[TowerTalk] KT-34XA

[Maurizio Panicara]

Hi Dave,

Your methods are enough correct as much it is precise the used attenuator
pad and receiver S-meter reading doesn't drift.
To tell all the truth it's always good to terminate receiver into a 50 Ohm
and a resistive attenuator effectively does it.
Another point is to have enough distant location and tall supports, better
if the antenna under test radiates first lobe right to the other one as when
the latter is on a consistent higher tower (or an hill top) and at a proper
distance to be into the beam.
Concerning my KT34 and the many others I could check since 1986, the F/B is
also, and always, ranging into the 12-18 F/B range, whose number are way
down what I consider satisfactory for a multielements yagi.
Multiband shortened yagis are compromise and KT34 is not worse than many
other old styled tribanders that have better F/B but surely other gaps.
This consideration doesn't prohibit a new version can repair KT34 F/B
althought it's a difficult goal to obtain at no sacrifice when elements
spacing, one of 10 m director apart, is exactly the same for 10 15 and 20m.

73,
Mauri I4JMY

PS You can attract more S. Americans, and receive them better, with only
1/10 of your power into another antenna headed there.


----- Original Message -----
From: "Dave Hachadorian" <k6ll@juno.com>
To: <towertalk@contesting.com>
Sent: Tuesday, August 29, 2000 6:03 PM
Subject: Re: [TowerTalk] KT-34XA


>
>
>
> On Tue, 29 Aug 2000 14:57:00 +0200 "i4jmy@iol.it"<i4jmy@iol.it> writes:
> >
> > I prefer to have 2 antennas. One with good F/B and better S/N
> > heading
> > in a "main" direction and another one to check other headings and
> > elevations.
> > Old KT34s has good features but surely not F/B.
> > Who claims different didn't check with a spectrum analyzer but
> > eventually mesured using an S meter where the indication is not
> > logaritmic but linear (S0 to S7, typically) and divisions do not
> > correspond 6 dB x unit.
>
> Hi Maury,
>
> An easy way to measure F/B is as follows:
> 1. Have a local direct-path station transmit at a constant power level.
> 2. Point your antenna away from the transmitting station.
> 3. Note the s-meter reading.
> 4. Point your antenna at the transmitting station.
> 5. Insert attenuation in the receive line until the s-meter reaches
>    the first reading.
> 6. Read the F/B ratio off the attenuation setting.
>
> If a good attenuator is not available, I suppose it could be done
> with a wattmeter, by transmitting, and then reducing power until the
> distant station's s-meter matches, and then, noting the two power
> levels, use dB = 10 log P1/P2.
>
> I agree that even the best XA does not have state-of-the-art F/B,
> but mine, and W7WW's, both showed about 12 dB on 15 meters. From
> my location, it's rather nice to attract some South Americans and
> Carribbean while running JA's!
>
> Ciao.
>
> Dave Hachadorian, K6LL
> Big Bear, CA
> K6LL@juno.com



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