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Spectrum Analyzer or 'Field Strength' Analyzer?

post #1 of 27
5/25/06 at 7:59am
Thread Starter 
This is a tough question since because of the difficulty of describing exactly what I want to accomplish and how I would use the device.
I probably considered this more 'hobby' use, but for the pratical side and how it relates to this forum is for tuning channel traps to reduce overload from local transmitters without impacting 'desired' signals.
I have locals 7 miles away that 'swamp' my amp that are 'killing' desired reception of stations 55 miles away in the same direction.

I do have a SLM that does have a spectrum 'graph' display, but the resolution is poor and it really doesn't make the grade here. Without spending big bucks to get a 'lab quality' spectrum analyzer, I have found these priced between $875 and $3300;

http://www.protektest.com/ProdInfo.asp?prodId=3201
3201 is $1400 & 3290 is $1900 (with 2.9 GHz coverage)

http://www.instek.com/GSP-810.htm
Which is the same as this for $1675;
http://www.mcminone.com/product.asp?...6&info=details

http://www.instek.com/GSP-827.htm
The step up LCD model w/ 2.7GHz coverage ($3270);

http://www.bkprecision.com/www/np_specs.asp?m=2630
Made by Atten for $1900 which is the same as this for $1030 delivered;
http://www.madelltech.com/m1-7.html

http://www.avcomofva.com/products/de...p?page=psa37xp
For $3270 (only US made model)

The Protek models are "Field Strength" Analyzers and the Instek (Tenma/MCM Electronics), B&K (Madell/Atten), and AVCOM models are true "Spectrum" Analyzers.



Models & prices have been updated.
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post #2 of 27
5/26/06 at 5:42am
Thread Starter 
Thanks for the reply, but that has nothing to do with the issue as they are two different devices. This is a T&M (test & measurment) issue. The unit would not be exclusely for measuring TV signals (or I wouldn't even bother with this).

1. I have 3 different amps and they are preform about the same (overload wise).
2. I don't use preamps since they are designed to be outdoors at the antenna where you can't get at them and since the filters have to be ahead of the preamp, it makes them inaccessible also. Double whammy.
3. My downlead from the antenna is only 15' into the attic so a preamp isn't what I would use.
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post #3 of 27
5/26/06 at 6:01am
Thread Starter 
For a update on the original post. I have found that the MCM (Tenma) unit is actually this (but $400 more).
The difference is support or lack of it from MCM;

http://www.instek.com/GSP-810.htm

that and the AVCOM 37XP are newest of the models I listed. The AVCOM 65c, the Protek 3201 and the B&K 2630 are the oldest. The B&K seems to be the most limited in features of the true "Spectrum" Analyzers (also considering it's age) and while the AVCOM 65C is popular in the 2-way communications field, but a few hundred more gets you the newer and full coverage LCD screen 37XP. It's really more than I wanted to spend, but obviously, the 37XP is the best of this bunch and the most expensive.

I just don't know if that Protek 3290 would fit the bill, being a 'different' (cheaper) type of analyzer.
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post #4 of 27
5/26/06 at 9:30am
Thread Starter 
Quote:


Have you ever tried phase cancellation to correct overload issues

I have too many channels that would have to be dealy with using other antennas.
Quote:


It is not possible to remove the interference with conventional filtering techniques without also destroying the desired signal.

Not if the filters are tuner correctly.

I don't have a problem with multipath. I will look into that preamp, but with 3 carriers between +45-50 dbmV, I doubt it would handle them.

Thanks for the input, but I would perfer to get back to the orginal issue of what to get.
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post #5 of 27
5/26/06 at 1:03pm
Quote:
Originally Posted by videobruce View Post

This is a tough question since because of the difficulty of describing exactly what I want to accomplish and how I would use the device.
I probably considered this more 'hobby' use, but for the pratical side and how it relates to this forum is for tuning channel traps to reduce overload from local transmitters without impacting 'desired' signals.
I have locals 7 miles away that 'swamp' my amp that are 'killing' desired reception of stations 55 miles away no less in the same direction.

