Problem with Shakespeare 5102 Centennial

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Eike Lantzsch, ZP6CGE - 16 Nov 2004 14:34 GMT

I have a problem with a Centennial Style 5102 antenna.
The antenna simply "does not get out".
The boat owner mounted the antenna to a short stainless steel mast
on top of his houseboat. The boat has a metal roof.
The output of his Icom M402 is 25W into a dumy load. The output to
the antenna is 14W measured with a DAIWA SWR-meter. There seems not
to be any reflected power (SWR 1:1). Where does the 25-14W=11W go?
A simple Lambda-quarter antenna easily makes contact over 40-50km
but this Shakespeare antenna does not even reach 3km.

Can this 6dB antenna have somthing internally broken - interrupted?
Transport damage?

If the connector would be bad I would see this immediately on the SWR.

Is the mounting wrong? Shakespeare states that the antenna does not
need a ground plane - this is my understanding of vertical half-wave
dipoles too - but can the mounting be too close to the metal roof?
Well, the 5102 seems to be a full wave antenna with phasing link.
But anyway my understanding is that this antenna has a voltage maximum
close to the metal roof at its base. This does not seem good to me.

I assume that Shakespeare antennas are well know, widely used
antennas with good reputation. But there are not very many down here
in South Amercia.

Any hint appreciated.
Kind regards, Eike

Reply to this Message

Chuck - 16 Nov 2004 15:46 GMT

Hello Eike,

Just curious. You used the DAIWA to measure the 25W into the dummy load
also?

Something is not right. The measured 14 watts could indicate a mismatch,
but that would surely show up as an SWR greater than 1:1.

Have you tested the DAIWA SWR function independently? Perhaps you have
two problems, rather than one? Is the DAIWA SWR meter calibrated for VHF?

Good luck!

Chuck

> I have a problem with a Centennial Style 5102 antenna.
> The antenna simply "does not get out".
[quoted text clipped - 24 lines]
> Any hint appreciated.
> Kind regards, Eike

Reply to this Message

Eike Lantzsch, ZP6CGE - 16 Nov 2004 17:57 GMT

Hi Chuck:
thank you for taking the time.

> Hello Eike,
>
> Just curious. You used the DAIWA to measure the 25W into the dummy load
> also?

No, it was measured with the power meter of a Motorola test set.

> Something is not right. The measured 14 watts could indicate a mismatch,
> but that would surely show up as an SWR greater than 1:1.
>
> Have you tested the DAIWA SWR function independently? Perhaps you have
> two problems, rather than one? Is the DAIWA SWR meter calibrated for VHF?

Makes me curious too because Shakespeare states an SWR of 1.5:1 and
the meter showed zilch reflected power. But the test with open and
shorted coax gave reasonable reflected power reading. But maybe the
DAIWA has a problem too. It alledgedly works for 140 to 525MHz.
Last time I used it, it gave me precise enough readings to
build a vertical lambda-half antenna with cavity resonator on
478.45MHz[*]. This antenna performs well up to over 50km with 20Watts
on a 30m tower and a walkie-talkie on the other side behind the
horizon. The HB9CV, which I built, reaches repeaters more than 120km
away with just 0.6W on 145MHz[**]. This is from the same location on
the same tower as the UHF antenna. So my knowledge of the accuracy
of the DAIWA SWR meter is only anecdotal.
If I only had a BIRD meter ...

Besides: The Shakespeare 8' antennas are rated as 6dB antennas.
6dB over what? Over a dipole or over a monopole?
That should either read dBd or dBi.

> Good luck!
>
> Chuck

Thank you.
Kind regards, Eike

[*] comercial license
[**] amateur radio license

Reply to this Message

Gary Schafer - 16 Nov 2004 17:25 GMT

Either the daiwa is lying to you or you have a bad connection between
the daiwa and the transmitter.

As Chuck said, did you check the daiwa with a dummy load?

Regards
Gary

>I have a problem with a Centennial Style 5102 antenna.
>The antenna simply "does not get out".
[quoted text clipped - 24 lines]
>Any hint appreciated.
>Kind regards, Eike

Reply to this Message

Boat Forum / Electronics / November 2004

Problem with Shakespeare 5102 Centennial