Topband: Topband Digest, Vol 217, Issue 17

[Rune Øye]

Hi Rick

Well I have not heard about it either but the info I got from the company
that makes the amplifier told me this.
There is no shunt static discharge at the moment. The antenna is 27.5 meter
vertical with a loading coil at the base of the antenna and it is DC
grounded.

73
Rune

ons. 13. jan. 2021 kl. 18:01 skrev <topband-request at contesting.com>:

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> Today's Topics:
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>    1. Re: Oscillation in Narrow band tuned antenna.
>       (Richard (Rick) Karlquist)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 13 Jan 2021 08:54:34 -0800
> From: "Richard (Rick) Karlquist" <richard at karlquist.com>
> To: Rune ?ye <rune.e.oye at gmail.com>, topband at contesting.com
> Subject: Re: Topband: Oscillation in Narrow band tuned antenna.
> Message-ID: <21b148b9-f744-b017-3260-a3c3cd7e47bc at karlquist.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> On 1/13/2021 3:13 AM, Rune ?ye wrote:
>
> > I have been told that Oscillation in Narrow tuned antennas can occur and
> > make damage to your equipment, radio or amplifier. It is really the first
> > time I have heard about this potential issue.  On 160m band, I use a
>
> Can you give us more details on this theory?  I've never heard
> of it.  Maybe it is something that only applies to modern LDMOS
> devices?
>
> > Reason for asking is that I have burned the final transistor in my radio
> > and the final FET`s in my PA is broken. It all happens ?out of the blue?.
>
> The first question I would ask is whether you have a shunt RF choke to
> provide a DC ground for the antenna.  If you do, verify that the
> connections to it are reliable.  I mounted a backup RF shunt in a
> little metal box with RF connectors that hangs off the output of
> my radio to make sure static never blows up the radio, no matter what
> antenna I connect it to.  This was after I left the radio connected
> to a dipole that didn't have DC short across it and blew up the first
> transistor in the receiver.
>
> > 73
> > Rune LA7THA
> > _________________
>
> 73
> Rick N6RK
>
>
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> End of Topband Digest, Vol 217, Issue 17
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