[1000mp] Tuner quirk

[NB1B]

Mark

The following applies to Bandpass filters, such as the ICE or the W3NQN- I
don't know why it wouldn't apply also to TVI filters.

A TVI filter is designed for a 52 ohm input/output- if you HAVE to use the
ATU to get a match and power out, you don't have a 52 ohm system.  Trying to
use the TVI filter in such as system will not get you the TVI suppression
that you want, and will probably lead to premature failure, even at a low
power level, of the TVI filter.  When the ATU won't tune on a specific band,
the impedance presented to the ATU on that band is of such a nature that is
outside the ability of the tuner to match, so it will never shut off.

If you need the TVI filter, run the rig with the ATU off.  If you have to
use the filter, revise your antenna/feedline system so that it present 52
ohms at the frequency of interest.

Good Luck.

Dennis NB1B
----- Original Message -----
From: "Mark Tetrault" <tetrault@mv.mv.com>
To: <1000mp@mailman.qth.net>
Sent: Monday, December 31, 2001 9:24 AM
Subject: [1000mp] Tuner quirk


> Anyone runinto this?
>
> My Mark V so far has been perfect. Yesterday I stuck a B&K TVI filter
> in line. Now the tuner doesn't want to tune 160, 80/75, and 10 meters.
> It tunes the other bands ok, but slower.
>
> I tried another filter, Bencher TVI, same results.
>
> I switched coax jumpers to the filter, same results.
>
> Pulled the filter and jumper back off line, tunes fine again!
>
> Does the MP/ MP Mark V not like TVI filters?
>
>
> mark
>
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