I do have a SLM that does have a spectrum 'graph' display, but the resolution is poor and it really doesn't make the grade here. Without spending big bucks to get a 'real' spectrum analyzer, I have found these priced between $1400 and $3700;

http://www.protektest.com/ProdInfo.asp?prodId=3201

http://www.mcminone.com/product.asp?...6&info=details

http://www.bkprecision.com/www/np_specs.asp?m=2630

http://www.avcomofva.com/products/de...sp?page=psa65c

http://www.avcomofva.com/products/de...p?page=psa37xp

The Protek models are "Field Strength" Analyzers and the Tenma (MCM Electronics), B&K and AVCOM models are true "Spectrum" Analyzers.

While the Protek is the cheapest solution ($1400 for the 3201 and $1900 for the 3290 w/ wider freq. coverage), I don't know if they are really the best choice. The Tenma is $1750, the B&K is $1900, but are limited to freq. coverage. The AVCOM models are the most expensive; $3700 which is more than I really wanted to spend but haven't ruled them out all-together since the freq. coverage is greater and it's a LCD screen.

I also would have use for the ability of 'probing' the 2.5 GHz band for Wi-Fi & satellite applications, but that eliminates the lower cost choices.

The Protek is junk. My company bought one hoping it would be usable for portable applications. We find it to be totaly useless. We also have an IFR-8000 which is old but a good work horse. I really like the small Anritsu's but those dudes are expensive.
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post #6 of 27
5/26/06 at 1:17pm
Thread Starter 
Other than the "junk" part, would you expand a little on that?
What exactly are the application(s)?

Anritsu, HP, Tek, R&S etc. I would not consider because of price.
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post #7 of 27
5/26/06 at 2:42pm
Quote:
Originally Posted by videobruce View Post

Other than the "junk" part, would you expand a little on that?
What exactly are the application(s)?

Anritsu, HP, Tek, R&S etc. I would not consider because of price.

It was purchased for use in the land mobile industry to look at site noise, radio signal, etc in the field. I have used many spectrum analyzers over the years, but when I pickup up this thing, it was like a foreign object. The interface was not intuitive at all (in fact it was counter intuitive). It's nearly impossible to look at the screen and figure out how it is setup. What mode is in; what's my center channel, resolution band width, units per division, etc? Who could tell? Part of the problem is that the screen is so tinny you can't read anything and most of the time there is nothing to read. I thought it was just me so I gave it to someone else to use. They couldn't get anything useful out of it either.

As just a field strength/RSSI meter and scanner, it seems okay, but I didn't think it was functional as a spectrum analyzer. You would have to see it in action to understand how bad the spectrum analyzer features are. Can find one in a store and check it out yourself?

Maybe everyone else likes it and I'm just an idiot. It wouldn't be the first time.
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post #8 of 27
5/27/06 at 7:06am
Have you determined if filters are available with skirts sharp enough and insertion losses low enough to notch out adjacent channels and still give you enough usable signal from desired stations? While I haven't been active for several years it used to require a signal generator as well as a spectrum analyzer to align filters, also be sure all impedances match the antenna system. These were problems encountered at two way radio repeater sites. Buying test equipment without checking out filter sourses and costs first could be a mistake.
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post #9 of 27
5/27/06 at 7:14am
Thread Starter 
Quote:


As just a field strength/RSSI meter and scanner, it seems okay,

RSSI?? Do you mean RTSA?
Thanks for that input that is on target to the question. Are you comparing this sub $2k unit with a laboratory grade $20 or $40k unit??

They elected use the term "Field strength" instead of "Spectrum", but I don't know of any clear division of either term. Monitoring Times (Grove Ent.) did a review back in '99 or '00 and mentioned the front end being less than desirable.
Quote:


Have you determined if filters are available with skirts sharp enough and insertion losses low enough to notch out adjacent channels and still give you enough usable signal from desired stations?

Yes there are, but the better ones are too expensive. I already have the traps, I just need a better way to re-tune them with a better display.

For those who missed the big picture, this isn't the only reason for the purchase, just one that fits this forum.
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post #10 of 27
5/27/06 at 7:28am
Thread Starter 
The only reason it was mentioned in the first place was to give a idea on how the device to be used. Nothing else.
The title isn't: what filter to buy.

Update on pricing; that Instek 810 can be had for the same price as the Tenma/MCM unit for $1750 delivered. I wish they would offer a freq. extender for 3GHz as a option. Also, the AVCOM 37XP can be had for just over $3200, but that is really more than I wanted to go.
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post #11 of 27
5/27/06 at 7:58am
Again only speaking from past experience either piece of equipment's front end frequency selectivity is too broad to be preclude overload just as your preamp, additional equipment is required.
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post #12 of 27
5/27/06 at 8:00am
Quote:
Originally Posted by videobruce View Post

RSSI?? Do you mean RTSA?
.

