[Test-Equipment] RF spectrum analysis

Mon Jan 20 01:39:47 EST 2014

   If you are working on receivers the most important instrument you will need is a good stable accurate  signal generator with
with calibrated output level. Now, saying that, you need to take a look at your budget. If you have a couple hundred to spend you
can get a good digital one for a reasonable price. I say a good signal generator is necessary because you are going want to measure
your receiver's sensitivity and you will most likely want modulation capability. Fore some reasons 8640s go for way too much. Never
understood why. The 8656A is good and you can find them at reasonable price but you are always taking a chance of getting one with
problems with as-is sales. And if you don't have test equipment it is difficult to repair. Even some of them are getting to be over 30 years 
old.  If you want to go cheap an analog AN/URM25 is good, not real cheap but easy to maintain. Even if you have a good
digitally synthesized generator it would be helpful to have two so you can use one for a local oscillator perhaps while receiving the other.
  Then you need some kind of calibrated receiver or detector. a good start would be a AD8307 which is a surface mount part but not too small 
that you can dead bug construct on a ground plane. It cost about $12 at Mouser Electronics. 
  Since I am not in your shoes, I  can't really suggest exactly what you need but I can make some economic suggestions. 

73
Bill wa4lav

________________________________________
From: test-equipment-bounces at mailman.qth.net [test-equipment-bounces at mailman.qth.net] on behalf of james.liles at comcast.net [james.liles at comcast.net]
Sent: Sunday, January 19, 2014 11:03 PM
To: 'Discussion of Electronic Test Equipment'
Subject: Re: [Test-Equipment] RF spectrum analysis

Good evening Brian,

A sweep generator that has at least one marker, a 200 meg, two or four
channel scope, and signal generator will go a long way toward your goal.

An HP 3325A sweeper, a signal generator 8640B or 8656A, and a 200Mc or
better scope will be a great start and take you a long way without needing
re-education.  The 3325A will sweep from 1 cycle to 20Mc and provide a
marker(The marker is an imperative).  It is also rock solid.  The 8640B will
provide a great signal generator and with the 3325A providing an FM
modulation input to the 8640B you can sweep above 20Mc ---- if you really
need to.

Add a demodulator probe and you have a great and simple to use Sweep
combination.

If you have to go to a spectrum analyzer which is a superb addition you
really don't have to use a tracking generator.  Simply use max hold to paint
a complete picture.  An HP 8568B is a 100 cycle to 1.5Gig instrument.  It
can be used to design and service even audio circuits.  It's low end is 100
cycles.

I use the 8568B along with an HP 8447D preamp to non-disruptively profile
every stage in a radio.  Use it like a scope.  Wrap a shield around a tube
and measure even the lowliest signals without attaching a probe to a
circuit.  If I have to attach a probe use a series 2pf cap --- again, as non
disruptive as a FET probe.  You can also measure the passive amplification
in the front end of the radio or other circuits.  The uses are infinite.

The 8568B is the most expensive part of the equation at about $1200.00.

The 8640B maybe $350.00 ------- or 8656B &450.00

The 3325A $375.00

The scope $300.00 to $600.00

The scope.  I like Tektronix and there are several versions available.  I
prefer the analog variety and use the 2465B.  The 5000 and 7000 series
scopes are fairly inexpensive and use plug ins that range from a spectrum
analyzer, curve tracer, FET probe, back scratcher, and coffee cup holder.
Whatever you can think of they have a plug in for it.

These are simply my opinions and thoughts regarding the instruments that I
use on a consistent basis.  When thinking about a spectrum analyzer don't
forget audio.

Good luck Brian and a great day to you.

Kindest regards Jim K9AXN

-----Original Message-----
From: Brian Burns
Sent: Sunday, January 19, 2014 6:35 PM
To: 'Discussion of Electronic Test Equipment'
Subject: Re: [Test-Equipment] RF spectrum analysis

Hello Ron,

~ Maybe something like this will work for you
http://groups.yahoo.com/neo/groups/PHSNA/info
This is a current project and pretty simple to build, still evolving but
very functional right now.

That certainly looks like what I've had in mind. However my building
experience is from all the way back in the 1950's, and programming is way
over my pay grade! Do you mean I'm finally going to have to wrap my mind
around a "flow of holes"?

Cheers,

Brian

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