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Re: LF: Re[2]: LF: RN3AUS 136 khz TX now!

To: [email protected]
Subject: Re: LF: Re[2]: LF: RN3AUS 136 khz TX now!
From: DK7FC <[email protected]>
Date: Fri, 13 Jul 2018 16:11:42 +0200
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Hello Jeff,

Am 13.07.2018 15:37, schrieb F6CWN:
Nice. The first time i saw a photo of F5WK. I know him from some years back but now he is not so much active on this reflector. He detected me many times on LF and VLF.

The difficulty of the kite is especially the takeoff in order to capture as soon as possible the good windy zone (not always easy in the middle of June!), But after that it goes ...
I do not speak also of the difficulties to pick up the wire when it falls with the kite in a field of corn! (You have to love the RADIO!)

I think i know exactly what you mean :-)

Now, I'm all alone to do LF (and no more young), so it goes slower ...

But you have enough time, right?

The main difficulty here (I am in Normandy, near the sea, where there is wind!) Is to find charitable souls able to share my tastes for "curious" things like the LF / VLF. It's long and you have to make concessions, but over time ... It's starting to become concrete!
Oh and when you are close to the sea, your ground losses will be very low too.

Just stay in contact here with the list. It is not only the antenna that must be tuned to resonance. It is also your mind and the mind of some people 'on the other side', the RX side! This must be tuned to a certain resonance as well, hoping for some Q :-)

I have several fields to grow antennas beverage, K9AY, and of course kite! But to this is added some difficulties such as energy and housing that are about to be resolved. Camping in the middle of winter is a bit hard for my old bones ...

On the power stage side, I'm thinking of a power MOS-based amplifier with IXYS IXFH94N30 at liquid-cooled IXYS (water + glycol), with the primary cooler out and the heat up (winter is good sometimes).

Is it a linear mode design? For a switch mode design you will not need such a heavy cooling. Looks fine for 2 kW +

The transformers are mounted on welder station ferrites (nominal frequency ~ 100 KHz, a good choice of manufacturers, thanks!) The "high voltage" power supply provided by two 51V 57 A server power supplies (HP EPS120) compatible with a capricious generator! (I think he's allergic to CW!)

Sounds solid.
I've done some CW on 8.97 kHz in 2011, using a weak generator that was able to produce 350W ('key-down') at that time. In CW the regulation has gone mad and the average power dropped. The PA was running at 320V DC (230V AC rectified, H-bridge using 4x IRFP460). But a parallel pack of 10x 6000 uF/350V solved the problem. For a short moment, like a 'dit' i got up to 1.8 A antenna current into my 300m vertical wire.

Good luck with the build up of your LF station and i'm looking forward to your big signal.

73, Stefan
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