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Bandwidth rules Part 97.307 


Link to W9CF. Kevin analyzes key clicks mathematically.  

Related Pages:

An Intuitive Explanation of CW Bandwidth


What Causes Clicks


Occupied Bandwidth of CW


CW Bandwidth Analysis

I noticed W2VJN has proposed using absolute signal level at a fixed test spacing for click measurements. While I agree with George's suggestion (this link) we use an established test method, I strongly disagree that a 15Hz BW signal level measurement of the peaks accumulated in dozens or hundreds of scans is any more useful that listening off-frequency on a known good receiver.

While his mod is certainly better than a stock Yaesu, clicks also can be reduced more than his method provides without affecting ability to work weak signals. We don't need to watch output power and keep duty cycle to 50%, a slight adjustment of weight control would do the same thing. 

The real point is that both George and my suggestions are patches, they are not cures. Yaesu should step up to the plate and be responsible, and set an example for others to follow. 


We really need to establish a standard for measurement of transmitters on both SSB and CW, and it should be the effective spurious power level on close adjacent frequencies using typical CW bandwidth. Looking at one spot with slow sweep and peak storage on a spectrum analyzer is not a good test. 

It's pretty easy to see using the level (at one specific frequency) of a long-time average of signal peaks with a narrow filter sweeping by (which is what spectrum analyzers do) is a bad idea. 

Some radios have a sharp click on one edge, and nothing on the other. This causes peak energy to be higher in proportion to average energy. Radios can have higher peak level and actually do less damage to adjacent channels than a lower level click that hammers on both make and break, like the FT1000MK V does.

If I look on a peak sample and storage device like my spectrum analyzer, a radio could actually look worse yet bother adjacent CW bandwidth channels LESS than a radio that appears to be better.

A very narrow filter swept over the frequency with average storage of peaks does not account for attenuation slope modulation sidebands. I'd rather have a radio next to me with a steep drop in clicks at 500Hz than one with a single-pole gradually shaped slope even if the gradual sloped radio had less level. A peak comparison at some specified spacing misses too much.

SSB vs. CW

CW shares the same testing problems as FM and SSB. The FCC has changed some commercial voice tests to focus on spurious power level on adjacent channels, rather than using conventional but somewhat useless two-tone tests. A two-tone test shows the very best a radio is likely to do, not the typical performance. The FCC now requires normal modulation and an adjacent channel power level measurement in some cases.

CW and SSB testing for amateur use should be the same way.

I think is is shameful that manufacturers can't manage to spend a few hours of engineering time to select different component values, instead of sticking us with radios that have poor keying and IM characteristics. Frankly, there is NO excuse or justification for selecting wrong component values in a such a simple design area.

Is an excessively clicking radio legal?

Most of us agree right off the bat that some radios are annoying, and MOST people actually want to have the cleanest possible signal. Of course there are a few self-centered people who care less if they bother other people. They generally use the excuse that since a radio was sold it must be legal.

Here is a link that shows the exact 97.307 FCC text.

What do bad and good signals sound like?

For now, you can listen to some recordings and judge the difference.

Key clicks are off-frequency sidebands heard when there is no trace of a tone. If you listen carefully to these recordings, you will see the "hardness" of a properly filtered transmitter on frequency sounds very little different than the hardness of a wide, clicking signal.

Here are some sound files....these files are intended to be educational. While it isn't OUR fault the rigs were incorrectly designed, it is our legal obligation under 97.307 to correct the problems we have been stuck with. This is especially true when big antennas and amplifiers are used.

First, this is a mono recording of a virtually click-less radio. This station is 20dB-over-nine, and my noise is S2. When you listen, notice the "clicks" disappear right when any trace of tone vanishes. You'll notice the CW still sounds hard, and this station regularly broadcasts high-speed CW that hundreds of people copy.  This is the Click-free signal  of W1AW on 160 meters.

If you own a stock FT1000, FT1000D, FT1000MP or FT1000MP MKV (or any rig with a rise and fall faster than 4 or 5mS OR with any sharply rounded corners) you have work to do!

Notice key clicks can be heard long after the tone disappears totally, as we tune across the signal, yet there isn't any trace of receiver desense. S-9 plus 10dB station from England, 40-meters, using FT1000MP MKV tuning up 2 and down 2 using 500Hz RX filters. Significant clicks in the USA from England well after sunrise in England when signals are dropping. Imagine a 40 over MKV! This appears to be typical of all MK V's

S-9 +20dB in S-2 noise tuning from 1.5kHz below stock FT1000D (sorry, I snipped the above freq tuning to avoid call sign) This is typical of all FT1000(D)'s 

40-meter signal S-9 plus 15dB, background noise S-2, 500Hz filters, tuning up and down 2, recording of FT1000MK V. This rig cuts a 3kHz wide swath that is S-6 or stronger. 

40-meter signal S-9 plus 25dB, S-1.5 noise. Tuning up 2 and down 2, 500Hz filters in RX.  Omni-6 (This might or might not be typical of all Omni-6's. Ten-Tec reports an internal adjustment, when incorrectly set, causes these clicks. I've logged several Omni-6's with this problem, and some users continue to receive complaints after trying suggested mods. The characteristic I seem notice is key clicks extend downwards much more than upwards in frequency.) 

160-meter, S-9 plus 15 dB signal, S-1 noise, tuning up and down 2, Inrad-mod in FT1000MP

20-meter Kachina. S-1 noise, signal S9 plus 10. Which signal is the "real signal"? A snip of a clean signal answering him, about the same signal level, is at the end. Spurs went down 2.4 and up 2.4, and were spaced 600Hz apart. (This might not be typical of all Kachina's)

40-meter signal, S-9 plus 10dB signal S-2 noise, tuning up and down 2kHz, 500Hz filters, stock FT1000MP (this is typical of all stock FT1000MP's. If you own one that has not been correctly modified, you can be sure it has grossly excessive key clicks) 

160-meter signal, S-9 plus 20dB S-1 noise, tandem 250Hz filters in very high-dynamic range CW-only receiver, tuning up and down 1.2 kHz, stock IC765


2003 W8JI