[TenTec] Tuning Amp on 17 meters

[Richards]

Greetings TT Mavens.

Background -

I rarely work 17 meters SSB with my Omni VII.  Today, I reworked my 10 
meter vertical ground plane antenna into a 17 meter ground plane which 
measures about 1.3:1 SWR at around 42-45 ohms both in the back yard  and 
inside the shack using a RigExpert AA-230 analyzer.

I also have a TenTec Centurion and a TenTec 238C  and/or a Palstar 
AT-auto matchbox in line, which I alternate using at my whim on other 
antennas.  I generally put them in bypass mode when working a resonant 
dipole or vertical.

For 17 meters, I set the Centurion to the 15m Band, and set the LOAD and 
TUNE controls according to the chart in the user manual, and then fine 
tune for most power out with the TUNE knob.

	Sidebar: This seems to be a very forgiving amp...
	I can set the LOAD wide to either side of the
	recommended LOAD setting and it has no apparent
	effect, while the TUNE control is quite response
	and it is easy to tune to highest power out with
	very little movement.  The Plate Meter almost
	never changes no matter what I do.  I have never
	heard it arc or make any odd noises... he said
	knocking on wood...

When I briefly transmit a CW tone barefoot on 17 m, the rig meter says 
it sees 1.2 SWR, but when I put the amp in line, and run exciter power 
(maybe only 2-30w) I get 2.1:1 SWR.  I have not tried it on higher 
power.   I am sorry I don't recall what it did into my dummy load, and I 
cannot test that again right now because a humongous thunder storm is 
rolling in off Lake Michigan and ...well... you understand my reticence 
to be operating while that is brewing in the neighborhood.

The Inevitable Questions -

*   So... why does this happen?
*   Is this a normal occurrence?
*   Does this have anything to do with working 17m
	opposed to another band?  The radio usually
	reports SWR close to the antenna's inherent
	measurements on the other main bands like 40m
	20m, 15m, and 10m.  I have not tested for this
	on 12m or 30m.)
*   Using the auto tuner does not change this dichotomy
	of SWR reports.  I did not think it would, but
	I tried it anyway.

So... any thoughts?

----------------------  K8JHR -------------------------