?v=fiqxaU8imA0

I'm not sure if this is a typical example of this instrument but you can see it is troubled by tracking gen leakage that causes fairly significant (summing and cancelling) ripple on signals just 60dB down. Add to this the fact that the port VSWR is going to be poor on these cheap instruments. So to minimise mismatch uncertainty at the ports you would need to add attenuators to the ports. But this brings you closer to the leakage issues and you end up with a restricted dynamic range because of this.

I think the newer Siglent SSA3021X analyser is a similar price and it performs a lot better in this respect. But it is still a budget class analyser so will need to be used with care to manage uncertainty issues. It's priced at about three times your budget limit. But it is a very popular choice for hobbyists who want a modern analyser with reasonable RF performance and a nice big modern display and modern connectivity and features.
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Old 22nd Nov 2017, 7:01 am   #6
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Default Re: Spectrum analyzer prices?

I have a Marconi TF2370, one went on ebay a week or so ago for £180, it may not cover all your specs though.

I was watching a Youtube video last week where the chap posited the view that he wouldn't bother with an actual SA, but would buy a PC version, saying in his opinion PC version's can do all and better anything an actual SA can do. No idea if this is true or not, but there are several PC based analyser's (audio,network etc) AFAIK that do the job very well. Might be worth a look Al, before you buy a girt big lump of test gear.

Andy.
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Old 22nd Nov 2017, 8:55 am   #7
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Default Re: Spectrum analyzer prices?

Quote:
Originally Posted by Radio Wrangler View Post
They don't have a tuning stabiliser and drift like the devil is after them. Best avoided. Tektronix's scope plug in type spectrum analysers are pretty much similar.
That's not strictly true. I have a Tek 7L12 plugin which definitely does have frequency locking, up to a point, though it's still a somewhat cantankerous beast. I mostly use it for rough-and-ready EMC sniffing, though, which is hardly a demanding application.

I think the initial problem with the Tek spectrum analyser plugins is that they're not as common as they might be and command rather high prices for their capabilities.

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Old 22nd Nov 2017, 10:16 am   #8
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Default Re: Spectrum analyzer prices?

Another problem with the Rigols (I had the 3 GHz one for a few years) is chronic phase noise. It made a mockery of the boasted 10 Hz RBW. Trying to sweep a narrow filter was not a happy experience.
I now have a Signal Hound combo - the SA44b analyser and (bought later) the separate TG44a. It's PC controlled via USB and the latest software is excellent. Phase noise is about 40 dB better than the Rigol.But the price for the two units will be over £1000 and you'll need a decent PC to run it.

https://signalhound.com/products/usb-sa44b/
https://signalhound.com/products/usb-tg44a/
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Old 22nd Nov 2017, 12:34 pm   #9
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Default Re: Spectrum analyzer prices?

It really is fun reading all the differing comments...... from the serious professional engineer to the down right "amateur" like me. I was surprised that I was the first to comment. As I said the Rigol is fine for such as I need, and in many cases what anyone would need, however I again thank Jeremy for pointing me to the youtube features. I have spent the last hour adding various instructors into my favourites.
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Old 22nd Nov 2017, 6:00 pm   #10
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Thumbs up Re: Spectrum analyzer prices?

O.K. - lots of useful comments and guidance in the above: thanks, everyone.

I strongly suspected that my cost limit was not reasonable - but I thought I'd ask anyway! However, what I have now learnt - which is of use - is that the Rigol DSA815TG looks like an eminently suitable item. Now all I have do to is start saving up for one!

Again, my thanks to everyone.

Al.
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Old 22nd Nov 2017, 7:42 pm   #11
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Default Re: Spectrum analyzer prices?

From the "cheap" end of the scale, I have a little handheld gadget called an RF Explorer. It has it's limitations, but for the price it is pretty good, and truly portable. It has been used for quite a number of tasks that I would use a proper analyser for, and although it doesn't have a tracking generator as such, the display gives a frequency and level readout over the peak, which is close enough for my purposes. Unfortunately I had to leave my favourite spectrum analyser at the last job, so this is an affordable substitute. It has done everything I have asked, and will happily cover up to the 2.4GHz/WiFi band. Not a professional instrument as such, but good for the price.
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Old 23rd Nov 2017, 11:45 am   #12
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Default Re: Spectrum analyzer prices?

I Agree with Alan,

The RF explorer is really good value for money. There are several versions available. I've had mine for a number of years & it has served me well. There is now a tracking generator available for it.
There is also an LF version, recently on the market.

David.
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Old 24th Nov 2017, 12:22 am   #13
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Arrow Re: Spectrum analyzer prices?

Quote:
Originally Posted by G0HZU_JMR View Post
My concern would be that I think you want to use the instrument to help you evaluate designs like the ones on the recent JFET voltmeter threads.
For stuff like this you (ideally) need something that can be configured to minimize measurement uncertainty. There are so many things that can cause false results on a spectrum analyzer. Adding a tracking gen into the equation can make things even worse in terms of measurement uncertainty.
Well since you mention it, that JFET voltmeter design attempt went 'cold' for two main reasons, (1) 'Things domestic' - and unrelated to any of the topics relevant to this forum - took precedence on my time, etc. (2) Later, I subsequently realized that my measurement technique was poor and leading me to draw erroneous conclusions. But now that the winter is upon us (or near enough!), it's been pulled of the 'round-to-it' pile for a re-appraisal - and I'm now feeling just a little more optimistic about it.

Al.
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