Thanks, I have found your web site informative and straight forward.
During my time operating a small electrical contracting business, I had experience installing high end AV systems for a Danish Company named Bang & Olufsen. I learned that nothing annoyed a customer more than outlaying large sums of hard earned cash only to have indifferent or poor television reception. I spent many hours spent tracing reception faults, and found that a few simple faults were often the cause of reception problems.

Cheap manufactured RF cables were so often a case of faults that I refused to use them and would insist on making up my own. Such faults would cause lines on channels broadcast at particular frequency ranges, as you describe.

VCR’s in the RF path would cause interference if the RF output channel of the VCR was close enough to broadcast channels, we learned to reprogram the VCR output frequency well away from broadcast channels. This fault is referred to as intermodulation.

Faulty AC power supplies in devices connected to the same power circuits ( in those days fax machines seemed to be troublesome) could generate RF interference at broadcast frequencies.

As you have alluded, the humble VCR is a product that has had it’s day, however I would be surprised if any of today’s AV products prove to be as enduring as it has.

Regards Phillip Armstrong
New Zealand