RSSI is probably more of two-way radio term, "Received Signal Strength Indicator". It's generally accepted to mean signal strength (power) in dBm, but that is not the literal definition. It is really just a graduated numerical scale that indicates relative signal strength. It is normally translated to power in dBm based on some calibration curve internal to a measurement device. dBm by definition is power expressed in dB referenced to 1 milliwatt.

"Field strength" is very different. I would have to go back to the text books to define it correctly, which I am too lazy to do right now. Seems like it's expressed in micro-volts/meter (uV/m) and/or in dBuV/m. As recall field strength is frequency dependent when related back to the power in dBm.
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post #13 of 27
5/27/06 at 9:43am
Thread Starter 
Others suggested the 'used' market. Problem is, most of those are the above $10k units or older boat anchors. Other problem, those model numbers are too way to confusing since there are literly hundreds of models out there.

Here is the Protek review;
http://www.monitoringtimes.com/html/...ws.html#Protek 3201 RF Field Analyzer
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post #14 of 27
5/27/06 at 9:54am
The Protec doesn't seem to have the resolution you desire, and the specs on the Tenma don't seem to say what the sweep resolutions are, but the other three are suitable for your broadcast, notch tuning needs.

Realistically, anything with a sweep resolution of 100 Kz or finer will allow you to tune a notch trap to do as much as it can be tuned to do. I have one older AVCOM that only allows me to select between 3 Mz and 300 Kz which is useless for tuning FM single station attenuator notches, but even my primitive Blonder Tongue BTSA-5 lets me tune them as well as they can be tuned.

One pain in the butt aspect of my AVCOM, which I think is a model 33, is that when I adjust the span, the amplitude has to be reset against the reference spike, whereas on my Blonder Tongues, it requires no adjustment. I don't know if the current model AVCOMs need to have their amplitude referenced to their scan width, but that won't impede using them to fine tune notch filters, since the only important parameter will be the relative attenuation introduced

What channels are you trying to notch and what channels are you trying to sustain? Can you live with two downleads, one for receiving the strong stations and one for the weak ones? To develop the maximum attenution of the stronger channels, you will sometimes wind up degrading them such that they are not recoverable.
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post #15 of 27
5/28/06 at 5:36am
Thread Starter 
Quote:


anything with a sweep resolution of 100 Kz or finer will allow you to tune a notch trap to do as much as it can be tuned to do. I have one older AVCOM that only allows me to select between 3 Mz and 300 Kz

I take it you mean 100 kHz or finer and between 3MHz & 300 kHz. The Instrek (Tenma) has a Resolution B/W down to 3kHz and the AVCOM 37XP down to 75 kHz. Since the Protek is different, there doesn't seem to be a reference of 'Resolution B/W', only the B/W of the 'Narrow band FM' of 12.5 kHz and 'Wide FM' of 180 kHz.
I notice some SAs' give a 10 kHz option. Is that overkill? I found this in the owners manual;
Quote:


The scan will start from the left side of the LCD at a rate of 80mS/CH or 12.5Ch/Sec. This is 3.2sec/Div. In the 80Bar graph display the scan speed is 6.4Channels per second or 1.6 sec per division.

This is the 'old' spec as all new units (either model) are 125 ch/sec up from the 12.5 ch/sec of the older 3201 (all 3290s' are 125 ch/sec). That would change that quoated spec to 8mS/ch, correct?

Since you are familar with SAs', how important is the option of a tracking generator? Just where would that be used?
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post #16 of 27
5/28/06 at 7:25am
A tracking generator is used as a "transmitter", with the S-A as a "receiver", for tuning filters. The TG generates a swept frequency, and the SA stays in track with it. The TG also provides a controlled source impedence going in to the filter or other Device-under-Test (D-U-T, as the lab guys call it).
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post #17 of 27
5/28/06 at 9:45pm
Quote:
Originally Posted by videobruce View Post

I take it you mean 100 kHz

I still say, "cycles per second". And I still transport my test gear in my beach wagon.
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post #18 of 27
5/29/06 at 8:11am
Thread Starter 
Thanks Ken. Other than that, what other use would it be for?

