Passband Analysis

Passband Analysis on my TS-850

Thanks to Gary E. Bold, ZL1AN, for his help and the original idea to do this!

These are passband plots of the response of my TS-850 to noise tuned in on an inactive frequency. I connected the output of my headphone jack through a matching transformer to the soundcard of my computer. I recorded the audio with various filter and control settings, then did a Fourier Transform on the sound file.

Don't pay attention to the absolute dB scale shown. The measurements are relative to oneanother only. You cannot conclude insertion losses, etcetera from this data. It's kind of for entertainment purposes only :)

If you would like to see how your rig compares. Then send me a recording! I can't promise a rapid turn around time, but I will get to it. Here is what you do:

Download the shareware sound recording program "GoldWave" from http://www.goldwave.com
Run GoldWave on your computing platform
Open a "New" file set for 10 seconds of 16 bit mono recording with either 8K or 16K sample rate (make sure you tell me which!)
Tune to an empty frequency and record the noise

Set the recording level correctly
Make sure the recordig level stays 'in the green'
Alternatively in the frequency display keep the baseline at a minimum and the passband peak at a maximum

Save the recording in MATLAB (.MAT) format
Zip up the recordings and send them to me with a description of each file

Bear in mind that this is an overall measurement. The effects of a speaker and microphone will be included if you do not record directly to the sound card. This is okay, but it will bias the plot to some extent. It is likely that the low frequency behavior shown in my plots is due to the action of the matching transformer I have inline between the rig and the computer.

I have a full compliment of four International Radio filters installed. The "first" IF (8.83MHz) has a choice of no filter, 6KHz stock, 2.7KHz stock, 2.1KHz InRad, or 400Hz InRad filter. The "second" IF (455KHz) has a choice of 12KHz stock, 6KHz stock, 2.1KHz InRad, or 400Hz InRad filter.

A plot comparing the overall response of just the CW filters. I include using the slope tune controls to modify the width to about 250Hz.

A plot comparing the overall response of slope tuning to modify the width to about 250Hz with both the cascaded 400Hz filters and the 2.1KHz filters. I include the unmodified 400Hz pair for comparison.

A plot comparing the overall response of just the SSB filters. I include a 'no filter' comparison with just the stock 6KHz filters cascaded.

An expanded version of the previous plot.

Use this plot to compare the filter skirts.

A plot showing the effectivness of the notch filter. The depth is pretty good, but the slope in not.

TS-850 versus Ten-Tec Omni-D

It's not a fair fight, but I am comparing anyway!

Comparisons between my current TS-850 and the Ten-Tec Omni-D I previously owned. The TS-850 is set for 500Hz pitch. The Omni-D is centered at 750Hz.

Comparisons between my current TS-850 and my previously owned Ten-Tec Omni-D.

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