Doug I don't think it's at all unusual for a tuner of this design to be
derated during the tune up cycle. I use the LDG AT-11MP tuner with my Argo
V and the Ten-Tec 253 with my Omni V.9 and Herc II. Both tuners specify
tuning below a threshold. In the case of the 253 it specifies that 150
watts must not be exceeded during the auto tune cycle and the recommended
value is 50 watts. Keep in mind that this tuner is rated at 2 kW maximum RF
power.
As for tuning accurately at low power, here I'm afraid your also off the
mark. The LDG tuner I own requires 5 watts minimum to tune and it does a
fine job! I've checked it with my antenna analyzer.
In both cases I believe the reduction in drive during the tune cycle is, as
others have mentioned, to protect the "hot-switching" of the tuner relays
when a match is being sought. After the match is set and switching is no
longer a problem you can crank up the power.
I think you'll enjoy the tuner - the noise of all the relays switching gets
your attention, but LDG makes a nice box.
73,
Rick
VE7TK
Website: http://www3.telus.net/ve7tk
>Date: Fri, 15 Apr 2005 00:25:52 -0700 (PDT)
>From: Douglas <sparks06524@yahoo.com>
>Subject: [TenTec] LDG AT-100 Pro
>To: tentec@contesting.com
>Message-ID: <20050415072552.77747.qmail@web52801.mail.yahoo.com>
>Content-Type: text/plain; charset=us-ascii
>
>
>Anyone else using an LDG AT100 Pro tuner with their
>older Ten-Tec transceiver?
>
>I got the tuner for Christmas and can't say that I'm
>happy with it.
>
>After going into "sleep" mode, it would intermittently
>refuse to wake up.
>Last weekend I probably blew it out either by running
>80 watts into it from my old Swan 250C 6 mtr rig or
>else while using it with my Ten-Tec Corsair II.
>It will no longer tune anything over about 3:1 SWR
>on a HF band.
>
>After a careful and complete reading of the owner's
>manual, I discovered, in the "fine print" but not in
>the specifications page, that while the tuner is
>advertised as a 125 watt tuner in all LDG ads and on
>their website, when you read the fine print in their
>owner's manual, it states that power must be reduced
>to only 25 watts in tune mode when using a transceiver
>that doesn't have power foldback into high swr's.
>That's only 20% of the advertised power rating.
>
>I called LDG's customer service and sort of got a run
>around about their lack of truthfulness in
>advertising. I never would have gotten the tuner if I
>knew it was only rated for 25 watts in tune mode.
>As I said to their rep, "How can one even accurately
>measure 25 watts into an unknown antenna impedance?"
>With a Ten-Tec rig that depends on power supply
>current limiting rather than SWR foldback, one would
>have to be constantly reducing power to very low
>levels every time one changes frequency.
>
>I guess I'm used to shipboard tuners made by MacKay,
>Harris and others that are rated for rock solid tune
>capability at full rated power. I didn't expect the
>same quality for $220 bux but not an 80% derating....
>
>LDG is hedging about fixing it under warranty.
>Perhaps it doesn't matter since with a power rating
>capability of only 25 watts, it isn't too useful to
>me.
>
>I was a bit suspicious of its power rating when I
>opened it and noted that it was only using 600 v
>capacitors. That's certainly fine for 25 watts but not
>for 125 watts into a maximum load impedance of 1000
>ohms - per the specs. Peak-to-peak voltages, not
>including transients, could easily exceed 700 wolts
>under such conditions.
>
>I'm wondering if Ten-Tec broke their relationship with
>LDG over reliability issues?
>
>73,
>Doug/WA1TUT
>
>
>
>
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