BBC channels frequency changes on Astra 2 due on 18/10/10

[Huevos]

Which is probably why they use individual twta's (travelling wave tube amplifiers)

I thought a TWTA was just a PA stage; a bit like an old radio valve.

 

[Analoguesat]

Well a satellite is basically little more than a bent pipe in space. You fire a signal up at it, the satellite collects it, does a bit of frequency shifting and amplification then pings it back down again

 

[Llew]

If there's any tuning to be done, it'll be in the frequency conversion stage, well before the TWTA. Possibly switchable oscillators rather than a variable one, which could drift.

An interesting subject, there's probably more detail to be found online somewhere.

 

[Llew]

TWTA design details -

_http://www.r-type.org/static/twta.htm

 

[Channel Hopper]

When I were a lad they were known as Travelling Wave Amplifying Tubes with the appropriate acronym.

Don't forget the original

“Either you are with us, or you are with the terrorists, or you are not any of those things.”
~ George W. Bush on the war against terror