Introduction

Ian Roberts, ZS6BTE wrote:

"As a matter of interest, were you able to get any video responses from band 3 MS?"

Yes, but only on relatively rare occasions for the following reasons:

- Meteor-scatter (MS) DX above 108 MHz is more difficult because refracted signal strength and duration drop sharply with increasing frequency.

- DX stations that are equipped for band 3 MS, typically use a 14 element 175-225 MHz yagi, 2dB noise figure Mosfet or GaAsFET pre-amplifier, low noise TV tuner with variable narrow IF bandwidth (D100, etc), and synthesised SSB VHF receiver with 2.4 KHz bandwidth (Icom R7000/7100/8500, etc). With this set-up, you can see weak pictures of high powered (>100 kW) band 3 TV signals via daily tropospheric scatter out to a radius of ~ 300 miles. Very weak (scanner level BFO) SSB video carriers can be received via tropospheric scatter on a daily basis up to ~ 500 miles. This level of sensitivity brings in several signals, hence there is the problem of finding a clear TV channel.

- Even though band 3 MS 'pings' can be heard using SSB every day, it takes a spectacular major meteor shower for faint fleeting pictures to be seen.

I initially heard about band 3 MS DX, after reading Roger Bunney's UK DX TV column. Since there is a large number of band 3 TV transmitters scattered through Europe, pictures were seen by UK DXers during every major shower. I remember Roger once received a 0249 Russian test card on band 3 via MS!

My first MS DX in 1982 was received on 175.25 MHz TVT6 Hobart, Tasmania (650 miles). On several mornings between 0600-0630, I saw flashes of the TVT6 PM5544 test card.

Highest frequency MS reception was SSB reception of 216.273 MHz ABRV11, Ballarat, Vic. Sporadic bursts of the ABRV11 vision carrier was heard daily at a distance of 480 miles.

450-900 miles seems to be the optimum distance range for band 3 DX via meteor scatter. So far, my most distant band 3 MS DX was 175.25 MHz, MVQ6 Mackay, QLD, at 900 miles. Other band 3 TV transmitters over 900 miles, for example, Townsville and Cairns, can't be heard due to local Sydney channels on 7, 9, and 10.

To enhance weak SSB video signals, I also use a tunable 16 Hz home-built narrow band audio filter connected to the R8500's audio line-out socket.



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Copyright 2009 Todd Emslie