[TenTec] Centurion Squeal and Oscillation

[Robert & Linda McGraw K4TAX]

But all in all, the Centurion only has a maximum of 10 to 12 dB of gain. 
Really not a lot to become unstable in my mind.   Oh if one looses a 
parasitic suppressor then the gain at about 110 MHz goes quite high.  Thus 
serious trouble looms.  Band switches are very prone to arc and vaporize. 
Also I seem to recall that it was reported it continued to oscillate even 
after turning off the ORION with about 250 watts showing on the meter. 
Parasitic suppressors are a lot more critical and more complex than a few 
turns of wire over a resistor.  (Check out Rich Measures website for more 
dialogue on this topic.)

I've had mine for nearly 15 years.  Never had any instance where I observed 
any instability regardless of input or output conditions.   As to input Z on 
the amp, I see that it does vary quite widely and that's just the nature of 
fixed tuned inputs with GG amps.  It's a bandwidth vs. constant Z issue.  If 
the exciter is bothered by a 2:1 SWR then use an internal tuner or better 
yet one of the inexpensive 100 watt tuners.  Of course then one negates the 
broadband, no tune benefits.  In my case I don't see that the Omni is 
bothered by a 2:1 SWR while looking into the Centurion.

As to Tentec building things "as cheaply as possible", I say welcome to the 
world of manufacturing today.  Build it cheap, or more correctly stated, 
economically or go out of business.  Why do you think companies are moving 
out of the US?   I think the words here is "cheap" and maximize profits.   I 
can't imagine anyone going around looking for the most expensive thing to 
buy.  At least where I work they want the cheapest thing on the floor.  They 
look for what is described as the best value, which in some cases translates 
to cheap vs. economical.  A lot of folks don't know the difference between 
cheap and economical.

The manufacturing rule of thumb that I've always followed is a "factor of 
5".  That says if they put in a part that costs $1 then the retail price 
will increase by $5.  Increase the cost of the fan by $10 and the retail 
price goes up by $50.  Just how many $10 parts can be put in the box before 
the retail price is out of realistic market range?

And yes through my years of commercial electronics, I say "if it worked once 
then fix it, don't re-design it."

73
Bob, K4TAX