[TowerTalk] Castastrophic Consequences of Connector Failure?

[Jim Brown]

On Wed, 21 May 2008 11:16:24 -0400, Roger (K8RI) wrote:

>I wonder what the probability of expensive damage is if an antenna 
>connector, or adapter has a "hard" failure, i.e. an open or short 
>circuit/flashover, etc.  

It all depends on the luck of the draw with the particular 
amplifier you're running. I own three Ten Tec Titan 425 amps (the 
original). These are good amps, but the only protection is for hot 
switching of the T/R relay. Anything that causes the power supply 
to ARC can take out semiconductors, and can burn up traces in the 
power supply. If you can work on the amp yourself, you can fix it 
yourself in 4-16 hours (4 hours if you've seen it before, know what 
to look for, and have the parts in stock, 16 or more hours if you 
don't). If you have to send it to Ten Tec, it can be BLOODY 
EXPENSIVE -- they need both the RF deck and the power supply!

A serious mismatch of the load to the amp can cause excessive grid 
current in the final tubes, which is well known as a major failure 
mechanism in those tubes, (3CX800A7s). That can also be BLOODY 
EXPENSIVE. 

Putting it in dollars, saving $1 on a connector can easily cost you 
a lot of hours on the bench or $1,000 to someone else. Can you say 
"Pennywise and Pound Foolish?"

73,

Jim K9YC