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[CQ-Contest] Clicks (long)

Subject: [CQ-Contest] Clicks (long)
From: W8JI@contesting.com (Tom Rauch)
Date: Fri Mar 9 00:33:45 2001
 > But receivers ARE a problem. Many of the current crop of transceivers
 > with general coverage receive and other features are pretty sloppy in
 > the presence of many strong signals. Particularly if you look at the
 > mid-line transceivers used by the general ham populace (not just the
 > high-priced rigs used by serious contesters).

Sometimes receivers are the problem, but much more often it is
the transmitter. My FT-1000D was terrible for close spaced signals,
because Yaesu left the noise blanker's amplifier run full-tilt when
the NB was turned off.

I heard all kind of crap that wasn't "really there".

Rigs look good in ARRL tests because they use a wide test signal
spacing outside the roofing filter BW.

However, use of an attenuator will sort out these problems. At
some point you should clearly hear the problem go away. In the
stock FT1000, it was when I dropped the signals to about 20 over 9
or less.

 > Agreed. Let's eliminate the receiver possibility first. Then, if
 > there's still a problem, it must be in the transmitter.

Just use an attenuator pad, and watch the change. I hear plenty of
wide signals on receivers that overload at 10-20 mW of RF input!
That's about how strong I am at my own house, with receiving
antennas 1/2 mile away.

 > Thought question: could the ALC loop delay cause some of the clicks? I
 > know some Icom radios are notorious for keying up 100% power, then
 > popping down to a lessor level as the ALC takes action. This is
 > particularly true when trying to run QRP.

A 775DSP I had went to 350 watts on spike, and then back to
whatever I set the power at. So if I set the power at 80 watts, it
would bang the PA with 350 watts before settling back to 80. My
751A does not do that, nor does the FT1000D. My IC-706 goes to
150 watts before dropping back.

 > Given the number of amplifiers that can be driven to full output with
 > a mere 50 watts or so, could a 100 watt or more spike at the beginning
 > be a source of clicks, especially when QSK?

With QSK, it is more a relay timing problem. The overshoot might
give you a initial click, but it will be short lived because generally all
the ALC components remain charged even when on QSK.

It isn't an occasional click that causes the problem, it is the steady
stuff at every dot and dash.

Also remember the VCO settling problem when working split.

73, Tom W8JI

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