On 2/2/2014 10:06 AM, Carl wrote:
Most tuners have insufficient C for efficiency on 160 and some even
for 80 and that includes the Dentrons.
For 160 a good 500pf is needed and 250-300 for 80.
The big Palstar tuners have worked well for me. The AT-5K and AT-5K HP.
I don't see the AT5K HP listed any more. It was a coax only tuner with
no metering which was ideal for me.
I've had no problems with the half sloper, center fed droopy dipole on
160, or the Fan Dipole on 75. The Dentrons and MFJ 989 series would all
"hiss" at me on 160 near the top end of the band at much over 1 KW out.
The AT5K series have 600Pf at 6 KV while the AT2K only has 400 Pf and
the AT4K has 460 Pf @ 6 KV
I don't know how their smaller units would do, but I expect/guess they
would have the same problems as the other tuners with those ratings as
they all get derated at low impedances OTOH they do have a higher
voltage rating.
73,
Roger (K8RI)
David, that HB tuner you sold me before moving down to the swamplands
would have been ideal.
Carl
KM1H
On 2/1/2014 3:31 PM, qrv@kd4e.com wrote:
The Clipperton L, when tweaked to run efficiently, is
supposed to get 1200w+ out from 160-10m.
Most tuners that cover the frequency range and the impedance ranges
should work well. Remember, that thy all are derated when looking
into a low impedance. So you need one that will operate at that
power into that impedance with a reasonable SWR. Of course the 160
and 75 meter antennas are likely to have lower impedances and small
frequency excursions bring with them, large swings in SWR.
A tuner is a tuner is a tuner. It's just that to save on costs quite
a few have limited power into low impedances as well as SWR limits.
Those three parameters, Impedance, power, and SWR limitations where
you wish to operate are paramount.
73
Roger (K8RI)
Anything other than a Dentron MT-2000 or MT-3000 built
right & use a tapped inductor?
I know I'd need to add some capacitance for 160 & 80m.
Thanks!
David
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