"Beach wagon"??
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post #19 of 27
8/16/06 at 1:06pm
Thread Starter 
Update on the above choices. I have found what B&K sells from another importer for around $900 less. They gave me a price of $1030 delivered where the B&K (same unit mfg. by Atten) is around $1900:

http://www.madelltech.com/m1-7.html

I have eliminated the 'Protek' and Avcom models because of price and features.
Instead, the Instek GSP 827 would be the one of choice, but I'm back to the 'price' issue. At $3275 it is by far the best that I found in that price range;

http://www.instek.com/GSP-827.htm
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post #20 of 27
8/17/06 at 1:23pm
if you donot need the device for to long, have you though about renting the test device?
milt
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post #21 of 27
8/18/06 at 5:36am
Thread Starter 
It would be a long term investment. I only mentioned the 'trap' tuning as an example. If it was just one project I would just of rented one.

Cons of the three choices:
Madell/Atten 5010 (w/o tracking generator); Used models for $875. Only two RBW settings: 20 & 400 kHz. No video filters. Lesser known company name.
Instek 810; Video BW is fixed to the RBW settings which are based of which resolution BW you set the scope for. $800 more than the above.
Instek 827; cost being 2x over the above. Big plus: NO CRT , variable VBW settings and up to 2.7 GHz coverage.
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post #22 of 27
6/21/07 at 12:58pm
For something way less expensive, check out the Aaronia Spectran handheld Spectrum analyzers.
Aaronia Spectran
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post #23 of 27
6/22/07 at 5:51am
Thread Starter 
Thanks. Looks interesting but, is it sold in the US?

Anyway, I went with the Instek GSP-810. I wanted the 827, but at 2x the cost, I couldn't justify that additional cost.
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post #24 of 27
6/22/07 at 6:48am
Quote:
Originally Posted by videobruce View Post

Thanks. Looks interesting but, is it sold in the US?

Anyway, I went with the Instek GSP-810. I wanted the 827, but at 2x the cost, I couldn't justify that additional cost.

Only on eBay. The Instek only goes to 1GHz. We need to check 802.11(x) and CCTV wireless frequencies, which are 900MHz, 2.4GHz and 5.8GHz. The next cheapest spectrum analyzer that handles those frequencies is closer to $10k
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post #25 of 27
6/22/07 at 6:53am
Thread Starter 
Quote:
The Instek only goes to 1GHz

Yes, I know which is why I considered the 827 along with a LCD display instead of a CRT. I really didn't need above 1 GHz though that would of been nice.
Have you ever used a 'regular' SA and what are the limitations of this other than the very small display and probable crude resolution?

Really don't like e-bay............

Did a quick search, is this it (under another name)?;
http://www.kaltmancreationsllc.com/rfanalyzer.html
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post #26 of 27
6/22/07 at 7:02am
Quote:
Originally Posted by videobruce View Post

Yes, I know which is why I considered the 827 along with a LCD display instead of a CRT. I really didn't need above 1 GHz though that would of been nice.
Have you ever used a 'regular' SA and what are the limitations of this other than the very small display and probable crude resolution?

Really don't like e-bay............

No, I haven't. I've always wanted one and could've used one many times but could never justify the cost.

My current job includes installing wireless CCTV and also working with an IT department that has had interference problems with wireless LAN. They have relatively deep pockets (though not $10k deep).

I wish I could find another inexpensive solution.
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post #27 of 27
1/11/09 at 6:54am
Thread Starter 
Bringing up a older thread, but still relevent, but limited for it's SA ability. Tecktronix sold something called a "Signal Scout RFM151" starting 11 or so years ago for around $2,500. That line was sold to Tempo which has now dropped support for it completely. Not the best news, but these can still be found, namely on flea-bay

It is a combination SLM, Spectrum Analyzer (very limited) and field strength meter combined into one package. After a very rocky start (long story) and a steep learning curve I wound up getting two of these off of flea-bay of all places (in spite of my eariler comment). The 2nd one was under $250. Best purchases I made.

Back to my orginal quest, I wound up upgrading to a demo Aeroflex (IFR) 2399A SA for a decent price with some nice options. Much more than I was orginally looking for though, but worth it.
FWIW, there is a somewhat no-name Chineese analog SA that just came out w/ a tracking generator and a TCXO for $800 available if you don't mind getting it directly from Hong Kong, or you can get it stateside for $1350. The Atten AT6011.
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