Can someone help me with my Rigol DSA815-TG setup?

[KC9KEP]

Hello all,

I'm trying to do something that I would think to be very simple.

For the sake of mastering this, I have connected my Heathkit battery powered RF generator
to my Rigol DSA815TG  (I used a 10 dB attenuator .. just in case.)

If I set my RF generator to 3.5 MHz, and turn on the AM modulation (1 KHz), I would expect to
see 3 lobes; a 3.5MHz lobe and a (3.5MHz + 1KHz) and (3.5MHz - 1KHz) lobe.

Of course, I set a fairly small span to see this.

I can see the center frequency and upper & lower "sidebands" but I cannot
get a nice stable display.  The 3 lobes bounce around.

I would think this would be easy to see .. like the transmitter graphics that are
published in the ARRL handbboks.

Can someone with more experience suggest what I should be doing
to set up analyzer?

Much thanks all!

--KC9KEP

[cmatten]

You'll probably find it is drift with the generator. I know if I connect my MFJ269 up to my DSA-815, the frequency drifts around.

[PA4TIM]

You are looking at the drift and imperfection of the heathkit. Use a generator that is locked in frequency. For instance coupled to an external timestandard, or with a TCXO, or pll ect not a feeerunning homenade kit. Perfect for many things but not testing a SA.

[PA0PBZ]

What they say. To see the lobes you will have to set the span to something like 500Hz-1KHz per division. That also means that if the heathkit drifts 1KHz your whole display will drift one or two divisions. You could try singe shot mode, I expect that the Rigol can do that. At least the display will not bounce around then.

[deephaven]

Try lowering the scan rate and attenuating the signal some more.

[gm0otb]

You will find that the lobes bounce around because they are being modulated with AM at 1khz, if you turn the tone generator off it should look stable (apart from transmitter drift)

[gm0otb]

Done a quick test for you, setup as follows:

Generator settings:
Main Carrier Frequency= 3.5mhz, with1khz AM tone, Shape=Sine, Depth=100%

DSA815 settings:
Centre Freq=3.5 Mhz, Span=6.250Khz, 10db Attenuator internal on, 10db external Attenuator in-line, Scale Typle= Log or Lin for a clearer view. RBW=100hz, VBW=100hz

Try that, that should give you what you want to see. main cariier with side bands

Hope this helps Ray.