I built the standard 100w. LDG auto tuner from a kit. and installed it
in a steel box. It works fine ... BUT there is no screening between the
on-the-same-board electronics and the RF components. Nor is there any
obvious way of adding such screening. To be fair, I have never heard
anything from the LDG CPU, maybe because the normal band noise level
here overpowers anything from the AT-11.
One other consequence of the lack of screening is that the AT-11 CPU is
apparently vulnerable to RF. If you try to push too much through it, it
gets rather understandably upset.
In the TT 253 auto atu, the CPU and associated electronics are very well
isolated physically from the RF section. I have never heard any.
signals that I could attribute to the TT atu. And it is not vulnerable
to RF at any power level I can throw at it. But it cost a great deal
more.
Now if there was a way of isolating the LDG electronics from the RF
section .... ???
John G3JAG
On Fri, 12 Jan 2001, David Drew wrote:
> I noticed the same problem and diagnosed the AT-11 as the culprit on 80 CW
> just as mentioned. The AT-11 has been sitting my shelf ever since. Now
> using TT-253 which is just great..
>
> Dave W7DPW
>
>
>
> At 08:22 PM 1/11/01 -0500, Scott Walker wrote:
>
> >I find it interesting that TT may be selling the LDG
> >autotuner, considering the problem I had using it in my
> >Omni VI station. I built one of them from a kit about
> >2 years ago. It went together very well and performed
> >as advertised. However, I noted an increase of QRN when
> >operating full QSK CW with it. I became very sensitive
> >to internally generated noise in my shack because of
> >this, and at first I did not realize it was the
> >autotuner. I simultaneously had a problem with the Omni
> >6 "hearing itself" when certain parts of the front-panel
> >display were active, and TT told me to add a bypass cap
> >on the low-level board to fix that. There was still
> >another source of noise, and when I switched back to my
> >old TT 4229 antenna tuner, that noise
> >disappeared. I called LDG, and with some discussion they
> >speculated that I was hearing the processor in the
> >autotuner between each CW character as the AT-11 sensed
> >the SWR on the feedline. This was most obvious on
> >80-meter CW, where I operate daily (NTS nets). The only
> >solution was to defeat the autotune function entirely
> >by lifting a diode lead (switching it to manual does not
> >override the SWR autosensing) making the processor sleep.
> >I decided this was too much trouble and have stayed with
> >my old tuner. I made TT aware of this problem. So my
> >point is, I might be the only guy who had this
> >problem. I will be interested to hear results as more TT
> >users try out this autotuner.
> >73.
> >**********************************************************************
> > Scott Walker
> > New Cumberland, Cumberland County, Pennsylvania USA
> > E-Mail: N3SW@worldnet.att.net
> > CW: -. ...-- ... .--
> >**********************************************************************
> >
> >
> >--
> >FAQ on WWW: http://www.contesting.com/FAQ/tentec
> >Submissions: tentec@contesting.com
> >Administrative requests: tentec-REQUEST@contesting.com
> >Problems: owner-tentec@contesting.com
>
>
> --
> FAQ on WWW: http://www.contesting.com/FAQ/tentec
> Submissions: tentec@contesting.com
> Administrative requests: tentec-REQUEST@contesting.com
> Problems: owner-tentec@contesting.com
--
----------------------------------
E-Mail: $m
To: <tentec@contesting.com>
Date: $d
Time: $t
This message was sent by KMAIL under Linux - SuSE 7.0
-----------------------------------------------------
--
FAQ on WWW: http://www.contesting.com/FAQ/tentec
Submissions: tentec@contesting.com
Administrative requests: tentec-REQUEST@contesting.com
Problems: owner-tentec@contesting.com
|