[CQ-Contest] Cheating - Big Amps

[Tom W8JI]

Not to get into the complaining fun, but some comments are not technically 
accurate and may mislead people trying to have a clean signal.

>From a purely technical standpoint:

> I ran Alpha 8100 at 1500w for 48 hours in RTTY mode for several years
> now without problems. Even Alpha users manual states that amplifier has
> to be driven at design power otherwise it will heat up, which we
> experienced when tried to operate at 750W.

Not true.

While dissipation doe not decrease linearly at the rate we expect with 
reduced power, it does not run hotter at less power. That is just a silly 
idea.

Typically **without retuning**:
2500w input/ 1500 w tube output / 1000 watts heat
1250w input/ 375 watts tube output / 875 watts heat

Other heat like tank heat or power supply is linear, half power = half heat 
except in the output device.

With retuning then half power  = half heat.

Tube heat does not go down as fast as we sometimes expect, but it always 
goes down. If it does not, then someone has a serious design problem or they 
do not understand their amplifier.

> Everybody with some amplifier building knowledge is familiar what
> happens when you run amplifier at 1500w designed with output filter for
> 5+ kW. It is not properly tuned and splatter is one of the products.

Not true.

First, the output filter has NOTHING to do with splatter. It only affects 
harmonics that are out of band.

Second, splatter is more often caused by people who turn a 100 watt radio up 
to 120 watts or more to make a marginal amplifier run more power or who do 
not know how to tune an amplifier.

Running a larger amplifier at lower power very rarely makes IM3 or high 
worse. Usually it is the opposite.

I know of many Hams who get inside FT1000's and other radios and turn things 
up to get a few dB more power. This is where the problems really are, and in 
people who do not know how to load an amplifier up properly.

Most of the equipment and amplifier damage here, and I am sure bad signals 
and damage everywhere, comes from people trying to squeeze that extra drop.

One of the stupidest most selfish things people do is to turn the power 
limit controls up inside radios. They are also usually the biggest 
complainers about other people.

73 Tom