[BC] Tube transmitters do better in lightning

[Harveyesmith@aol.com]

Re "head examination" for keeping tube type transmitters in service past
their prime...


I sort of agree with you, but there are exceptions.  I experienced one...

A brand new Harris SX-1 on lightning hill in Limon, Colorado.

Over the 1st 5 years of service, the total cost of keeping that box on line
after lightning hits was over $40,000 parts and labor.

much of this was paid for by insurance, and yes, they wanted to replace
entire cards with new Harris design, no local repair, -keep the scrap 
cards locally
for future use- but the ownership was still miffed by the lightning caused
losses of air time and revenue

the SX-1 transmitter (running at the allocated 250 W daytime) was replaced
with a Gates BC-250 tube type running 810's (industrial heating and diathermy
still MFG. tubes)

Which then ran successfully without out further lightning outages for 4
years, till the station went dark.

Lets' face the obvious.... (the same truth that exists for continental
electronics in their 1 MW medium wave and short wave transmitters) 
also holds for am
stations worldwide... tubes can take lightning, transistors cannot.

Yes, continental still makes vacuum tube high power transmitters for the
obvious reason   -lightning survival-  they will tell you this at the NAB and
proudly so.


And guess what is saving the HDTV industry...  the one tube solution for 55
kW output (the klystrode) with an estimated 40k hours of service per tube...
it seems there is no fighting success and proven durability.

Sort of like the automotive industry trying to convert to plastic piston
engines, just does not seem to be working.

73's

Harvey E. Smith
2020 Baculite Mesa Road
Pueblo, CO., 81001-2456