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Re: [TenTec] more oscilloscope questions

To: tentec@contesting.com
Subject: Re: [TenTec] more oscilloscope questions
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Reply-to: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Wed, 14 Jul 2010 13:31:23 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
I put down as many as I remembered that were less than 30 years old. 
Point is well made that this list is for discussion of all Tentecs, 
their care, and use and so that makes test equipment and antennas also 
fair game. I'm question driven, so I probably won't start discussions.

On 7/14/2010 6:16 AM, Paul Gates wrote:
> Jerry, K0CQ did not go far enough! I want see some discussion on Triton IV, 
> Delta, etc... Just kidding of course. Don't laugh b ut my primary rig is a 
> Delta 580 that is.
> Paul Gates
>> From: janed@burgoyne.com
>> To: geraldj@weather.net; tentec@contesting.com
>> Date: Tue, 13 Jul 2010 09:37:44 -0600
>> Subject: Re: [TenTec] more oscilloscope questions
>> Maybe Paul could start a thread for the solution for checking all those
>> things such as splatter, clean signal such as people that are blind. go for

The scope is the handiest tool for detecting splatter other than a 
spectrum analyzer which really only works well with 2 tone test signals 
for measuring because with two tones the frequencies of the intermod 
products are predictable while with voice they are more continuous 
across the band.

The first check with a scope is to drive the rig key down in CW to see 
the peak power as controlled by ALC. Make note of that, by setting the 
scope gain to fill between the first graticule line down from the top 
and the first garticule line up from the bottom of the display. Then go 
to voice and notice that going more than a few percent above that the 
rising spikes get cut off. That's what makes splatter, the envelope 
clipping from where the collector (or plate) voltage can't swing any 
more without going negative on the low side of the swing (or below the 
screen voltage on a tube where suddenly the plate current goes to zero 
and the screen current rises to replace the plate current to the 
detriment of the screen). The clipping point on SSB may be a little 
above the maximum CW carrier due to power supply dynamic regulation and 
some time delay in the ALC circuit. For those unable to see the 
oscilloscope, its not so much help, but listening with a well shielded 
second receiver tuned a few KHz off the transmitted signal (shielding 
needed to keep from overloading that receiver) will show up splatter or 
intermod products. Or sometimes listening to the transmitted signal the 
distortion of the PA clipping is detectable to the astute ear.

>> it. 73
>> Ed K7UC

73, Jerry, K0CQ
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