[TenTec] Tuning Amp on 17 meters

[PC Anderson]

My understanding is that the auto tuner in the exciter should be OFF when driving the Amp. The input impedance changes with drive, so I've been told. Therefore, I allow the auto tuner to tune the antennas in bypass mode then ture off the auto tuner when driving the Amp.I may be all wet, but it works for me.Andy,,,W3LI
 > Date: Wed, 17 Apr 2013 15:52:20 -0400
> From: jrichards at k8jhr.com
> To: tentec at contesting.com
> Subject: [TenTec] Tuning Amp on 17 meters
> 
> 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 -------------------------
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