On Thu, 30 Oct 2003 18:22:36 +0100, Sander deWaal
wrote:

BTW, I'm curious as to how the video sync pulses came into the
amplifier circuit.
Was it just strong radiation of harmonics and detection by the
amplifier, or was it pure superimposition on the supply lines?

Hey Sander, nice to see you back! How have you been?

--
The Devil

The Stainless Steel Boob Orchestra said:

Hey Sander, nice to see you back! How have you been?

Well, a lot has happened, but I'm doing much better than 2 years ago.
A story too long to tell here, but feel free to drop me a personal
note, the e-mail return address is valid.

--
Sander deWaal
Vacuum Audio Consultancy

Sander deWaal wrote in message

BTW, I'm curious as to how the video sync pulses came into the
amplifier circuit.
Was it just strong radiation of harmonics and detection by the
amplifier, or was it pure superimposition on the supply lines?

The RFI came in the phono input. The turntable leads acted as an antenna.

"Robert Morein" wrote in message

Since the RF amplifier is not baseband, distortion in the signal does not
appear directly in the modulated signal.

Interference beats do appear on the video (on the TV screen). If one
takes a signal generator and inserts an interfering signal (sinewave)
on an RF line, it will cause wavey lines to appear on video.

The the threshold of visibility is -60 dB. In audio terms, that would
be 0.01% distortion. The threshold of interference visibility for
video, seems to be about the same as the threshold of distortion
audibility for audio.


Even with simple class AB designs,
very high power output can be obtained with a small component count, since
the distortion products are broadband and not concentrated around the
carrier. By contrast, since the audio amplifier is a baseband instrument,
the distortion products are largely concentrated in the passband.


Audio amplifiers and CATV amplifiers are both broadband products. They
both face the same distortion challenges. A RF amplifier tested with
a signal of two sinewaves, say at 400 MHz and 500 MHz, will generate
exactly the same kind of second order and third order products as an
audio amplifier with a signal of 400 Hz and 500 Hz.

For example, the audio amplifier will generate sum and difference
distortion products of 100 Hz and 900 Hz. The RF amplifier will
gernerate sum and difference products of 100 MHz and 900 MHz. (And so
on, for all the other second and third order products.)

Bob Stanton

"Bob-Stanton" wrote in message
om

The threshold of visibility is -60 dB. In audio terms, that would
be 0.01% distortion.

-60 dB is 0.1%

The threshold of interference visibility for
video, seems to be about the same as the threshold of distortion
audibility for audio.

Yes, even under the most ideal conditions, audibility of nonlinear
distortion seems to go away someplace around or below 0.1%. Under non-ideal
conditions, several percent nonlinear distortion can be missed.

"Arny Krueger" wrote in message ...
"Bob-Stanton" wrote in message
om

The threshold of visibility is -60 dB. In audio terms, that would
be 0.01% distortion.

-60 dB is 0.1%


Yes, I agree. My mistake

-20 dB = 10% distortion
-40 dB = 1% distortion
-60 dB = 0.1% distortion

It just proves the old saying:
"There are three kinds of people in this world. Those who can do math
and those who can't." :-)

Bob Stanton

"Robert Morein" wrote in message
...

"Sockpuppet Yustabe" wrote in message
...

"Robert Morein" wrote in message
...



Snip



How big was that telescope Bob?