[Kenwood] TL-922A question

Thu Dec 8 22:23:20 EST 2011

At 11:57 AM 12/8/2011, rb wrote:
>Folks, you've done me a great service. Through your remarks, I've 
>gone back and looked at things through a fresh perspective.
>>The big lesson here is I trusted the relative power meter of my 
>tuner. I'll now use my TL-922A meters as my primary source of 
>what's going on.

A much better way to gauge the amount of power you're getting out of 
the amplifier versus the exciter is to tune everything up including 
the amp, then adjust the tuner so it reads fullscale on Forward. Then 
bypass the amp, and make certain the 101ZD is tuned up properly into 
the tuner, then read the scale WITHOUYT readjusting the Forward 
setting. While the scale is likely NOT linear, you should see it 
indicating around ten times less power than with the amp, ASSUMING 
the amp is actually being driven to 1500 watts INPUT power.
The reason I say to retune the 101ZD into the tuner is because the 
922's input SWR is very likely NOT as low as 1:1, and so the 101ZD 
has to be retuned at least slightly. Fortunately, however, it CAN be 
retuned for a different output impedance; solid state exciters 
cannot. And not all solid state exciters actually like a 50 ohm 
output impedance, either 8-/
Also, keep in mind that wattmeters measure ALL the power presented to 
their input... not just the fundamental, but also all harmonics. 
While your equipment SHOULD be emitting far too little harmonic 
energy to matter, you also have to remember that when so-called 
linear devices are overdriven to get every last watt of output power, 
the harmonics come up noticeably, sometimes drastically. This can 
also affect the antenna tuner, since it's power detection circuits 
also cannot discriminate between the fundamental and harmonics. This 
is often what is happening when, for example, you set up the tuner 
with low power and see 1:1 SWR, then plug an amplifier in line, and 
suddenly your SWR appears to be 1.5:1 or even 2:1.
SteveH, K0XP 
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