450KHZ IF Filter Alignment

Hi, I have realized that the Network-Analyzer is going into the so called narrow band mode when you set Span below 100Khz. For radio low frequency if filter alignment I have to set center frequency to 450Khz and Span to 50KHz to display the filter response in an adequate way. With this setting I get a sweep time of about 9 seconds. I wonder if there is a work around to improve the sweep speed to let me say 0,5 seconds to be able to perform an if filter alignment to a radio.

A second point using the scalar network analyzer is that delta marker is showing the db’s but not the delta frequency . Do I have to set it somewhere??

Thanks Peter

Hi Peter,

At 100kHz and below spans for the scalar network analyzer (SNA) sweeps, the device allows more time for the signal to settle, as many of our users are measuring narrow band devices with higher settling times. Setting the span above 100kHz (e.g. 105kHz), will prevent the devices from going into this narrow band mode. I do not think you will be able to get to a 0.5 second sweep, which is mostly a hardware design limitation in how fast the device can sweep and sync.

As for the delta marker not reporting delta frequency, this is a bug and not intended. We will get this resolved for the next release. Thank you very much for alerting us to this.

Regards,
A.J.

Peter,
Yes, for crystals and narrowband filters, we needed a separate mode with much longer settling time. We chose a specific span, 100 kHz, as the switchover point, assuming that people who want to look at the pass band of a device with less than 10 kHz bandwidth would do it with a narrow span. For wideband rejection, where maybe a parasitic capacitance dominates, the faster sweep mode should work fine.

Hi Justin and Andrew,
thanks for your fast answers. Yes I know for crystal testing and such a longer settling time is needed. For radios especially for vintage radios the last IF on 450-470 khz is of interest. With a filter-width of about 9khz at the 3db point a span of 50khz is perfect. I was able to get a very nice filter response with this settings but sweep time is an issue. With 105 Khz Span as Andrew suggested it might work but with a lack of clarity. Well in more modern radios we have also a crystal in the 450khz IF but specifically the vintage radio folks were asking for this feature after they have seen my video. Anyways it is a great device!

One little minor bug report I found in Spike:
Using black background and switching from normal SA sweep mode to harmonic viewer background and figures under the spectrum table are black, so you can’t read the values. Figures needs to switch to white to be readable.

Thanks Peter

Hi Peter,

Thanks for the bug reports. We will have these and others resolved for the next release. If your PC is on a network, the Spike software will alert you when a new version is available, expect a new version in the coming weeks.

Thanks again for your feedback. It was a lot of fun watching your review.

Regards,
A.J.

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