Ahhh, the fun of MATV setups gone bad! [Linked Image]

Albiet, nowadays (since 2001 to be exact), equipment is easier for end users to obtain, install and configure (plus plan out!) - resulting in a record low in panic calls to "come fix it!!!"
Haven't dealt with any calls for almost 2 years!

Now prior to that (<2001), things were much different, and had many odd mismatches and incorrect connections to deal with.

Problems ranged from the very simple, to the very extreme, as:

  • Incorrectly setting TV/VCR to a "Dead" VHF channel - typically Ch 03 (60-66 MHz),
  • Inputs/Outputs swapped,
  • RCA type patchcords for line level patching either in bad shape, or patched thru incorrectly,
  • No AC power to preamps, dist. amps or MUX(es),
  • Really crappy make-up on "F" connectors, loose and / or incomplete connections,
  • Using RG-59u Ethernet type coax (10 base 2) with RG-6 coax and connectors, or RG59 connectors on RG-6 cable,
  • Using Ethernet 10 base 2 coax - with / instead of - RG-6 cable,
  • Connecting any type of 75 ohm Z coaxial cable directly to 300 ohm Z terminals, without going thru a Z matching transformer,
  • Long unamplified looped runs, using a bunch of 3-way splitters,
  • Driving VCR output, or CATV input, directly into a VHF/UHF Antenna,
  • Poor connections thru RF switching items - such as Video Game Interfaces,
  • Broken RF in/out connections on TV or VCR,
  • VHF / UHF Antenna setup and aiming problems,
  • DBS Antenna setup and aiming problems,
  • Kinked feeders (causing standing waves),
  • Being stepped on by other broadcasted stuff (herringbone effects from HAM setups, etc.).


Ran into all sorts of issues with VHF / UHF Antenna setups.

The typical Antenna for multiband TV here is the Parasitic Yagi.

The larger VHF section consists of a Log-Periodic Dipole array, which the driven element is located near the UHF section at the front, and the reflecting elements can be "swept forward" (angled to 60°) to increase gain of lower VHF band, or not swept (straight / 90°) for normal overall gain.

The UHF section is typically a multi element Dipole arrangement - sometimes using a "Bow Tie" - and normally surrounded by a corner reflector array (reflectors above and below are 45° + and -).

Antenna problems include Off-alignment, 180° alignment (facing backwards), ½ the elements swept back, swept elements laying on unswept ones, damaged, missing or broken rear reflecting elements, other elements missing or damaged, reversed UHF reflectors (seriously!), damaged, missing or "tweeked on" driven elements and/or connections to it,
no Z matching transformer (mentioned before), bad mounting location or height, and use of 300 ohm Z lead in wire which is in bad condition, plus is strapped directly to Antenna mast, other cables, metal pipes, etc. (run without stand-offs).

Some of the location problems result in "Ghost" reflections from trees and buildings.

Some "Fringe Areas" have low power problems, which usually result in channels being stepped on, or just turn out to have a solid "Ant Race" over a snowy picture.

The Hz's here cover:

<OL TYPE=1>

[*]Lower VHF TV Bands (Ch. 02 thru 06): 54 MHz thru 88 MHz,

[*]VHF FM commercial Radio: 88 MHz thru 108 MHz,

[*]Upper VHF TV Bands (Ch. 07 thru 13): 176 MHz thru 216 MHz,

[*]UHF TV Bands (Ch. 14 thru 83): 470 MHz thru 890 MHz.
</OL>
TV channel occupies 6 MHz, whereas the FM Radio channel occupies 200 KHz.

Just some FYI [Linked Image]

Scott35

p.s. Thanks, Paul, for the thread!

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!