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Re: VLF: in VK?

To: [email protected]
Subject: Re: VLF: in VK?
From: Dimitrios Tsifakis <[email protected]>
Date: Sun, 10 Feb 2019 09:58:49 +1100
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> Not stellar SNR but the radiated power I reported originally (7.5 uW)
> is not correct. I think the capacitors have sustained some damage
> because they seem to introduce a series R of about 6 ohm! After I
> adjusted for that extra R, I now think that my radiated power was
> closer to 2.3 uW. No wonder they got hot, poor things!! So if I fix
> that problem I will gain another ~ 5dB for the same amplifier power.

Well, what do you know! The unexpected losses are not just the
capacitors (their contribution is probably small). It is also the
coaxial cable that I used between the antenna feedpoint and the
amplifier. One of the cables uses copper plated steel as the inner
core (which of course has a plating depth appropriate for the expected
skin effect at the _intended_ frequency of operation), the other has
copper plated aluminium (I think!). Even the jumper leads I used have
losses and it all adds up. I now appreciate the problem of using a
very low impedance antenna! Perhaps I should install another
transmission line from the inside of the house to the antenna but not
like the others, I should get the thickest speaker cable I can find
and use that :-)

73, Dimitris VK2COW

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