[TenTec] T tuner (transmatch) losses?

[Robert & Linda McGraw K4TAX]

Most tuners have low loss when measuring input to output when matched to a
50 dummy load on the output.  When feeding a real load, one which has both
capacitive and inductive reactance's is when they show excessive losses.
One way to judge loss is by operating the tuner with near rated power into a
real antenna.  After about 2 minutes, turn off the power and carefully touch
each component.  Anything that is warm or hot got that way with RF heating.
Remember, RF that is used in the process of producing heat is not radiated
RF.

The ARRL did some tests a few years back. They had some 8 or 10 tuners, both
new designs and old ones.  Conclusion:  The old Johnson KW matchbox was the
best performer although it did not cover 160 meters.  I recall that the
Johnson 250 watt matchbox was also quite good but not as good as the KW
matchbox.  I seem to recall that the Tentec 238 was in the top performers in
terms of matching range and low loss.  I haven't looked but the evaluation
may be on their website.  Probably worth reading.

Here's one link:  http://www.arrl.org/members-only/prodrev/pdf/pr0302.pdf


73,
Bob, K4TAX

----- Original Message -----
From: "denton" <denton at oregontrail.net>
To: <tentec at contesting.com>
Sent: Monday, June 30, 2003 7:01 PM
Subject: [TenTec] T tuner (transmatch) losses?


> Hi all...anyone running a Murch UT-2000B? Have been following the TT users
> group and I compared the Murch to a Vectronics 1500....according to my
> wattmeter connected to a 50 ohm dummy load, I get at most 4 watts loss out
> of the Murch compared to the Vectronics....which indicated 20 watts loss
on
> 160!
> ----- Original Message -----
> From: "tongaloa" <tongaloa at alltel.net>
> To: <tentec at contesting.com>
> Sent: Monday, June 30, 2003 7:02 AM
> Subject: [TenTec] 2A GA Omni A, Omni D at w4rrw
>
>
> > Stayed til about 2AM, too old for all night. OmniA 20/80 OmniD 40/15
> > probably should have swapped though as no filters in D made it a bit
> > of a chore copying on crowded 40m CW. I can't imagine anyone
> > working FD without QSK. Swapped out homebrew KW T net
> > tuner for the MFJ on 40 and man what a difference. Must have been losing
> > half
> > the output power heating up the MFJ innards.
> >
> > -bob
> > ah7i/w4 op at w4rrw
> >
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>
>
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