Ridgeway Microwave Round Table

[g4hiz]

Hello everyone,

Joan (2E0HIZ) and I, attended the inaugural Ridgeway Microwave Round Table at Chilton Village Hall yesterday as did about 80 others. It was an excellent event with lots of familiar BATC faces and others interested in amateur TV as well as microwaves, with a couple of good talks, bits and pieces to buy (also freebies) and lots of 'show and tell'.

I took along a portable system to demonstrate reception of the QO-100 wide-band beacon on a smaller antenna and there were a number of people who were interested, so I thought that it may be useful to detail the demo. setup:

Antenna Offset parabola 71cm (across face) [believed to be a Triax TDS80]
LNB Octagon, LO 9750MHz, dual output (converted for locking but not used)
Receiver Minituner MkII
Display Portsdown 4, running built-in Longmynd Rx software

Antenna alignment used the Portsdown 4 Band Viewer with a SDRPlay RSPDx, initially capturing the QO100 narrow-band beacon, then switching to the large display 'MER meter' for fine pointing using the wide-band beacon. Using this method alignment took less than 5 minutes, although it is useful to have the elevation roughly set in advance. To receive both the narrow-band and wide-band transponders, you must have the capability to select the LNB volts for the correct downlink polarisation (eg 14V vertical for narrow-band/18V horizontal for wide-band).

With the 71cm antenna, the wideband beacon MER with no other carriers present was about 7.8dB (margin over threshold of about 3.1dB). Going to a 90cm should improve the MER further by a dB or more, depending on the dish.

If anyone is having difficulty with reception, I strongly suggest trying a different LNB type.

73
Jen G4HIZ

[Basil]

Nice set up, thanks for promoting DATV so well.

Seems an excellent sig strength from such a small dish.

[g4hiz]

As it happens, Chris, we captured your transmission also!
73
Jen

[G4IUG]

Hi Jen

The four of us were gobsmacked at the 1:1 demo you gave us !

Many Thanks Dave G4IUG

[Basil]

As it happens, Chris, we captured your transmission also!
73
Jen

Ha, old bird brain `0ILY ehh? Glad to be of service

[g8gtz]

Well done Jen - the demo definitely prompted sales in the BATC shop.

Noel