Modern Electronics (was Re: List charter mods & headcount... ;

From: William Donzelli <aw288_at_osfn.org>
Date: Tue Jun 22 20:50:44 2004

> I don't work in the field (no pun ...) so I have no idea
> how soon it will be before new TV (and radio) transmitters
> are built using semis.

They have been building them for a while (minor correction to last light's
post - 200 kW solid state rigs are now available), and in the past five
years, they have actually made them quite reliable (now to the point
where they are basically fault tolerant). You can still buy some tube
based transmitters, but I doubt they will be on the market in five years.

> I just assume that the existing ones
> won't be replaced any time soon (since they presumably work)
> and that the natural replacement rate is relatively low.

Extremely low. The tube rigs being replaced will become the standby units,
and the current standby units (many dating to the 1950s) will go out to
pasture.

> Semiconductors have advantages in many areas (power, speed,
> robustness) but it may be that these do not apply (or do
> not apply so much) in the high power, high frequency arena.

The high power solid state designs use many, many smaller transistors
working in parallel. It took time for these to work properly, but now they
do. If pieces blow out, due to a lightning strike, they can be hotswapped
out, and I Love Lucy still goes out.
 
Minor correction: tubes rule over semiconductors in the robustness
arena. It is pretty amazing just how much abuse a tube can take and still
work (although perhaps in a weakened state).

William Donzelli
aw288_at_osfn.org
Received on Tue Jun 22 2004 - 20:50:44 BST